EPA-R4-73-028d
August 1973
Environmental  Monitoring Series

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                                          EPA-R4-73-028d
GUIDELINES  FOR  DEVELOPMENT
            OF  A  QUALITY
      ASSURANCE  PROGRAM
     Reference Method for  the Determination
      of Sulfur Dioxide  in the  Atmosphere
                      by

        Franklin Smith and A. Carl Nelson, Jr.

             Research Triangle Institute
     Research Triangle Park, North Carolina  27709
              Contract No. 68-02-0598

                RTI Project 43U-763


       EPA Project Officer:  Dr.  Joseph F. Walling

  Quality Assurance and Environmental Monitoring Laboratory
        National Environmental Research Center
     Research Triangle Park, North Carolina  27711
                  Prepared for

           OFFICE OF RESEARCH AND MONITORING
         U.S. ENVIRONMENTAL PROTECTION AGENCY
              WASHINGTON, D.C.  20460

                   August 1973

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This report has been reviewed by the Environmental Protection Agency and




approved for publication.  Approval does not signify that the contents




necessarily reflect the views and policies of the Agency, nor does




mention of trade names or commercial products constitute endorsement




or recommendation for use.
                                 11

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                       PREFACE

     Quality control  is an integral  part of any viable
environmental  monitoring activity.  The primary goals of
EPA's quality control program are to improve and document
the credibility of environmental  measurements.   To
achieve these goals, quality control is needed  in nearly
all segments of monitoring activities and should cover
personnel, methods selection, equipment, and data
handling procedures.  The quality control program will
consist of four major activities:
        •   Development and issuance of procedures
        •   Intra-laboratory quality control
        •   Inter-laboratory quality control
        •   Monitoring program evaluation and
           certification
All these activities are essential to a successful quality
control program and will be planned and carried out
simultaneously.
     Accordingly, this fourth manual of a series of five has
been prepared for the quality control of ambient air
measurements.   These guidelines for the quality control
                          m

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of sulfur dioxide measurements in the atmosphere have been

produced under the direction of the Quality Control Branch

of the Quality Assurance and Environmental Monitoring

Laboratory of NERC/RTP.  The purpose of this document is

to provide uniform guidance to all EPA monitoring activities

in the collection, analysis., interpretation, presentation,

and validation of quantitative data.  In accordance with

administrative directives to implement an agency-wide

quality control program, all EPA monitoring activities are

requested to use these guidelines to establish intralaboratory

quality assurance programs in the conduct of all ambient air

measurements for sulfur dioxide.  Your comments on the

utility of these guidelines, along with documented requests

for revision(s), are welcomed.

     All questions concerning the use of this manual  and

other matters related to quality control of air pollution

measurements should be directed to:
          Mr. Seymour Hochheiser, Chief
          Quality Control  Branch
          Quality Assurance and Environmental
            Monitoring Laboratory
          National Environmental Research Center
          Research Triangle Park, North Carolina 27711
                         IV

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     Information on the quality control of other

environmental media and categorical measurements can be

obtained by contacting the following person(s):

          Water

          Mr. Dwight Ballinger, Director
          Analytical Quality Control Laboratory
          National Environmental Research Center
          Cincinnati, Ohio 45268

          Pesticides

          Dr. Henry Enos, Chief
          Chemistry Branch
          Primate and Pesticide Effects Laboratory
          Environmental Protection Agency
          Perrine, Florida 33157

          Radiation

          Mr. Arthur Jarvis, Chief
          Office of Quality Assurance-Radiation
          National Environmental Research Center
          Las Vegas, Nevada 89114

     During the months ahead, a series of manuals will

be issued which describe guidelines to be followed during

the course of sampling, analysis, and data handling.  The

use of these prescribed guidelines will provide a uniform

approach in the various monitoring programs which allows

the evaluation of the validity of data produced.  The

implementation of a total and meaningful quality control
                             \
program cannot succeed without the full support of all

monitoring programs.  Your cooperation is appreciated.

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                           TABLE OF CONTENTS





Section




   I                         INTRODUCTION                               1




  II                       OPERATIONS MANUAL                            3



     -   GENERAL                                                         3



        PRESAMPLING PREPARATION                                         5



          Reagent Preparation (Step 1)                                  5



          Flow Rate Calibration (Step 2)                                7



          Absorber Preparation (Step 3)                                20



          Sample Identification (Step 4)                               21




          Package For Shipment (Step 5)                                21



        SAMPLE COLLECTION                                              23



          Sampling Apparatus Assembly (Step 6)                         23



          Operational Check of System (Step 7)                         32



          Sample Collection (Step 8)                                   34
                                              i


          Sampling Handling (Step 9)                                   35



        SAMPLE ANALYSIS                                                36



          Verify Documentation (Step 10)                               36



          Recalibrate the Critical Orifice (Step 11)                   36



          Reagent Preparation For Analysis (Step 12)                   37



          Develop a Calibration Curve (Step 13)                         41



          Colorimetric Analysis (Step 14)                              45




        DATA PROCESSING                                                46



          Perform Calculations (Step 15)                               46



          Document and Forward Data (Step 16)                          47





                                vii

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                       TABLE OF CONTENTS (Cont'd)


Section                                                               Page

        SPECIAL CHECKS FOR AUDITING                                    47

          Flow Rate/ Volume Check                                      48

          Measurement of Reference Samples                             50

          Data Processing Check                                        52

        SPECIAL CHECKS TO DETECT AND IDENTIFY TROUBLE                  52

          Average Temperature Environment of Sample
          Between Collection and Analysis                              53

          Measurement of pH of Final Solution                          54

          Interference Checks                                          54

          Volume of Absorbing Reagent                                  55

          Check of Sample Timer                                        55

        FACILITY AND APPARATUS REQUIREMENTS                            56

          Facility                                                     56

          Apparatus                                                    56


 III                      SUPERVISION MNUAL                           58

        GENERAL                                                        58

        ASSESSMENT OF DATA QUALITY                                     60

          Required Information                                         62

          Collection of Required Information                           62

          Treatment of Collected Information                           64

        SUGGESTED STANDARDS FOR JUDGING PERFORMANCE
        USING AUDIT DATA                                               66

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                      TABLE OF CONTENTS (Cont'd)


Section                                                               Page

        COLLECTION OF INFORMATION TO DETECT AND/OR IDENTIFY  TROUBLE     66

          Identification of Important Parameters                        66

          How to Monitor Important Parameters                          71

          Suggested Control Limits                                     71

        PROCEDURES FOR IMPROVING DATA QUALITY                      ,   74

        PROCEDURES FOR CHANGING THE AUDITING LEVEL TO GIVE THE
        DESIRED LEVEL OF CONFIDENCE IN THE REPORTED DATA               77

          Decision Rule - Accept the Lot  as Good  If No Defects
          Are Found (i.e., d = 0)                                      77

          Decision Rule - Accept the Lot  as Good  If No More
          Than One (1) Defect Is Found (i.e., d <_ 1)                    77

        MONITORING STRATEGIES AND COST                                 78

          Reference Method (AO)                                        78

          Modified Reference Method (AS)                                79

          Modified Reference Method Plus  Action A2
          (A7 = Al + A2 + A4)                                          79


  IV                       WNAGBENTIWJUAL                           81

        GENERAL                                                        81

        AUDITING SCHEMES                                               82

          Statistics of Various Auditing  Schemes                        83

          Selecting the Auditing Level                                 87

          Cost Relationships                                           90

          Cost Versus Audit Level                                      92

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                      TABLE OF CONTENTS (Concl'd)


Section                                                               Page

       DATA QUALITY ASSESSMENT                                         96

         Assessment of Individual Measurements                         96

         Overall Assessment of Data Quality                            99

       DATA QUALITY VERSUS COST OF IMPLEMENTING ACTIONS               103

       DATA PRESENTATION                                              107

       PERSONNEL REQUIREMENTS                                         108

         Training and Experience                                      108

       OPERATOR PROFICIENCY EVALUATION PROCEDURES                     109

       REFERENCES                                                     111

       APPENDIX - REFERENCE METHOD FOR THE DETERMINATION OF
                  SULFUR DIOXIDE IN THE ATMOSPHERE (Pararo-
                  saniline Method)                                    112

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                            LIST OF FIGURES


Figure No.                                                            Page

    1     Operational Flow Chart of the Measuring Process               4

    2     Schematic of Setup for Calibrating a Rotameter
          Against a Wet Test Meter                                     11

    3     Rotameter Calibration Data Sheet                             12

    4     Typical Rotameter Calibration Curve                          13

    5     Schematic of Setup for Calibrating a Critical
          Orifice Against a Wet Test Meter                             16

    6     An Absorber (24-Hr Sample) Filled and Assembled
          for Shipment                                                 22

    7     Sampling Apparatus Assembly                                  24

    8     Sampling Train With Sample Air Filter Installed              25

    9     Installation of Pinch Clamp on Vacuum Pump Inlet Line        26

   10     Close-up View of Absorber Installation                       28

   11     Removal of Dummy Absorber From Sampling Train                29

   12     Installation of Critical Orifice in the Sampling Train       30

   13     Connecting Critical Orifice to Exhaust Manifold              31

   14     Sample Record Sheet                                          33

   15     Flow Chart of Quality Control Checks in the
          Auditing Program                                             61

   16     Data Qualification Form                                      65

   17     Data Flow Diagram for Auditing Scheme                        84

   18A    Probability of d Defectives in the Sample If the
          Lot (N=100)  Contains D% Defectives                           85

   18B    Probability of d Defectives in the Sample If the
          Lot (N=50) Contains D% Defectives                            86

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                       LIST OF FIGURES (Concl'd)
Figure No.                                                            Page

   19A    Percentage of Good Measurements Vs. Sample Size
          for No Defectives and Indicated Confidence Level             88

   19B    Percentage of Good Measurements Vs. Sample Size
          for 1 Defective Observed and Indicated Confidence
          Level                                                        89

   20     Average Cost Vs.  Audit Level (Lot Size N-100)                 95

   21     Critical Values of Ratio s /o  Vs.  n                        100

   22     Added Cost ($)  Vs. MSE (%) for Alternative Strategies       105

   23     Sample QC Chart for Evaluating Operator Efficiency          110
                                   xii

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                            LIST OF TABLES


Table No.                                                             Page

     1    Apparatus Used in the Manual Pararosaniline Method            57

     2    Suggested Performance Standards                               67

     3    Methods of Monitoring Variables                               72

     4    Suggested Control Limits for Parameters and/or Variables      73

     5    Quality Control Procedures or Actions                         75

     6    P(d defectives)                                               83

     7    Required Auditing Levels n For Lot Size N=100
          Assuming Zero Defectives                                      87

     8    Costs Vs. Data Quality                                        90

     9A   Costs if 0 Defectives Are Observed and the Lot is
          Rejected                                                      91

     9B   Costs if 0 Defectives Are Observed and the Lot is
          Accepted                                                      91

    10    Costs in Dollars                                              92

    11    Overall Average Costs for One Acceptance-Rejection Scheme     93

    12    Critical Values of s /a                                       99

    13    Assumed Standard Deviations for Alternative Strategies       106

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                   ABSTRACT
Guidelines for the quality control of Federal reference
method for sulfur dioxide are presented.  These
include:

     1.  Good operating practices
     2.  Directions on how to assess data and qualify
         data
     3.  Direction on how to identify trouble and
         improve data quality
     4.  Directions to permit design of auditing
         activities
     5.  Procedures which can be used to select action
         options and relate them to costs.

The document is not a research report.  It is designed
for use by operating personnel.

This work was submitted in partial fulfillment of
Contract Durham 68-02-0598 by Research Triangle Institute
under the sponsorship of the Environmental Protection
Agency.  Work was completed as of July 1973.
                        XIV

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SECTION  I                     IliTRODUCTION


This document presents guidelines for implementing a quality assurance
program  for the manual (non-continuous) measurement of atmospheric sulfur
dioxide  by the pararcsaniline method.

The objectives of this quality assurance program for the pararosaniline
method of measuring atmospheric sulfur dioxide are to:

     (1)  provide routine indications for operating purposes
          of unsatisfactory performance of personnel and/or
          equipment,

     (2)  provide for prompt detection and correction of
          conditions which contribute to the collection of
          poor quality data, and

     (3)  collect and supply information necessary to describe
          the quality of the data.

To accomplish the above objectives, a quality assurance program must contain
the following components:

     (1)  routine training and/or evaluation of operators,

     (2)  routine monitoring of the variables and/or
          parameters which may have a significant effect on
          data quality,

     (3)  development of statements and evidence to qualify
          data and detect defects, and

     (4)  action strategies to increase the level of precision
          in the reported data and/or to detect -equipment
          defects or degradation and to correct same.
                                               '.»
Implementation of a quality assurance program will result in data that are
more uniform in terms of precision and accuracy.  It will enable each
monitoring network to continuously generate data that approach the highest
level of accuracy'attainable with the pararosaniline method.

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This document Is divided into four sections or chapters.  They are:

     Section I, Introduction - The introduction lists the overall
     objectives of a quality assurance program and delineates the
     program components necessary to accomplish the given objectives.

     Section II, Operations Manual - The Operations Manual sets forth
     recommended operating procedures, instructions for performing
     control checks designed to give an indication or warning that
     Invalid or poor quality data are being collected, and instruc-
     tions for performing certain special checks for auditing purposes.

     Section III, Supervision Manual - The Supervision Manual contains
     directions for 1) assessing sulfur dioxide data, 2) collecting
     information to detect and/or Identify trouble, 3) applying
     quality control procedures to improve data quality, and 4) varying
     the auditing or checking level to achieve a desired level of
     confidence in the validity of the outgoing data.  Also, monitoring
     strategies and costs as discussed in Section IV are summarized in
     this manual.

     Section IV. Management Manual - The Management Manual presents
     procedures designed to assist the manager in 1) detecting when
     data quality is inadequate, 2) assessing overall data quality,
     3) determining the extent of independent auditing to be per-
     formed, 4) relating costs of data quality assurance procedures
     to a measure of data quality, and 5) selecting from the options
     available the alternative(s) which will enable one to meet the
     data quality goals by the most cost-effective means.  Also,
     discussions on data presentation and personnel requirements are
     included in this manual.

The scope of this document has been purposely limited to that of a field
document.  Additional background information is contained in the final
report under this contract.

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 SECTION II                  OPERATIONS WNUAL
 GENERAL

 This  operations  manual  sets  forth  recommended  operating  procedures  for
 the colorimetric measurement of  sulfur  dioxide in  the  atmosphere using  the
 non-continuous pararosaniline method.   Quality control procedures and
 checks  designed  to  give an indication or warning that  invalid  or poor
 quality data are being  collected are written as part of  the  operating
 procedures  and are  to be performed by the  operator on  a  routine basis.
 In addition,  the performance of  special quality control  procedures  and/or
 checks  as prescribed by the  supervisor  may be  required of  the  operator
 on certain  occasions.

 The accuracy  and/or validity of  data obtained  from this  method depends
 upon  equipment performance and the proficiency with which  the  operator
 performs his  various tasks.   This  measurement  method from  reagent
 preparation through sample collection,  analysis, and data  reporting is  a
 complex operation.  Presenting detailed instructions covering  all alter-
 natives has not  been attempted in  this  document.   Rather,  general guide-
 lines are presented with special emphasis  on quality control checks and
 decision.rules applicable to known problem areas.   The operator should
 make  himself  familiar with the rules and regulations concerning the
 Reference Method as written  in the Federal Register, Vol.  36,  No. 84,
 Part  II, April 30,  1971 (reproduced as  the Appendix of this  document for
 convenience of reference).

 Instructions  throughout this document are  directed primarily toward a
 24-hour sampling period with comments on 30-minute and 1-hour  sampling
 periods when  appropriate.  Also, an auditing or checking level of 1 check
 out of  every  14  sampling periods or once a calendar month, whichever
 occurs  first, is used.   Sampling period durations  and  auditing levels are
 subject to  change by the supervisor and/or manager.  Such  changes would
 not alter the basic directions for performing  the  operation.   Also,
 certain control  limits  as given  in this manual represent best  estimates
 for use in  the beginning of  a quality assurance program  and  are, therefore,
 subject to  change as field data  are collected.

 It is assumed that  all  apparatus satisfies the reference method specifi-
 cations and that the manufacturer's recommendations will be  followed when
 using a particular  item of equipment (e.g.,  spectrophotometer  and wet
 test  meter).

 The sequence  of  operations to be performed during  each sampling period  is
 given in Figure  1.  Certain  operations  such  as reagent preparation  and
 flow-rate calibration (when  a rotameter is used as the flowmeter) are
 performed periodically.   The remaining  operations  are  performed during  each
 sampling period.  The operations are classified as presampling preparation,
 sample  collection,  sample analysis, and data processing.   Each operation or
 step  in the process is  identified  by a  block.   Quality checkpoints  in the
 measurement process, for which appropriate quality control limits are
•assigned, are represented by blocks enclosed by heavy  lines.   Other

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 PRE SAMPLING   PREPARATION

 1.  PREPARE OR OBTAIN OXIDANT-FREE DISTILLED WATER.
     PREPARE AND CHECK ABSORBING REAGENT.
 2.  CALIBRATE  FLOWMETER/FLOW CONTROLLER (ROTAHETER/CRITICAL ORIFICE'
     AGAINST A  STANDARD AS  SCHEDULED.
 3.  SELECT PROPER ABSORBER FOR SAMPLING PERIOD OF INTEREST.
     CLEAN AND ASSEMBLE THE ABSORBER.
 4.  RECORD IDENTIFYING INFORMATION IN THE OPERATIONAL DATA LOG BOOK
     AND ON THE ABSORBER TUBE.
 5.  PREPARE ABSORBER FOR DELIVERY/SHIPMENT TO
     THE SAMPLING SITE.


 SAMPLE   COLLECTION

 6.  ASSEMBLE SAMPLE COLLECTION SYSTEM IF NECESSARY
     INSTALL ABSORBER AND CRITICAL ORIFICE INTO THE
     SAMPLING TRAIN.
 7.  PERFORM SYSTEM OPERATIONAL CHECKS AND RECORD ON
     THE SAMPLE RECORD SHEET.
 8.  AMBIENT AIR IS SAMPLED AT A FIXED FLOW RATE FOR THE
     DURATION OF THE SAMPLING PERIOD.


 9.  REMOVE THE EXPOSED ABSORBER FROM  THE SAMPLING TRAIN,
     PREPARE THE SAMPLE FOR DELIVERY/SHIPMENT.
     OBSERVE AND RECORD ANY LOCAL CONDITIONS WHICH MIGHT
     AFFECT THE POLLUTION LEVEL.


 SAMPLE   ANALYSIS

10.  CHECK ALL DOCUMENTATION UP TO THIS POINT FOR
     ACCURACY AND COMPLETENESS.
11.  RECALIBRATE THE CRITICAL ORIFICE,  IF USED, AS IN  STEP 2.
     RECORD THE FINAL FLOW RATE IN THE  FLOW-RATE CALIBRATION
     LOG BOOK.
12.  PREPARE THE REAGENTS USED IN THE  ANALYSIS OF
     S02  SAMPLES.
13.  DEVELOP A CALIBRATION CURVE USING  EITHER THE
     SULFITE OR PERMEATION TUBE METHOD.
14.  MEASURE THE ABSORBANCE OF THE SAMPLE SOLUTION AT  548 nm.

DATA  PROCESSING

15.  PERFORM NECESSARY  CALCULATIONS TO  ARRIVE AT AN AVERAGE
     CONCENTRATION OF SO,  IN  M9/m3 AT  25°C AND 760 ra*g FOR
     THE SAMPLING PERIDOT
16.   RECORD CONCENTRATIONS AND IDENTIFYING DATA ON SAROAD FORM,
     ATTACH AUDIT DATA  AND FORWARD FOR ADDITIONAL INTERNAL
     REVIEW OR TO USER.
RECALIBRATE
 CRITICAL
  ORIFICE
                                                                              12
  REAGENT
PREPARATION
(ANALYSIS)
                                                                              13
  DEVELOP
CALIBRATION
   CURVE
                   FIGURE 1.  OPERATIONAL FLOW CHART OF THE ftAsupwG PROCESS

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checkpoints involve go/no-go checks and/or subjective judgments by the
operator with proper guidelines for decision-making spelled out in the
procedures.  T/teAe op&uitioni, and c/iecfei ate at4cuA4ed 4equen£uz££{/ 
one. ptogi.fc64fc4 ^tep by Atep through the. sequence o£ action* in F-tgate J.
The operator is responsible for maintaining certain records.  Specifically,
the following log books are maintained:

     (1)  Operational Data Log Book.  Sample identification data,
          completed gas sample record sheets, and analysis results
          are filed or recorded in the operational data log book.

     (2)  Flow-Rate Calibration Log Book.  Critical orifice or
          rotameter calibration data are recorded, dated and signed
          in this log book.

     (3)  SC>2 Calibration Log Book.  Completed calibration curves
          and control sample measurement data are maintained in the
          calibration log book.

PRESAMPLING PREPARATION

Operations included in this classification are (1) preparation of absorbing
reagent, flow-rate calibration, absorber preparation, sample identification,
and preparation of the absorber and flowmeter (critical orifice) for
shipment .

Reagent Preparation (Step 1)

In reagent preparation for sampling and analysis all chemicals should be
ACS analytical reagent grade or better.  Unless otherwise indicated,
references to water implies distilled water free from oxidants.  Only
Class A volumetric glassware should be used.  All weights should be made
on an analytical balance sensitive to the nearest 0.1 mg, or better.

Distilled Water - Water must be free from oxidants.  It should preferably
be double-distilled from all glass apparatus.  The purity of the water
should be checked when first purchased/prepared and before preparing a
batch of reagents for sampling or analysis.

Tei-t ^OfL pusUty - Distilled water can be tested for purity from oxidants
in the following manner.

     (1)  Add 0.20 mi of KMnO^ solution (0.316 g/£) to a mixture
          of 500 m£ of the distilled water and 1 m£ of H-SO, in a

          stoppered bottle of chemically resistant glass.

     (2)  If the permanganate .color (blue) does not disappear
          completely after standing for 1 hour at room temperature,
          consider the water suitable for use.

     (3)  If the permanganate does disappear, the water must be
          purified before using.
                                   5

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             pfioc.e.duAe. _ Water faliing tne purity test can be purified as
follows:

      (1)  Add one crystal each of potassium permanganate and
          barium hydroxide for each liter of distilled water.

      (2)  Redistill the water in an all-glass still.

      (3)  Perform the test for purity as described above.

      (4)  Repeat the purification procedure and  the  test for
          purity until the water checks pure-.

This distilled water, free of oxidants, is used  any  time water is required
in preparing reagents for sampling or analysis .

Sto/uige. 0& (LLt>tUULejd WOteA - Oxidant free water  should at all times be
protected from atmospheric contamination by storing  in container made of
material that has been proven to be resistant to solvation by, or reaction
with, the water.  Also, any tubing used during reagent preparation should
be of high resistant material.  Also, when removing  water from the storage
container the replacement air should be drawn through a vent guard (e.g.,
a drying tube filled with equal parts of 8-20-mesh soda lime, oxalic acid,
and 4-8-mesh calcium chloride, each compound being separated from the other
by a glass wool plug) .

Absorbing Reagent - Prepare a batch of absorbing reagent as directed in
Subsection 6.1.2 of the Appendix, page 113.  The preparation and subsequent
handling of the absorbing reagent should be carried  out under a ventilation
hood.
        pH c/iecfe - It is suggested that the pH of the absorbing reagent be
checked with a pH meter and a glass electrode standardized in a buffer
solution with a pH of about 4.5.  If the weighings and volumetric measure-
ments have been performed accurately and the chemicals and distilled water
are of the specified purity, the absorbing reagent will have a pH of approxi-
mately 4.0.  The reagent is acceptable for use if the pH is between 3 and 5.
However, -a significant deviation from a pH of 4.0 (e.g., pH < 3.5 or > 4.5)
although acceptable, would tend to indicate poor laboratory procedure or
impure chemicals and should serve as a warning to exercise more care in
preparing the next batch.  In the event that the pH is outside the 3 to 5
range, discard the reage'nt and check the chemicals and procedure before
preparing another batch.
                      cAecfe - As a check on the collection efficiency of
a new batch of absorbing reagent, it is suggested that dual samples be
collected and analyzed using two absorbers, one filled with absorbing
reagent from the old batch and the other filled with the new reagent.

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Compute the difference in the two measured concentrations by
                     d = (yg S0,/m3)  - (yg S0,/m3)
                               *•    n         L    o

where              d = the difference in yg SO-An ,
                 o
        (yg S00/m ) • = SO. concentration measured with new reagent,
              '    n     L
                 o
and     (yg S09/m )  = SO. concentration measured with old reagent.
              *    o     *
                                                  o            o
If d is less than or equal to [44 + .063 (yg S0?/m ) ] yg S0?/m , the new
                                                    o
reagent is accepted as no different than the old reagent (at the 3o level) .
If d is greater than the above value and there is no reason to suspect the
old absorbing reagent of having deteriorated, or an analysis error, the
new batch should be discarded and additional absorbing reagent prepared.

If a calibrated S0_ permeation tube is used for developing a calibration

curve (see Subsection 8.2.2 of the Appendix), the results include the
correction for collection efficiency and the above check need not be made.
                     /i&agent - Absorbing reagent can be stored in a
stoppered container.  It is normally stable for 6 months.  It should be
checked visually before each use and discarded if a precipitate has formed.

Flow Rate Calibration (Step 2)
                                               3                   3
Flow rates in the range of about 900 to 1100 cm /min, 450 to 550 cm /min,
              o
and 180-220 cm /min are used for 30-minute, 1-hour, and 24-hour sampling
periods, respectively.  It is recommended that rotameters or critical orifices
used for the 30-minute and 1-hour sampling periods be calibrated against a
wet test meter or a soap-bubble meter.  Flowmeters used for 24-hour sampling
should be calibrated against a soap-bubble meter for best results.

It should be noted that the above flow rate ranges are only approximate.
However, as long as these ranges are observed the flow rate will not be so
great as to (1) result in entrainment of the absorbing reagent, (2) cause
excessive evaporation of the absorbing reagent (e.g., more than 10 to 20 per-
cent of the total quantity), or (3) collect large quantities of S02 necessi-
tating the dilution of samples before analysis.  The lower limit will in
general result in a sample volume of air large enough to ensure the
collection of a quantity of SO- in the analytical range.

Rotameters should be removed from the system and cleaned every six months,
or after 30 days of operation, whichever occurs first.  It is recommended
that rotameters be calibrated after being cleaned, at any signs of erratic
behavior, or any time the flow rate measured by the rotameter differs by

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as much as 4 percent from the flow rate measured by a calibrated flowmeter.
Calibrated rotameter as used here refers to a rotameter that has been cali-
brated against a wet test meter or a soap-bubble meter.

Critical orifices are calibrated before and after each sampling period.

Rotameter Calibration - A rotameter is calibrated within an apparatus
similar to the field sampling collection device.  The absorber assembly
should conform to the same specifications as the field collection device,
and contain a volume of distilled water or absorbing reagent equal to the
volume of absorbing reagent used in the field device.

CaLUotuJL&Lon o^ a. fLotam&t&L agcuLn&t a. w&t tut mete/t - Figure 2 shows a
typical setup for calibrating a rotameter against a wet test meter.  The
calibration procedure is as follows:

     (1)  Set up the apparatus as shown in Figure 2 making the
          connections as short as possible and of the same inside
          diameter as is used in the field sampling train.

     (2)  Start the air flowing through the system and allow to
          flow for 5 to 10 minutes to allow the water in the wet
          test meter to reach saturation with the air.

     (3)  Before and after the complete calibration run, read and
          record room temperature and barometric pressure.  Record
          average values on the calibration form in Figure 3.  Use
          average values for subsequent calculations.

     (4)  Adjust the flow rate to about 20 percent of full scale
          for the rotameter with the needle valve.

     (5)  Take a pair of timed readings on the wet test meter (for
          best results use complete revolutions of the wet test
          meter), under steady flow,  for each of five or more
          uniformly spaced points on the rotameter scale, going
          from low values to high values.   Repeat, going from high
          to low.  Record rotameter reading, total flow, elapsed
          time of run, manometer reading at the wet test meter,
          manometer reading at the rotamter, and T  (temperature of
          the liquid in the wet test meter) for each run on the
          calibration sheet of Figure 3.

     (6)  Convert all temperature and pressure readings to absolute
          units.

                             °C + 273 = °K

                        in H20 x 1.87 = mmHg.

-------
 (7)  For each run correct the volume measured by the wet  test
     meter to the volume measured by the rotameter by
                      Vr " \T /\P / " m'
where   V  = volume of air passing through the rotameter  at
         r   T  and P ,
              r      r'

        T  = temperature of air entering rotameter (taken as
             the temperature of the liquid in the absorber),

        P  = barometric pressure minus the reading of  the
             manometer just upstream of the rotameter.

        V  = volume measured by the wet test meter,
         m
        P  = barometric pressure plus the reading of the
         m   manometer on the wet test meter,

and     T  = temperature of the liquid in the wet test meter.
(8)  For each V  calculate the corresponding flow rate by

     dividing the corrected volume,  V ,  by the elapsed time,
     t, in minutes for that run as
                           Qr = Vr/t .
(9)  For each run use a general form of the rotameter  equation  to
     calculate
                       " • (<>,") ftf2
where    I = rotameter reading (considered dimensionless here)
                                                 3
        Q  = flow rate from procedure 8 above  (cm /min),
        P.  = pressure at rotameter (barometric  pressure minus
             manometer reading)(mmHg),

        T  = temperature of air at rotameter  (°K), and

         K = determinable rotameter equation  constant with
             appropriate units to make  the  equation
             dimensionally consistent.
                               9

-------
     (10)  Plot on Cartesian Coordinates K.(y-axis) versus I (x-axis)
          for all runs.  Use regression analysis or by eye construct
          a best-fit curve to the data points.  The curve should
          approximate a straight line with zero slope.  Figure 4 is
          a hypothetical rotameter calibration curve.  Mark the values
          of T  and P  on the graph.

     (11)  Check all plotted points and rerun any that deviates more
          than + 5 percent from the best-fit curve for a fixed rota-
          meter indication.  Compute the percent deviation by


                                        K  -K
                    percent deviation = —-	 x 100
                                          K2


    where   K- = the K value of the plotted point, and

            K2 = the K value read from the best-fit curve for
                 the same rotameter reading as for KI.

     (13)  Forward calibration curve and data to supervisor for his
          approval.  File the approved data and curve in the cali-
          bration log book.

            a. /wtamvteA agcun&t a. 4oap-faubfa£e me^eA - Calibrating a
rotameter against a soap-bubble meter can be accomplished with the same type
apparatus setup as shown in Figure 2 with a soap-bubble meter replacing the
wet test meter.  The calibration procedure is as follows:

     (1)  Connect the apparatus as shown in Figure 2 with the soap-
          bubble meter replacing the wet test meter.  Use apparatus
          having the same specifications as the actual sampling
          train.

     (2)  Either immediately before or after the calibration,
          measure and record on the calibration form in Figure 3
          the ambient temperature and barometric pressure.

     (3)  Adjust the flow rate to about 20 percent of full scale
          for the rotameter with the needle valve.

     (4)  Take a pair of timed readings on the soap-bubble meter
          under steady flow, for each of five or more uniformly
          spaced points on the rotameter scale, going from low
          values to high values.  Repeat, going from high to low.
          Record rotameter reading, manometer reading at rotameter,
          total flow and elapsed time for each run on the
          calibration sheet of Figure 3.

          Note:  In Figure 3 the column for manometer for the wet
                 test meter reading is not used when calibrating
                 against a soap-bubble meter; also, T  becomes the
                 same as room temperature.
                                     10

-------
MANOMETER || IPI
 ROOM_
  AIR
                                                                                             TO
                                                                                           VACUUM
                                                                                            PUMP
                                              IM FINGER
                                                            TRAP
               Figure 2:   Schematic of Setup for Calibrating a Rotameter
                          Against a Wet Test Meter

-------
ROTAMETER SERIAL N0._
LOCATION
                   CALIBRATED WITH
AMBIENT/ROOM TEMPERATURE (Average)
ATMOSPHERIC PRESSURE (Average).
CALIBRATED BY
                 RELATIVE HUMIDITY_
                   DATE
Test
Point
1
2
3
4
5
6
7
8
9
10
Rotameter
Readi ng










Total
Flow










Elapsed
Time










Manometer Reading
Wet Test
Meter










Rotameter










» (W'Av
nOW'v»










Qr = Vr/t










K=(Qr/I)(Pr/Tr)1/2










                                 Figure 3:  Rotameter Calibration Data Sheet

-------
 FLOWMETER NO..
 LOCATION
u
UJ
      5
      4
       I
TEMPERATURE AT CALIBRATION (°K)
ATMOSPHERIC  PRESSURE AT CALIBRATION  (mmHg)_
CALIBRATED BY
             I
                       I
I
       0  0.2  0.4   0.6  0.8   1.0   1.2   1.4   1.6   1.8  2.0
            ROTAMETER  READING (ARBITRARY UNITS)
          Figure 4:  Hypothetical Rotameter Calibration Curve
                                 13

-------
 (5)  Convert all temperature and pressure readings to absolute
     units.

                          °C + 273 = °K

                    in H20 x 1.87 = mmHg.
 (6)  For each run, correct the flow rate measured by the soap-
     bubble meter to the flow rate measured by the rotameter by
where   Q  = flow rate through the rotameter at T  and P ,
               3                                 r      r
             cm /min.

        T  = temperature of air entering rotameter (taken
             as the temperature of the liquid in the absorber) ,
        P  = barometric pressure minus the reading of the
             manometer just upstream of the rotameter, mmHg,

        Q  = flow rate measured by the soap-bubble meter, cm /min,

        P  = barometric pressure, mmHg,

and     T  = room temperature, °K.
         m

(7)  For each run use a general form of the rotameter equation to
     calculate


                                     1/2
                      K- (Q/D l-
                            r
                                   r
where    I = rotameter reading (considered dimensionless here) ,
                                                 3
        Q  = flow rate from procedure 6 above (cm /min) ,



        P  = pressure at rotameter (mmHg) ,

        T  = temperature at rotameter (°K),

and      K = determinable rotameter equation constant with appropri-
             ate units to make the equation dimensionally consistent.
                              14

-------
     (8)  Plot on Cartesian coordinates K (y-axis) versus I (x-
          axis) for all runs.  Use regression analysis or by eye
          construct a best-fit curve to the data points.  The
          curve should approximate a straight line with zero slope.
          Figure A is a hypothetical rotameter calibration curve.

     (9)  Check all plotted points and rerun any that deviates more
          than + 5 percent from the best-fit curve for a fixed
          rotameter indication.  Compute the percent deviation by
                                        K  - K
                    percent deviation =	 x 100
                                           K2
          where   K. = the K value of the plotted point,

          and     K_ = the K value read from the best-fit curve
                       for the same rotameter reading as for K .


    (10)  Forward calibration curve and data to supervisor for his
          approval.  File the approved data and curve in the
          calibration log book.1

Calibration of Critical Orifice - A critical orifice is calibrated within
an apparatus similar to the sampling train used in the field.  That is, the
absorber assembly and tubing should conform to the same specifications as
the ones used when sampling.  It is recommended that either a soap-bubble
meter or a calibrated rotameter be used to calibrate critical orifices for
                                                     3
24-hour sampling where the flow rate is around 200 cm /min.  A wet test
meter, soap-bubble meter, or calibrated rotameter can be used for calibrating
the orifices for 30-minute and 1-hour sampling.

The calibration procedure is written in terms of a wet test meter with
special notes when the procedure would be different if a soap-bubble meter
or rotameter were used.  The procedure is ,as follows:

     (1)  Connect the apparatus as shown in Figure 5.

     (2)  Turn the vacuum pump ON and check the sampling train for
          leaks by slightly adjusting each connection while watching
          the manometer (the one next to the critical orifice) for
          any fluctuation in pressure.  Experience will indicate
          approximate pressure drops for the different sampling trains.
          Too small a pressure drop indicates leaks in the system and
          too high pressure drops indicates a restriction in the
          sample lines.

          Eliminate all leaks or restrictions before continuing.


                                   15

-------
                      THERMOMETER
MANOMETER
 ROOM_
  AIR
                                                                       ^
                                                                           MANOMETER
HYPODERMIC
  NEEDLE
                                                                           RUBBER
                                                                           SEPTUM
                                                                                           TO
                                                                                         -VACUUM
                                                                                           PUMP
                                                     TRAP
          Figure 5:  Schematic of  Setup for Calibrating a Critical Orifice
                    Against a Wet Test Meter

-------
(3)  To assure that the orifice is critical, read the vacuum
     gauge on the vacuum pump (see Figure 7; the vacuum gauge
     is mounted on top of the pump and connected to the pump's
     inlet port) and compare that reading to the pressure
     immediately upstream of the critical orifice.  This upstream
     pressure is obtained by subtracting the reading of the mano-
     meter directly upstream of the critical orifice from
     barometric pressure.  The orifice is critical if
                         P  > 0.55 P
                          v —       u


     where   P  = reading of vacuum gauge (mmHg),

     and     P  = barometric pressure minus manometer
                  reading (mmHg).

     See Reference 1 for a more detailed discussion of critical flow.

     For the 24-hour sampling train the upstream pressure is usually
     on the order of 735 mmHg (-29 in Hg) therefore, the vacuum
     gauge reading must be greater than 405 mmHg (> 16 in Hg) for the
     orifice to be critical.  Normal practice is to use a pump that
     will maintain a vacuum greater than 507 mmHg (20 in Hg).

     If sufficient vacuum- cannot be obtained, the system probably has
     leaks or the vacuum pump needs replacing.

(4)   Measure and record on the calibration record sheet; (1) ambient/
     room temperature,  (2) barometric pressure, and (3) relative
     humidity.

(5)   A.  Make at least  three timed runs when using a wet test meter.
         Time at least  one complete revolution of the wet test meter
         per run.

         Record the total flow (volume) measured by the wet test
         meter, elapsed time of run, and both manometer readings
         for each run.

     B.  If a soap-bubble meter is used, make at least three timed
         runs.  Record  the elapsed time, and the manometer (for the
         critical orifice) reading for each run.

     C.  When using a calibrated rotameter make three readings by
         shutting the pump OFF momentarily between readings.  Record
         the rotameter  reading and the manometer (for the critical
         orifice)  reading for each run.
                              17

-------
(6)   Correct  the indicated  volume/flow  rate  to  the  temperature
     and pressure at  the orifice  by:

     A.   For  a wet test  meter  use
         for  each of  the three  runs;

     where   V  = volume of  air passing  through  the  critical
              r                           3
                  orifice at T   and P  ,  cm ,

             T  = temperature of air entering  the  orifice  (taken
                  as  the temperature of  the liquid in  the  absor-
                  ber which  should be  room temperature), °K,

             P  = barometric pressure  minus the  reading of the
                  manometer  just upstream of the orifice,  mmHg,

             V  = volume of  air measured by the  wet  test meter, cm  ,
              m

             P  = barometric pressure  plus the reading of  the
                  manometer  on  the wet test meter,

     and     T  = temperature of the liquid in the wet test meter,  °K.


     Note:  Under this  setup the difference in V  and  V  should be
           fairly small since  T = T  and P   differs  f?om P  by
           about 25  mmHg or less.

     Compute  the critical volumetric flow rate of  the  orifice at T
     and P for each  of the  runs by
                          Qr - Vr/t
     where   t  =  the  elapsed  time of  the  run  in minutes.
     Compute the average,  Q ,  from the  three  runs  and  use  this value
     in subsequent  calculations.
                              18

-------
B.  When using a soap-bubble meter convert the measured
    volumetric flow-rate to the volumetric flow rate at
    the orifice for all three runs by
    where   Q  = flow rate as would be measured by the
                 soap-bubble meter at orifice conditions
                 of T  and P , cm^/min,
                     r      r
            T  = temperature of air upstream of the
                 orifice (taken as temperature of the
                 absorbing reagent which should be room
                 temperature, CK,

            P .= barometric pressure minus reading of the
                 manometer upstream from orifice, mmHg,

            Q  = flow rate measured by soap-bubble meter,
             m     3
                 cm /min,
                /
            P  = barometric pressure, mmHg,

    and     T  = room temperature, °K«
             m

    Note:  The difference in Q  and Q_ should be fairly small
                              r      TD
           when using the setup of Figure 5 since T  = T
                                                   r    m
           and P  differs from P  by approximately 25 mmHg.
                r               m

C.  When a rotameter is used as the standard, it should -itself
    be calibrated against a high grade soap-bubble meter as
    discussed in Step (2), starting on page 10.  Proceed as
    follows:

       (1)  Average the three rotameter readings to get I.
            From the calibration curve for the rotameter
            determine the value of K corresponding to a
            rotameter reading of I.

       (2)  Compute the measured flow rate by
                          19

-------
                 (3)  Convert the measured flow rate to the flow rate
                     at orifice conditions of T  and P  by
                                     pr yI/2
                                     K PrJ
                     where   Q  = flow rate at the orifice conditions
                              r                   3
                                  of T  and P , cm /min,

                             T  = temperature of air upstream of orifice
                                  (taken of absorbing reagent or room
                                  temperature), °K,

                             P  = barometric pressure minus reading of
                                  the manometer upstream of critical
                                  orifice, mmHg,

                             Q_ = flow rate measured by rotameter at
                                                          3
                                  conditions T  and P , cm /min,
                                              m      m

                             T  = ambient room temperature, °K,
                              m

                     and     P  = barometric pressure, mmHg.
                              m

     (7)  Once Q  has been determined by either of the above three methods,
          calculate


                             K = Qr/(Tr)1/2


     (8)  Record the K value and date of calibration in the calibration log
          book for that critical orifice.

A critical orifice should be discarded at any time its original K value
cannot be duplicated to within + 2 percent after having been cleaned.

Absorber Preparation (Step 3)

Selection of Absorbers - Select absorbers appropriate for the sampling
period to be used according to the specifications given in Section 5 of the
Appendix, page 113.

Cleaning Absorber Assembly - Before each use it is recommended that the
absorber assembly be cleaned by washing with hot water and placed in an acid
bath consisting of 1 part nitric acid, 2 parts hydrochloric acid, and 4 parts
distilled water for 1 hour.  Then rinse thoroughly with distilled water and
allow to dry.
                                    20

-------
Dispensing of TCM (Absorbing Solution) Into Absorbers - Transfer quantities
of TCM, appropriate for the sampling period to be used, as specified in
Section 7 of the Appendix into the absorber.

Note:  If the situation requires shipping apparatus from the central
       laboratory to the field site and vice versa, it is recommended
       that for 30-minute and 1-hour samples and all-glass midget
       impinger remain on site and the TCM be shipped in test tubes
       with screw-on caps using a teflon or equivalent inner liner on
       the caps.  The TCM would then be quantitatively transferred
       to the impinger by the field operator.

For 24-hour sampling the use of a set-volume reagent dispenser, such as a
50 mil repipet, for dispensing absorbing reagent into the absorbers is fast
and reduces the chance of a volume error.

Assemble the absorber as shown in the drawing of Figure 6.  Two tubing
caps are fitted on the tube ends to guard against contaminating the
absorbing reagent.  Shrinkable tape can be used around the tube and closure
to add mechanical stability and discourage tampering.  Alternatively, a
threaded absorber tube and screw-on cap could be used.  To guard against
accidentally forcing absorbing reagent out of the absorber, it is important
to always install the tube cap on the impinger tube first.  Color coding
the tube cap and tube would aid field personnel in identifying the cap and
act as a reminder to install that cap first.

On the first filling and after assembly, the absorber should be scribed or
otherwise permanently marked at the 50 mi level.  Glass impingers for
30-minute and 1-hour sampling come from the factory with a permanent scale.

Sample Identification (Step 4)

Each absorber should have the following identifying information semi-
permanently affixed by a stick-on label or marked directly on the absorber
with a felt-tipped pen:

     (1)  date absorber was prepared,

     (2)  sampling site number, and

     (3)  date to be used.

Obtain a calibrated critical orifice, if used in the system, and attach to
the absorber (see Step 5 below).  Record the absorber identifying infor-
mation, orifice number and date to be shipped in the laboratory log book.

Package for Shipment (Step 5)

In situations where shipping by mail is required, a container like or
equivalent to that used by EPA in the NASN program should be used. The
container is a block of wood with drilled holes of the proper sizes for
holding the absorbers and critical orifices.  This type container remains
serviceable for a long period of time.

                                    21

-------
Polypropylene
 2-Port  Tube
  Closure
      Glass
       Impinger
Polypropylene
  Tube
                                      Tube Cops
Heat  Shrink
  Tope
Etched  50 ml.
  Mark

Absorbing
 Reagent (TCM)
   Figure 6:  An Absorber (24-Hr  Sample)  Filled and Assembled
            For Shipaent
                         22

-------
SAMPLE COLLECTION

Sampling Apparatus Assembly (Step 6)

A typical sampling system consists of a collection unit, vacuum pump, and
a 7-day timer as shown in Figure 7.  The collection unit, in this case, is
a metal box which houses the sampling train.  .The sampling train is
maintained at a near constant temperature with a thermostatically controlled
heater.

Sampler Assembly - General guidelines are given for assembling a sampling
system used by EPA in the NASN program as shown in Figure 7.  Assemble as
follows:

     (1)  Attach "the membrane sample air filter unit to the glass
          inlet manifold.  The connecting tubing passes through a
          cutaway in the sampler box.  Support for the filter is
          provided by the tubing resting on the cutaway.  Care
          should be exercised when installing or changing the
          filter so as not to break the glass manifold.  Figure 8
          is a picture of a sampling train with the filter
          installed.

     (2)  Attach the sample inlet line consisting of polypropylene
          tubing and funnel to the sample air filter as shown in
          Figure 7.  Extend the funnel and sample inlet line out-
          of-doors through a window or other opening.  Support and
          secure the tube and funnel in position so that they will
          not come loose during sampling.  The funnel should be
          positioned to hang down so that rain will not be drawn
          into the sampler.

     (3)  Connect the metal exhaust manifold to the intake of the
          vacuum pump with tygon tubing.  Place a pinch clamp on
          this section of tubing as shown in Figure 9, but do not
          tighten.  Be sure all connections are airtight and that
          there are no constrictions in the tubing.

     (4)  Electrically connect the vacuum pump to the timer (see
          Figure 7) and the timer to a 24-hour 110 VAC outlet.  The
          sampler box is also connected to a 24-hour outlet.

Installation of Absorber and Critical Orifice - Correct installation of the
reagent-filled absorber and calibrated orifice is vital to the collection
of a valid sample.  Color-coding schemes for the absorbers and tubing are
frequently used to assist in locating absorbers in the right positions and
for making correct connections.  One such scheme is used in the following
procedure.  A close-up view of the absorber installation is given in
                                    23

-------
Figure 7:  Sampling Apparatus Assembly

-------
Figure 8:  Sampling Train With Sample Air Filter Installed
                             25

-------
Figure 9:  Installation of Pinch Clamp on Vacuum Pump Inlet Line

-------
Figure 10.  In this setup the top of the absorber around the impinger tube
and the tube cap on the Impinger tube are color-coded.  An accordian type
of tubing Is used to connect the glass intake manifold to the Impinger
tube.  Smooth tubing Is used for all other connections.

The Installation procedure Is as follows:

     (1)  Remove the dummy absorber (or used absorber) from the
          sampling train by gently but firmly pulling the Inlet
          and outlet tubing from the absorber as shown In
          Figure 11.

     (2)  Exchange the reagent-filled absorber for the dummy
          absorber.

     (3)  Transfer  the caps from the reagent-filled absorber to
          the dummy absorber.  Caution:  Always install  the tube
          cap or tubing on the impinger  tube  (color-coded side of
          absorber) first and remove them last, otherwise some of
          the absorbing reagent/sample may be forced  out the
          impinger  opening and be lost.

     (4)  Gently but firmly insert the accordian inlet tube (from
          the glass manifold) onto the color-coded tube  (impinger
          tube) of  the absorber lid.  Make certain the fit is
          airtight.

     (5)  Gently but firmly insert the smooth tubing  (from the
          trap) to  the unpainted outlet  tube of the absorber.

     (6)  Remove the critical orifice (calibrated hypodermic needle)
          from the shipping container.  Note:  It is  important that
          the needle be used and returned with the absorber that it
          was received with.

          For systems using a calibrated rotameter to measure flow-
          rate the rotameter remains in  the sampling  train until it
          is removed for cleaning and calibration.

     (7)  Insert the new needle into the center of the rubber stopper
          attached  to the membrane filter unit as shown  in.Figure 12.
          The needle must be put in straight.  If the needle is
          accidently bent during installation, it should be discarded
          and another absorber and needle used.

     (8)  Slide the base of the needle onto the metal exhaust manifold
          as shown in Figure 13.  Manipulate the needle  and/or rotate
          the trap, if necessary, to obtain a tight connection.
                                    27

-------
S3
oe


                                   Figure 10:  Close-up View of Absorber Installation

-------

Figure 11:  Removal of Dummy Absorber From Sampling Train
                            29

-------


Figure 12:  Installation of Critical Orifice in the Sampling Train

-------
Figure 13:  Connecting Critical Orifice to Exhaust Manifold

-------
      (9)  Recheck the arrangement, alignment, and tightness of all
          connections.  The following points should be verified:

          (a)  The accordian tubing from the glass manifold goes
               to the color-coded side of the absorber lid;

          (b)  the needle is not bent or obstructed;

          (c)  the needle forms a tight fit at the exhaust manifold;

          (d)  the inlet filter and tubing is tightly connected, and

          (e)  the vacuum pump connections are tight.

Note:  In situations where the sampling train is not housed in a closed box
the absorber must be shielded from sunlight during and after sampling.  One
means of accomplishing this is to wrap the absorber in aluminum foil.

Operational Check of System (Step 7)

      (1)  If a critical orifice is used in the system completely
          close the pinch clamp between the sampler and the
          vacuum pump (see Figure 9).

      (2)  Turn the timer switch to the ON position.  This should
          start the vacuum' pump.

      (3)  For systems using a critical orifice, record the vacuum
          gauge reading to the nearest whole number on the Sample
          Record Sheet of Figure 14, in the space marked "Start-Clamp."
          The gauge should read above 508 mmHg (20 in Hg) vacuum.  If
          it does not, make sure the pinch clamp is closed and the
          tubing is securely connected to the pump inlet.  If the
          vacuum reading remains below 508 mmHg (20 in Hg) the pump
          should be replaced.  Continue to (4) below.

          If a rotameter is used check and if necessary adjust the
          system flow rate to the prescribed value (e.g., 200 cm3/min
          (.2 £/min) for a 24-hour sample) and record the value on the
          Sample Record Sheet under "Remarks."  Continue with (5)
          below.

      (4)  Open the pinch clamp.  Record the vacuum gauge reading on the
          Sample Record Sheet in the space marked "Start-Open."  The
          gauge should read a little less than the reading with the
          clamp closed.  If it reads below 508 mmHg (20 in Hg), check
          for a loose connection at the pump.
                                    32

-------
       SAMPLER SERIAL NUMBER
       SITE IDENTIFICATION:  CITY OR TOWN
  SHIPPING PACKAGE NUMBER	



,  STATE	, SAMPLER LOCATION
WIND
DIRECTION
[ ] CALM
[ ] LIGHT
[ ] GUSTY
DATE

[ ] 0000 TO 2400
HOURS
[ ] OTHER EXPLAIN
VISIBILITY
[ ] CLEAR
[ ] HAZY
METER READING
START
END
OPEN


CLAMP


HUMIDITY
[ ] CLEAR
[ ] SCATTERED
[ ] OVERCAST
AVERAGE
TEMP (°C)

AVERAGE
PRESSURE (mmHq)

REMARKS & UNUSUAL CONDITIONS OR ACTIVITIES NEAR THE SITE

(jj
                                           Figure 14:  Sample Record Sheet

-------
     (5)  Record on the Sample Record Sheet the date that the sample
          was collected (one day only), and the time (if other than
          0000-2400 explain under "Remarks").

     (6)  Gently lift the sampling train halfway out of the sampler
          box (do not tilt the train) as in Figure 8.  Examine the
          absorber to make certain that it is bubbling.  If not,
          check for loose connections or a plugged line in the train
          and correct.

     (7)  Turn the timer OFF and set for sampling period.

Sample Collection (Step 8)

The sampling period is started and stopped by the timer.  The absorbing
reagent should be protected from direct sunlight during and after
sampling by covering the absorber with aluminum foil if it is to remain
outside the sampler or shipping block for any period of time.  At the end
of the sampling period, perform the following operations:

     (1)  With the timer switch ON, record the vacuum gauge reading
          on the Sample Record Sheet in the space marked "End-Open"
          if a critical orifice is being used and continue to (2)
          below.  For systems using a rotameter read and record the
          final flow rate, turn the timer switch to OFF, and continue
          with (4) below.

     (2)  Close the pinch clamp as tight as possible.  Record the
          vacuum gauge reading on the Sample Record Sheet in the
          space marked "End-Clamp."

     (3)  Turn the timer switch to the OFF position.  Open the
          pinch clamp.

     (4)  Check the condition of the membrane filter.  Replace if
          it is discolored or cracked.

     (5)  If the ambient temperature is below the thermostat setting
          in the sampling box,  check to see that the thermostat and
          heater are working.

     (6)  If possible, obtain an average temperature of the absorbing
          reagent for the sampling period.  For 30-minute and 1-hour
          sampling periods a temperature reading immediately before,
          after or any time during the period could be used as an
          average for the sampling period.
                                    34

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          For 24-hour sampling periods two approaches are discussed
          for arriving at an estimate of the average temperature.

          (a)  Place a minimum maximum thermometer in the thermostated
               box used to house the sampling train.  Report the
               average of the minimum and maximum temperatures for
               that sampling period.  The thermometer has to be reset
               before each sampling period.

          (b)  If a thermometer is not available for (a) above, the
               average temperature can be reported as the normal
               thermostatic setting of the box or ambient temperature,
               whichever is greater.

     (7)  Determine and report the barometric pressure by maintaining
          a barometer on-site, or in the near vicinity.  Read and
          report the barometric pressure each sampling period.  Alter-
          natively, the pressure can be obtained from the nearest"
          weather station provided the altitudes of the weather station
          and sampling site do not differ by more than about 61 m
          (-200 ft).

          The barometric pressure seldom varies more than 2 or 3 per-
          cent from a mean value for a given site.  Therefore, unless
          a high degree of accuracy is required, an average pressure
          derived from 20 to 30 days of data can be used as the
          barometric pressure for that site.  Also, barometric pressure
          is not required when a critical orifice is used to control
          the flow rate.

Sampling Handling (Step 9)

     (1)  Remove the exposed absorber from the sampling train.  Remove
          the accordian tubing (from the galss manifold) from the
          absorber first.  Check the absorber and if any of the reagent
          has evaporated, use fresh absorbing reagent to bring it up
          to the 50 ml mark (24-hour sample).  Record on the Sample
          Record Sheet the quantity of absorbing reagent (mX,) or state
          under "Remarks" that there was no evaporation.  If the absor-
          ber is estimated to have less than 35 mfc the sample should be
          invalidated by so stating on the record sheet.  The absorber
          and record sheet should be forwarded to the supervisor.  If
          there are signs that indicate that part of the absorbing
          reagent was forced out of the absorber into the system,
          absorbing reagent should not be added and the situation noted
          on the Sample Record Sheet.

     (2)  Replace the tube caps on the exposed absorber.  Be sure to
          place the cap over the impinger tube opening near the painted
          side of the absorber lid first.  Press both caps on firmly
          and place the absorber in the shipping block.  Note:  where
          glass impingers are used replace any evaporated absorbing
          reagent, shake thoroughly, then transfer the exposed reagent
          to a test tube with a teflon-lined, threaded cap.  Place the
          test tube in the shipping block.

                                    35

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      (3)  If a critical orifice was used, disconnect the base end
          of the hypodermic needle from the metal exhaust manifold
          and remove the needle from the rubber stopper and place
          the needle in the shipping block with the exposed
          absorber.  Note:  The needles must be returned with the
          absorber that it was used with.

      (4)  Record on the Sample Record Sheet any unusual activities
          or conditions near the site such as fires involving
          burning coal or oil, large coal burning power plants,
          smoking stacks, rain, snow, fog, inversions, or other
          conditions that may affect the pollution level.

      (5)  Fill out the Sample Record Sheet in duplicate.  Fold the
          original copy and wrap around the absorber in the shipping
          block.  File the duplicate copy in the site log book.

      (6)  Deliver the sample to the laboratory or pack the absorber
          (and critical orifice) in a mailing container, affix the
          return mailing label, and mail promptly.

SAMPLE ANALYSIS

Verify Documentation (Step 10)

Check the Sample Record Sheet for any missing information that would
invalidate the sample.  If sufficient information is not available and
cannot be obtained from the field personnel, the sample should be invali-
dated at this point.  Visually check the absorber to see if it has 50 m£
of reagent.  If it does not have 50 m£, check for signs of leaks and check
the Sample Record Sheet for comments by the field operator.  If the
absorber is low and the field operator's entry on the Sample Record Sheet
says that there was 50 m£ when mailed, continue the analysis.  If the
absorber is visually low and there are no consents by the field operator
on the Sample Record Sheet, invalidate the sample.  Also, any 24-hour
sample that required more than 15 m£ of TCM to be added should be
invalidated.

Recalibrate the Critical Orifice (Step 11)

Recalibrate the critical orifice in the same manner that it was calibrated
originally in Step 2.  Record the new K value in the calibration log book.
If the final K value differs from the initial K value by more than 10 per-
cent, the sample should be invalidated.  Compute the percent deviation by

                                        K  - K
                   percent difference = 	-	 * 100
                                           Ki

where   K± = the initial K value (cm3/min)/(°K)1/'2

and     Kf = the final K value (cm3/min)/(°K)1/2.


                                    36

-------
If the final K value is within 10 percent of the initial K value, compute
the average flow rate for the sampling period by:
                                           •, /-,
                _                            o
where           Q = the average flow rate (cm /rain) ,

        KA and Kf = initial and final calibration K values,
                    respectively,

and            T, = average temperature reported by field
                    operator, °K.

Use Q in subsequent calculations.

Reagent Preparation For Analysis (Step 12)

Prepare reagents for analysis according to the directions given in
Subsection 6.2 of the Appendix.   Class A volumetric glassware should be
used.  The analytical balance should be checked before preparing a batch
of reagents by weighing a standard weight between 1 and 3 grams.  If the
measured and actual weights agree within +0.4 mg proceed with the
preparation.  Record the actual and measured weights in the laboratory
log book.  If the weights differ by more than + 0.4 mg, continue the
preparation but report to the supervisor that the balance calibration needs
checking.  This should be carried out by a manufacturer's representative.

Sulfamic Acid (0.6 percent) - Dissolve 0.6 g sulfamic acid in a 100 mi
volumetric flask with water, and bring to mark.  Keep in a glass-stoppered
flask while not in use.  Prepare fresh daily.

Formaldehyde (0.2 percent) - Dilute 5 mi formaldehyde solution  (36-38 per-
cent) to 1,000 ml with distilled water.  Keep in a stoppered container
while not in use.  Prepare fresh daily.

Stock Iodine Solution (0.1 N) - Place 12.7 g iodine in a 250 mi beaker; add
40 g potassium iodide and 25 mi of water.  Stir until all is dissolved,
then transfer to a 1,000 mi flask and dilute to the mark with distilled
water.  Keep the solution in a glass-stoppered, dark, bottle and store in
a cool place.

Working Iodine Solution ^0.01 N) - Prepare approximately 0.01 N iodine
solution by diluting 50 mi of stock solution to 500 mi with distilled water.
Keep in a glass-stoppered, dark, bottle or flask.  It is recommended that
this solution be prepared fresh from stock daily.

Starch Indicator Solution - Triturate 0.4 g soluble starch and  0.002 g
mercuric iodide (preservative) with a little water, and add paste slowly
to 200 mJl boiling water.  Continue boiling until solution is clear; cool,
and transfer to a glass-stoppered bottle.  Alternatively a solution of
stabilized starch for volumetric determinations can be purchased
commercially.                       07

-------
Stock Sodium Thiosulfate Solution (0.1 N) - Prepare a stock solution by
dissolving 25 g sodium thiosulfate (Na.S.O  • 5H.O) in 1,000 mA freshly
boiled, cooled, distilled water and add 0.1 g sodium carbonate to the
solution.  Allow the solution to stand 1 day before standardizing.  To
standardize, accurately weigh to the nearest 0.1 mg, 1.5 g primary standard
potassium iodate (KIO,) dried at 180° C for 1 hour and cooled in a dessicator.
Dilute to volume in a 500 m£ volumetric flask.  To a 500 m£ iodine flask,
pipet 50 m£ of iodate solution, add 2 g potassium iodide and 10 mil of 1 N
hydrochloric acid.  Stopper the flask.  After 5 minute titrate with stock
thiosulfate solution to a pale yellow.  Add 5 mJl starch indicator solution
and continue the titration until the blue color disappears.  Calculate the
normality of the stock solution as follows:
                             N -   x 2.80
                                 M


where   N - normality of stock thiosulfate solution,

        M » volume of thiosulfate required, m£,

        W - weight of potassium iodate, grams,
              3
  j  0 80   10  (conversion of g to mg) x Q.l (fraction iodate used)
               35.67 (equivalent weight of potassium iodate)


Keep this solution stored in a glass-stoppered bottle or flask.

This solution should not be used without being restandardized if stored  for
more than one month.

Sodium Thiosulfate Titrant (0.01^ N) - Accurately pipet 100 m£ of the stock
thiosulfate solution into a 1,000 mH volumetric flask.  Dilute to  the mark
with freshly boiled, cooled distilled water.  This 0.01 N solution is not
stable, and must be prepared fresh daily from the stock thiosulfate
solution.  Keep in a glass-stoppered flask or bottle when not in use.


           Normality - Normality of stock solution x 0.100.
Standardized Sulfite Solution  for Preparation of Working  Sulfite  -
TCM .Solution - Dissolve 0.3  g  of sodium metabisulfite  (Na.,S03)  in
500 mJl of recently boiled, cooled,  distilled water.   (Sulfite  solution
is unstable; it  is therefore important to  use water  of the  highest  purity
to minimize this instability.)  This  solution contains the  equivalent of
320 to 400 pg/mJl of SO-.  The  actual  concentration of  the solution  is
                                     38

-------
determined by adding excess iodine and backtitrating with standard sodium
thiosulfate solution.  To backtitrate, pipet 50 m£ of the 0.01 iodine into
each of two 500 m& iodine flasks  (A and B).  To flask A  (blank) add 25 ml
distilled water, and to flask B (sample) pipet 25 mSL sulfite solution.
Stopper the flasks and allow to react for  5 minutes.  Prepare the working
sulfite-absorbing reagent solution (see below) at the same time iodine
solution is added to the flasks.  By means of a buret (50 mil buret)
containing standardized 0.01 N thiosulfate, titrate each flask in turn to
a pale yellow.  Then add 5 m£ of  starch solution to the flask and shake
thoroughly.  Continue the titration until  the blue color disappears.  Store
in a glass-stoppered bottle or flask.

Working Sulfite-TCM Solution - Pipet accurately 2 m£ of the standard
solution into a 100 mJl volumetric flask and bring to mark with 0.04 M
absorbing reagent.  Calculate the concentration of sulfur dioxide in the
working solution:
                yg S02/m4 = (A~B)(N)(32,000) x
where   A = volume thiosulfate for blank, m&,

        B = volume thiosulfate for sample, m£,

        N = normality of thiosulfate titrant,

   32,000 = milliequivalent weight of SO-, pg, and

     0.02 = dilution factor.
This solution is stable for 30 days if kept at 5°C (refrigerator).  If not
kept at 5°C prepare fresh daily.

Pararosaniline Reagent - To a 250 m£ volumetric flask add 20 mX, stock
pararosaniline solution.  Add an additional 0.2 mA stock solution for each
percent the stock assays below 100 percent.  Then add 25 m& of 3 M phosphoric
acid and dilute to volume with distilled water.  This reagent stored in a
glass-stoppered bottle is stable for at least 9 months.
 This equation as written in Subsection 6.2.9 of the Appendix is in error
 by a factor of 25.
                                    39

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Preparing a Purified Pararosaniline  Stock  Solution -  In preparing a
purified pararosaniline stock  solution  the method referenced  in
Subsection 6.2.10.2 of the Appendix  for purifying the dye  is  as  follows
(Ref.  2):

      (1)  Place  100 m£ each of 1-butanol and IN HCl in a large
          separatory funnel (250 m£) and allow to equilibrate.
          Note:  Certain batches of  1-butanol contain oxidants
          that create an SO. demand.  Before using check by

          placing 20 m£ of 1-butanol with  5 ml of 20  percent
          potassium iodide (KI) in a 50 mil. separatory funnel  and
          shake  thoroughly.  If a yellow color appears in  the
          alcohol phases, redistill  the 1-butanol from silver
          oxide, and collect the middle fraction, or  purchase a
          new supply of 1-butanol.

      (2)  Weigh  100 mg of pararosaniline hydrochloride (PRA), in a
          small  beaker.  Add 50 m£ of the  equilibrated acid (drain
          the acid from the bottom of the  separatory  funnel in (1)
          above) to the beaker and let  stand for several minutes.

      (3)  To a 125 m£ separatory funnel, add 50 m£ of the  equili-
          brated 1-butanol (draw the 1-butanol from the top of the
          separatory funnel in (1) above).  Transfer  the acid
          solution (from (2) above)  containing the dye to  the funnel,
          and extract.  The violet impurity will transfer  to  the
          organic phase.

      (4)  Transfer the lower (aqueous phase) into another  separatory
          funnel and add 20 m£  of 1-butanol; extract  again.

      (5)  Repeat the extraction procedure with three  more  10  m£
          portions of 1-butanol.  This  procedure usually removes
          almost all of the violet impurity that contributes  to
          the blank.

      (6)  After  the final extraction, filter the acid phase through
          a cotton plug into a  50 m£ volumetric flask and bring  to
          volume with 1 N HCl.  This stock reagent will be yellowish
          red.

Assaying the PararosanilineJStock Solution - The concentration of
pararosaniline hydrochloride (PRA) need be assayed only once  after prep-
aration.  It is also recommended that commercial solutions of pararosaniline
be assayed when  first purchased.  The assay procedure is as follows (Ref. 2):

      (1)  Prepare a buffer stock solution with a pH of 4.69 by
          dissolving 13.61 g of sodium  acetate trihydrate in
          distilled water in a  100 m£ volumetric flask.  Add
          5.7 m£ of glacial acetic acid and dilute to volume with
          water.
                                    40

-------
     (2)   Take 1 m& of the stock solution obtained from the
          purification process or from a commercial source and
          dilute to the mark in a 100 m£ volumetric flask with
          distilled water.

     (3)   Transfer a 5 m£ aliquot to a 50 m£ volumetric flask.
          Add 5 mJi, of 1M acetate-acetic acid buffer solution from
          (1)  above and dilute the mixture to the mark with
          distilled water.  Let the mixture set for 1 hour.

     (4)   Measure the absorbance at 540 nm with a spectrophoto-
          meter.  Compute the percent of nominal concentration
          of PRA by
                             % PRA
                                         K
                                       W
          where   A = the measured absorbance of the final
                      mixture (absorbance units),

                  W = the weight in grams of the dye used in the
                      assay.  For example, 100 mg of dye was used
                      to prepare 50 mX. of solution in the purifica-
                      tion procedure and 1 mJl of the solution was
                      used in the assay, then W = 0.002 g

                      (•—• x 100 mg).  When obtained from commercial
                      sources use the stated concentration to compute W.

                  K = a constant whose value has to be determined
                      for a given spectrophotometer and associated
                      equipment.  For example, when using 1-cm
                      optical path length cells, 0.04 mm slit width
                      in a Beckman DU spectrophotometer, K = 21.3.

          Note:  For other spectrophotometers and equipment, K can
                 be determined by assaying a batch of PRA of known
                 purity (i.e., in the above equation % PRA is known,
                 A and W is measured then K can be calculated).

Develop a Calibration Curve (Step 13)

Procedure With Sulfite Solution - Develop a calibration curve as directed
in Subsection 8.2.1 of the Appendix, page 114.  Obtain at least 6 data
points and construct the best-fit, straight line using the method of
least squares.  Check the calibration curve to determine if it satisfies
the following requirements:
                                    41

-------
      (1)  The slope Is between 0.03 + 0.002 absorbance unit/
          yg SO..  A slope outside these limits indicates  that

          an Impure dye or an improperly standardized sulfite
          solution was used.  The calibration should be repeated
          and if the slope/remains outside the above limits, the
          sulfite solution should be restandardized and the purity
          of the dye checked to determine the trouble.  If
          necessary, prepare all new reagents and develop  a new
          calibration curve.

      (2)  The calibration curve Intercept on the absorbance axis
          is between 0.163 + 0.039 with the calibration performed
          at room temperature.  The above numbers represent the
          mean and 3cr values for the calibration curve intercept
          from a collaborative test of the method (Ref. 6).


          If the Intercept is outside the above limits and the room
          temperature is approximately 22°C, the calibration curve
          should be repeated after checking the spectrophotometer
          for proper calibration.  If the intercept remains outside
          the above limits, with the temperature ~22°C, chemicals
          and laboratory procedure should be checked before preparing
          new reagents and developing a new calibration curve.

          The process of checking and repeating should be  continued
          until a calibration curve with an intercept within the
          above limits is obtained.

      (3)  Check each calibration point and repeat any point deviating
          more than 0.8 yg SO, (20 value for measuring control
          samples from Ref. 6) from the best-fit curve for a given
          absorbance value.  Average the two values and replot the
          point.  Repeat until all points are within 0.8 yg SO. of
          the best-fit curve.

      (4)  Compute the reciprocal of the slope and record on the
          calibration curve.  File the calibration curve in the
          calibration log book after having the supervisor accept
          the results by signing and dating the calibration curve.

A new calibration curve must be developed when:

      (1)  a new batch of reagents is made, or

      (2)  a control sample cannot be measured within +1.2 yg S0«

          of its actual value when the control sample is prepared as
          directed in Subsection 8.2.1 of the Appendix, page 114.
                                    42

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Procedure with BO 2 Permeation Tubes - Procedures for generating standard
atmospheres and preparation of a calibration curve are given in Sub-
section 8.2.2 of the Appendix.  SO. permeation tubes having nominal shelf
lives (at 22°C) ranging from 4 to 24 months are commercially available
(Ref. 3).  Tubes with a certified permeation rate can be obtained from the
National Bureau of Standards (NBS) .  Alternatively permeation tubes may be
prepared and calibration. However, this should only be attempted by
experienced personnel in a well-equipped laboratory.

CatibMvUon orf SO* permeation tube* - A detailed discussion of the required

apparatus and procedures for preparation and gravimetric calibration of
permeation tubes is given in Reference 4.  A method for volumetric ally
calibrating SO- permeation tubes is given in Reference 5.  Permeation rates
determined both volumetrically and gravimetrically for 4 tubes showed
volumetric determinations averaging 3 percent higher than gravimetric
determinations (Ref. 5).

The use of either of the above techniques requires a trained/experienced
operator, therefore, step-by-step procedures are not attempted here.  The
operator should refer directly to the above references for guidance.
            chuck - A permeation tube, whether prepared and calibrated in
the laboratory, purchased from a manufacturer with a stated permeation
rate, or obtained from the NBS with a certified permeation rate, should
be checked periodically throughout its useful lifetime.  A permeation tube
to be used continuously at a given temperature can be monitored in the
following manner.
                             ;
     (1)  Equilibrate the tube at the temperature it is to be
          used.

     (2)  Weigh the tube to the nearest 0.1 mg with an analytical
          balance sensitive to 0.01 mg.

          The tube should be handled with teflon-tipped forceps
          with special care exercised not to expose the tube to
          dust or other contaminants.  Also, any static charge
          should be removed from the tube.

     (3)  Record the weight to the nearest 0.1 mg, the date and
          time of weighing to the nearest minute in the cali-
          bration log book for that permeation tube.

     (4)  The tube should be reweighed at intervals equivalent
          to 1/10 of the expected life of the tube or, once a
          month, whichever is shorter.
                                    43

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      (5)   For  each new weighing compute a  permeation  rate using
           the  previous weighing and  the elapsed  time.   Record
           this value  in  the calibration log .book.

      (6)   Compute the percent deviation from the stated or
           certified value by
                                       P   - P
                   percent deviation - -~	 x  100
                                           a
          where   P  • actual  (certified)  permeation  rate
                       (ug/min)

          and     P  = measured permeation rate  (vig/min).


With proper handling and use ?  an  SO. permeation  tube  usually maintains  a
constant permeation rate (at a constant temperature)  as  long as  any
liquid is visible in the tube.  Therefore, a drop  in  the permeation  rate
indicates that the tube has been  damaged or that the  liquid  S0?  is nearly
gone.  It is suggested that the certified  or stated permeation rate  be
used as long as the measured rate is within +_ 5 percent  of the original
value.  If the measured permeation rate is less than  95  percent  of the
stated or certified permeation rate, the tube should  be  replaced if  there
is little or no liquid SO- in  the tube.  If the tube  still has a good
supply of liquid SO-, the new  measured permeation  rate should be used and
the tube reweighed at time intervals equivalent to a  weight  loss of  about
10 mg as computed by the permeation rate until 3 successive measured
permeation rates agree within  + 5 percent  of the average value of the three.
The average value should be used  as long as future checks are within
+ 5 percent.

PeveCojatng a. caJUJbJULtion. CUAve. -  Develop and construct a calibration curve
according to the directions given in Subsection 8.2.2 of the Appendix,
page 114.

Check each point on the calibration curve and redo any point  that deviates

more than * (0.8 yg SO-) from  the best-fit curve.  Replot the average of
the old and new values and construct a new best-fit curve.   Continue the
replication until the average  of  the two most recent  measurements falls
within + (0.8 ug SO.) of the best-fit curve.

Determine the total ug S0_ in  the sample by multiplying  the  known concen-
                                                      3
tration of the calibration apparatus output (yg S0_/m )  times the total volume
                             3                    L
of calibration air sampled (m  ).

-------
Compute the reciprocal of the calibration curve slope and record the value
on the calibration curve.  File the curve in the calibration log book
after it has been dated and signed by the supervisor.

A new calibration must be performed when:

     (1)  a new batch of reagents are prepared, or

     (2)  when a control sample cannot be measured within
          + (1.2 yg SO^) of its actual value when prepared
          with an SCL permeation tube.

Colorimetric Analysis (Step 14)

Prepare the sample, reagent blank, and control sample as directed in
Subsection 7.2 of the Appendix, page 114.

Set the spectrophotometer to a wavelength of 548 nm.  Allow at least
5 minutes for the spectrophotometer to warm up.  If necessary, adjust the
zero control to bring the meter needle to 0 on the percent transmittance
scale.   Standardize the light control by inserting a cell filled with
distilled water into the sampler holder and adjusting the light control
as required, until the meter reads 100 percent transmittance.  The complete
transmittance scale should be checked with a calibrated set of filters from
the National Bureau of Standards any time a control sample cannot be
measured with +1.2 yg S0_ of its known value.

It is recommended that a reagent blank and control sample be measured
before each set of determinations.  Record the absorbance value of the
reagent blank and the total yg S0? measured for the control sample in the
data log book with the time to the nearest hour.  If the absorbance blank
is within + 0.03 absorbance unit of the calibration curve absorbance
intercept and, if the measured value of the control sample is within
+1.2 yg SO,, of the actual value, proceed to analyze the field samples.

If the reagent blank and/or control sample falls outside the above limits
the reagent blank, control sample, and calibration curve should be checked
by replication as necessary to satisfy the above limits before analyzing
field samples.

It is recommended that when first implementing a quality assurance program
the oH of the final solution be measured for a sample from each
sampling site.  If the pH is less than 1.4 or greater than 1.8, the sample
should be invalidated and reported to the supervisor.  If the pH is
between 1.5 and 1.7, accept as good and if the pH is between 1.4 and 1.5,
or 1.7 and 1.8, the exact pH value should accompany the reported concen-
tration value for that sample.  In any case, checks should be made in an
effort to determine why the pH was outside 1.6 + 0.1 and corrective action
taken.
                                    45

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The pH should seldom, if ever, deviate from 1.6 + 0.1, but large errors
result if it does.  Therefore, it is suggested that the pH of the final
solution be checked for 1 sample a month for each sampling site.  Report
the measured pH to the supervisor and record the pH value with the site
identification data in the laboratory log book.

Record all measured values (i.e., reagent blanks, control samples,
samples) in sequential order in the data log book.  The date and time
should be recorded with each set of determinations.  The reagent blank
should only be used with the set of determinations in which it was
measured.

DATA PROCESSING

Perform Calculations (Step 15)

Rotameter - When a rotameter is used to measure the flow rate, perform the
following calculations.

     (1)  Obtain the rotameter reading, I  and I,, average temper-

          ature, T,, average pressure, Pf, and sampling period time

          as reported on the Sample Record Sheet by the field
          operator.

     (2)  From the rotameter calibration curve determine the K values
          for readings of I  and lf.

     (3)  Compute the average flow rate, Qf, at field conditions by
     (4)  Calculate the volume sampled, V,, at field, conditions by
                               V£ = Qf * t
          where t is the sampling period time in minutes.

     (5)  Correct the sampled volume to volume, VR, at reference
          conditions by
             V*> = Vf(cm > X     X          X 10
     (6)  Compute the average measured SO. concentration as directed
          in Section 9.2 of the Appendix, page 114.

                                    46

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Critical Orifice -  When a critical orifice is used to control flow rate
perform the following calculations.

      (1)  Obtain Q as computed in Step 11, page 36.  Also, obtain
          the sampling period time, t, the average temperature, I,,
          and the average pressure, P.., as reported by the field
          operator.

      (2)  Compute the volue, V,t sampled at field conditions by


                               Vf = Qf x t


          where t is the sampling period time in minutes.

      (3)  Correct the sampled volume to reference conditions by
              VRU) = Vf(cm3) x ^x |2t  10~3 (£/cm3).
                                                                o
     (4)  Compute the average measured SO. concentration in pg/m

          as directed in subsection 9.2 of the Appendix, page 114.

Document and Forward Data (Step 16)
                                               o
Record the average concentration of S0_ in pg/m  with required identifying

information on the appropriate SAROAD Data Form.  See Users Manual:  SAROAD
(Storage and Retrieval of Aerometric Data), APTD-0663, for detailed
instructions for accomplishing this.  The original calculations should be
filed in the operational data log book.

SPECIAL CHECKS FOR AUDITING

Proper implementation and conduct of an auditing program will allow one to
estimate data quality in terms of precision and accuracy at a given level
of confidence.  To realize maximum benefits from an auditing program, it
should be conducted independently of the routine operation of the sampling
network.  That is, checks should be made by individuals other than the
regular operator.  Furthermore, the checks should be performed without any
special preparation or adjustment of the system (see page 96 for further
discussion) .

It is felt that in conjunction with the special checks given in the
operating procedures three audit checks will be sufficient to properly
assess data quality.  The checks Include:
                                    47

-------
     (1)  a check of the average flow rate or volume of air
          sampled for sample collection,

     (2)  measurement of control samples to evaluate the
          analysis process, and

     (3)  a data processing check to evaluate calculation
          and recording errors.

A checking or auditing level of 7 checks (n = 7) out of 100 sampling periods
(N = 100) is used here for illustration purposes when sampling is carried
out on a daily basis.  For cases where one sample is collected every sixth
day, a minimum auditing level of 1 check per month is recommended.  This
would result in an auditing level of approximately 3 checks (n = 3) for a
lot size of 15 (N = 15) for data reported quarterly.  The supervisor will
specify the auditing level to be used according to local monitoring needs.

Directions for performing each of the checks are given here.  Proper use
of the resulting data along with desirable control limits are given in the
Supervision Manual starting on page 62.

Flow Rate/Volume Check

Volume Check - The volume of air sampled can be checked with a calibrated
wet test meter for 30-minute and 1-hour sampling periods with approximate

flow rates of 1000 cm /m (1 £/min) and 500 cm /min (.5 fc/min) respectively.
Note:  A flow rate of 500 cm /min is below the normal range of wet test
meters.  Hence, the meter must be calibrated at this exact flow rate
against a soap-bubble meter.  If the meter accuracy varies from check to
check by more than + 2 percent, it should not be used for this low flow
rate.

The regular operator prepares the sampler for collecting a sample in the
usual manner recording usual site parameters such as temperature and
pressure.  If a critical orifice is used in the sampling train the person
performing the check should provide a calibrated orifice.  The sampler
is allowed to run for 30-minutes of 1-hour as appropriate.

Compute the volume of air measured by the wet test meter corrected to
reference conditions by
                                            m
                                    48

-------
where   VR(C) = volume measured by wet test meter at  reference
                conditions, £,

           V  = volume measured by wet test meter at  T  and
            m   P   £                                 m
                 m'  '

           P  = barometric pressure plus meter pressure read
                from the manometer, mmHg,

and        T  = temperature of liquid in wet test meter,  °K.


Compute the volume of air sampled as measured by the  rotameter/critical
orifice and correct to reference conditions according to  the procedure in
step 15, page 46.  Designate this volume as V (0).
                                             K
Compute the percent difference in the two volumes by
                             V (C) - V  (0)
                                 Vc>
Report the values of Vn(C), V^CO), and d with site  identification data,  date,
                      K      K
and signature of person performing the check to the supervisor.

The. Cample. cotte.cte.d da>u.ng the. c/iecfe u> not a. vatid sample. and Ahoutd be.
4.n\jatida£nd and ^ofiwaAdad to the.
If d from the above calculations is equal to or greater  than 9  the  sampling
train including rotameter/critical orifice should be checked and corrective
action taken before sampling is resumed.

 Flow-Rate Check - For 24-hour  samples a flow-rate check is recommended as
 a means  of auditing the sample collection phase of the measurement process.
 The  check is  performed as follows:

      (1)   The regular operator prepares the sampler for sample
           collection as usual.  This includes filling in the
           Sample Record Sheet.

      (2)   The individual performing the audit inserts a cali-
           brated rotameter in  the sample inlet line just
           upstream of the outside filter (see Figure 8) .

      (3)   With the calibrated  rotameter in place the sample is
           collected in the usual manner.
                                     49

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      (4)   The individual performing  the  audit  reads  the  cali-
           brated  rotameter before, I*  and after,  I*,  the sampling

           period  and  at one point, preferably  the midpoint, during
           the sampling period,  I*.

      (5)   Following the procedure given  in Step 15,  page 46, for
           rotameters, calculate the  volume at  reference  conditions
           for the calibrated rotameter,  V (C).  In this  case the
                                         K.
           equation for computing the average flow rate is
                       ' + K' + Kl\ /I' + I1
                       i	i	f)  _i	s
                           3     / V      3
      (6)  Compute the sampled volume, VD(0), measured by the
                                       K.
          regular rotameter/critical orifice and correct to
          reference conditions according to the procedure given
          in Step 15, page 46.

      (7)  Compute the percent difference by
                            vc> -
                                vR(0
     (8)  Record l!, I', I', I., I,, and d and forward to the
                  i   m   t   i   i
          supervisor.

     (9)  If d is equal to or greater than 9, trouble shooting
          should be performed and corrective action taken before
          sampling is resumed.


Measurement of Reference Samples

Measurement of a reference sample prepared independently of normal
operations can be used to evaluate the precision and accuracy of the
analysis phase of the measurement process.  A reference sample as used
here refers to a sample prepared by an individual other than the regular
operator using reagents prepared independent of those used for normal
operations and used for auditing purposes.  A control sample as referred
to in the operating procedures implies a solution prepared by the regular
operator from the normally used reagents and used periodically to verify
that the analysis process is under control.
                                    50

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The procedure for performing the check is given below.  The frequency of
performing the check will be specified by the supervisor.  Further
discussion is given in the Supervision Manual on page 63»

     (1)  Prepare a reference sample with a known concentration in
          the same manner as was used when developing a calibration
          curve (see Section 8 of the Appendix).  The concentration
          should be varied over the range of normally measured
          values from audit to audit.

     (2)  Have the regular operator to measure the reference sample.
          The operator must not know the true concentration of the
          reference sample and preferably not know that it is a
          reference sample.

     (3)  Obtain the operator's finding (yg S0_)  and the true
                                              L m
          concentration (yg SO-)  of the sample and compute the
          difference by         c
                        d = (yg SO.)  - (yg SO.)
                                  L m         z c
     (4)  Record (yg SO-) , (yg SO.)  and d and forward to the
                       ^ m        ^ c
          supervisor.

          It is recommended that the supervisor maintain a record
          of the d values in chronological order and that analysis
          be stopped, checks made to determine the likely cause(s),
          and corrective action taken before the analysis is
          resumed anytime:

          (a)  a d value equal to or greater than 1.2 yg SO-
               is observed,

          (b)  two consecutive d values (i.e., results from two
               consecutive audit checks) exceed +0.8 yg SO  in
               the same direction, or

          (c)  three consecutive d values (i.e., results from three
               consecutive audit checks) exceed +0.4 yg SO- in the
               same direction.

     (5)  If the control sample measurement was outside the above
          limits, the calibration curve should be checked by
          measuring a reagent blank and control sample.  If
          necessary, a new calibration curve should be developed
          and other corrective actions taken as deemed necessary.

          After corrections are made, a new reference sample should
          be measured and, if acceptable, analysis resumed.

                                    51

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     (6)  If the supervisor reports that the reference sample
          measurement of (A) above was within limits, continue
          normal operations.

Data Processing Check

In auditing data processing procedures, it is convenient and allows for
corrections to be made immediately if checks are made soon after the
original calculations have been performed.  In particular, this allows
for possible retrieval of additional explanatory data from field personnel
when necessary.

The check must be independent; that is, performed by an individual other
than the one who originally reduced the data.  The check is made starting
with the raw data and continuing through recording the concentration in
    o
yg/m  on the SAROAD form.

If the mass concentration of SO. computed by the check differs from the
original value by as much as + 3 percent, all samples collected since the
previous audit are checked and corrected.  The check value is always
reported as the correct value.

Record the check and original values in the operational data log book
and report the values to the supervisor.

SPECIAL CHECKS TO DETECT AND IDENTIFY TROUBLE

The following checks are recommended as a means of checking the adequacy
of different phases of the measurement process.  The checks are:

     (1)  estimate the average temperature environment experienced
          by a sample between collection and analysis,

     (2)  interference checks,

     (3)  measurement of the pH of the final solution at time of
          analysis,

     (4)  visual check of the volume of absorbing reagent in the
          exposed absorber before analysis, and

     (5)  a check on the accuracy of the sampler timer.
                                    52

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Errors resulting from any one of the above areas would not be detected by
the auditing process.  However, errors from all except the first source
should be small if the suggested operating procedures are being followed.
Checks 2 through 5 should be performed for each sampling site when:

     (1)  a quality assurance program is first initiated in order
          to identify potential problem areas, and

     (2)  periodically thereafter by the supervisor as an overall
          check on the measurement process.

Check number 1 should be made for each site when:

     (1)  a quality assurance program is first initiated, and

     (2)  when any change in sample handling or shipping occurs.

Average Temperature Environment of Sample Between Collection and Analysis

For samples that spend several days in transit from the sampling site to
the analysis laboratory, the loss of SO- at elevated temperatures can be

significant (Ref. 2).  From the geographical location of the site and
laboratory, the season of the year, and the mode of transport make a rough
estimate of the average temperature that the sample will be exposed to from
the completion of the sampling period to the time of analysis.  It is
recommended that the following corrections be applied to the measured
concentration at reference conditions for any sample with an unrefrigerated
time lapse greater than 1 day between collection and analysis:

     (1)  If the estimated average temperature is 5°C or less
          no correction is necessary.

     (2)  If the estimated average temperature is between 5 and
          22°C the corrected concentration should be calculated
          by (Ref. 2)
                                     (lag S02/m3)
                      (yg
          where   ( g S00/m )  = the corrected concentration of
                        2    c   so2,
                           3
                  ( g S0_/m )  = the measured concentration of
                        2    m   so2,

          and                D = the elapsed time between collection
                                 and analysis in days.
                                    53

-------
      (3)  If the estimated average temperature is between 22 and 28°C
          the corrected concentration is calculated by (Ref. 7)
                                     (pg SO /m3)
                     (yg S07/mJ)  = 	     m
                                c   1.0 - 0.02 x
These corrections are only rough estimates.  The most desirable situation
would be to have D very small or the temperature controlled at a known level.

Measurement of pH of Final Solution

The absorbance of a sample is highly sensitive to the solution pH (Ref. 2).
Therefore, it is suggested that samples from each site be checked initially
to determine if the ambient atmosphere contains pollutants in sufficient
quantities to affect the pH of the final solution and thereafter as a check
on the reagents used in the analysis when control samples cannot be
measured within specified limits.  The pH should be measured }ust prior to
the analysis.  Any sample having a pH outside of 1.6+0.1 should be investi-
gated and corrective action taken.  The primary suspect would be an error in
the quantity of phosphoric acid added to the sample.

Interference Checks

Control samples and reference samples with known concentrations of S0» are

measured to evaluate the analysis phase of the measurement process.  In
addition to those measurements, it is recommended that periodically
reference samples be spiked with one or more of the principal known inter-
ferences to evaluate the effectiveness of chemicals and procedures used to
reduce or eliminate the interference.

Spiked samples should be used when the ambient atmosphere is known to
contain higher than normal concentrations of a particular interference
or any time the reported S02 values appear larger than expected from a
set of determinations.

One means of performing the check is as follows:

     (1)  Prepare two control samples with identical amounts of
          the working sulfite-absorbing reagent solution (see
          Subsection 6.2.9 in the Appendix).

     (2)  Spike one of the control samples with a known quantity of
          the interference of interest.

          (a)  Nitrates or nitrites can be used to prepare a
               solution of known concentration of nitrogen oxides.

          (b)  Salts of the heavy metal of interest can be used to
               prepare solutions of known concentrations for
               spiking the control sample.
                                    54

-------
     (3)  Have the operator measure a reagent blank, the unspiked
          control sample, and the spiked control sample in sequence.

     (4)  Compare the measured concentration of the two control
          samples by computing the difference
                   difference = (vg SO )  - (yg SO.)
                                      2 2         2
          where   (ug SO-)  = total measured concentration of the
                          1   unspiked sample,

                  (pg S0?)  = total measured concentration of the
                          2   spiked sample.
     (5)  If the difference is equal to or less than +1.2, it is
          assumed that there is no difference in the sample.

     (6)  If the percent difference is greater than the above
          limits the appropriate chemicals and procedures should
          be checked and corrective action taken to eliminate
          interferences.
Volume of Absorbing Reagent

An error in the volume of sample prior to analysis is transferred directly
to the measured concentration.

The operator removing the absorber from the sampling train is responsible
for replacing any absorbing reagent that was evaporated during sample
collection for 24-hour samples that have to be mailed to the laboratory.
The operator performing the analysis is responsible for bringing the
sample volume to the specified amount for samples delivered directly to
the laboratory from the field site.

Absorbers and associated Sample Record Sheets should be checked periodi-
cally just prior to analysis to determine if the sample volumes are
accurate and to see if the operating procedures are being followed.

Check of Sample Timer

In 24-hour samples an error of + 14 minutes represents an error in the
measured concentration of only 1 percent.  However, accurate timing is
essential for 30-minute and 1-hour samples.  If automatic timers are used
for the shorter time periods, it should be checked at least every six
months against a calibrated time piece such as a stop watch.  Alternatively,
an elapsed time indicator could be used in conjunction with an uncalibrated
timer.

                                    55

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Any deviation in the sample period time as measured by the standard and
that indicated by the regular means of measuring the time greater than
+ 1 percent from the standard timer should result in replacing the timer
or employment of a new technique for measuring the sampling period time.

FACILITY AND APPARATUS REQUIREMENTS

Facility

Primary facilities required for the pararosaniline method are a central
laboratory and individual sampling stations.  The laboratory should be
equipped for

     (1)  reagent preparation,

     (2)  storage of chemicals and reagents

     (3)  calibration of critical orifices or rotameters, and

     (4)  sample analysis.
The laboratory should be equipped with an automatic all-seasons air
conditioning unit capable of maintaining a pre-set temperature within
+ 3°C  (5°F).  It should also be equipped with a hood and  exhaust  fan
large  enough to accomodate  the acid bath used for cleaning  the glassware.

The sample collection unit  should include a dark box for  housing  the
bubbler and protecting it from direct sunlight.  Also,  the  box should be
thermostated to prevent condensed moisture from freezing  in the sampling
train  lines in cold weather.

Apparatus

Items  of equipment with approximate costs are listed in Table 1.  Each
item is checked according to whether it is 1) required  in the reference
method, 2) used to control  a variable or parameter, 3)  required for
auditing purposes, or 4) used to monitor a variable.  The permeation tube
setup  is. included as an alternate calibration method.
                                     56

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Table 1.  APPARATUS USED IN THE MANUAL PARAROSANILINE METHOD
Item of equipment
CALIBRATION
1. Flow-rate calibration unit
2. Wet test meter
3. Permeation tube calibration setup
4. Spectrophotometer calibration
unit
5. Set of standard weights
6. Soap bubble meter
SAMPLING
7. 24-hr sampling system
8. 30-min/l-hr sampling system
9. 24-hr timer
10. Midget impinger
11. 100 mJl threaded bubbler
12. Filter holder
ANALYSIS
13. Spectrophotometer (manual)
14. Analytical balance
15. pH meter and probe
16. Misc. glassware
17. Reagents (cost/100 samples)
Approx.
cost 1973

300
1,000
2,200
100
110
50

250
250
40
10
4
2

600-900
1,400
350
100
10
Assoc.
error

Calibration
Calibration
Calibration
Calibration
Calibration
Calibration













Ref.
method

/






/
/
/
/
/
1

/
/


^
Variable
Monitoring





/











/


Auditing
equipment


^



/














-------
 SECTION III               SUPERVISION WNUAL
GENERAL

Consistent with the realization of the objectives of a quality assurance
program as given In Section I, this manual provides the supervisor with
brief guidelines and directions for:

     (1)  the collection and analysis of information necessary for
          the assessment of high volume data quality,

     (2)  isolating, evaluating, and monitoring major components
          of system error,

     (3)  changing the physical system to achieve a desired level
          of data quality,

     (4)  varying the auditing or checking level to achieve a
          desired .level of confidence in the validity of the
          outgoing data, and

     (5)  selecting monitoring strategies in terms of data quality
          and cost for specific monitoring requirements.

This manual provides brief directions that cannot cover all situations.
For somewhat more background Information on quality assurance see the
Management Manual of this document.  Additional information pertaining
to the Pararosaniline Method can be obtained from the final report for
this contract and from the literature referenced at the end of the
Management Manual.

Directions are written in terms of a 24-hour sampling period with
reference to 30-minute and 1-hour sampling periods when appropriate and
an auditing level of n-7 checks out of a lot size of N=100 for illustra-
tion purposes.  Special instructions for auditing operations where
sampling is performed every sixth day are given also.  Information on
additional auditing levels is given in the Management Manual.

Specific actions and operations required of the supervisor in implement-
ing and maintaining a quality assurance program as discussed in this
Manual are summarized in the following listing.
                                    58

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(1)  Data Assessment

     (a)  Set up and maintain an auditing schedule.

     (b)  Qualify audit results (i.e., insure that checks
          are independent and valid).

     (c)  Perform necessary calculations and compare with
          suggested performance standards.

     (d)  Make corrections or alter operations when standards
          are exceeded.

     (e)  Forward acceptable qualified data, with audit results
          attached, for additional internal review or to user.

(2)  Routine Operations

     (a)  Obtain from the operator immediate reports of
          suspicious data or malfunctions.  Initiate corrective
          action or, if necessary, specify special checks to
          determine the trouble; then take corrective action.

     (b)  On a dally basis, evaluate and dispose of (i.e., accept
          or reject) data that have been identified as question-
          able by the operator.

     (c)  Examine operator's log books periodically for complete-
          ness and adherence to operating procedures.

     (d)  Approve sample record data sheets, calibration data,
          etc., for filing by operator.

     (e)  File auditing results.

(3)  Evaluation of Operations

     (a)  Evaluate available alternative monitoring strategies
          in light of your experience and needs.

     (b)  Evaluate operator training/instructional needs for
          your specific operation.
                               59

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ASSESSMENT OF DATA QUALITY

Procedures for implementing and maintaining an auditing program to assess
data quality are presented in this section.  Throughout this discussion
and the rest of this document, the term "lot" is used to represent a set
or collection of objects (e.g., measurements or observations), and the
"lot size" designated as N is the number of objects in the lot.  The
number of objects in the lot to be tested or measured is called the
"sample size" and is designated as n.  The term "auditing level," used
Interchangeably with "checking level," is fully described by giving the
sample size, n, and the lot size, N.

A valid assessment of a lot of SO. data generated with the manual
pararosaniline method can be made at a given level of confidence with
information derived from special checks of key operations in the measure-
ment method.  Figure 15 summarizes the quality control checks applied
at various check points in the measuring process.  Each check or opera-
tion is represented by a box.  They are in the order in which they would
be performed on a particular sample as it progresses through the process.

Boxes enclosed by heavy lines represent 100 percent sampling; i.e., these
checks are made on each sample passing through the system.  The two checks
enclosed by dashed lines are not scheduled at any given rate but are
carried out as specific events take place (e.g., a new batch of absorbing
reagent is prepared or at the beginning of a set of determinations).  The
remaining three checks are to be performed at the prescribed auditing
level.

All but one of the checks are treated on a go/no-go basis.  That is, a
standard or limit is defined and the lot or individual item is accepted
or rejected on the basis of the check results.  Certain rejected lots
or samples are corrigible; i.e., they are capable of being corrected.
Specifically, samples are corrected for delay between collection and
analysis and lots rejected because of data processing errors are
accepted after the errors have been located and corrected.  The one check
not treated on a go/no-go basis is the volume/flow-rate check.  This
check is performed at the prescribed auditing level.  Action for
correcting system deficiencies may be taken as the result of any one
check, however, there is usually no clear-cut way of correcting previous
data.  Therefore, results of this check are reported and used in
assessing data quality along with the results from measuring reference
samples as described in the Management Manual, page 96.  Also, in some
instances results from the data processing checks may be requested by
the manager.
                                    60

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                           I	1
                           !   MEASURE pH OF    I
                           I ABSORBING REAGENT  I
                           I                    I

                           L— T	J
                                CALIBRATE
                                FLOW RATE
                     CHECK THE pH OF A NEW BATCH OF ABSORBING
                     REAGENT BEFORE USE.   ACCEPT THE BATCH IF
                     3 < pH < 5.
                     CALIBRATE THE CRITICAL ORIFICE  BEFORE
                     EACH SAMPLING PERIOD.   CALIBRATE THE
                     ROTAMETER, IF USED,  PERIODICALLY.
                              CHECK SYSTEM
                                FLOW RATE
                     CHECK THE VACUUM GAUGE READING TO INSURE
                     CRITICAL FLOW WHEN CRITICAL ORIFICES  ARE
                     USED.  ACCEPT IF VACUUM IS  GREATER THAN
                     507 m*g.  CHECK AND ADJUST SYSTEM FLOW
                     RATE WHEN ROTAMETER IS USED.
      REPORT
'irV-"i
 TO  SUPERVISOR
                            VOLUME/FLOW-RATE
                                  CHECK
                     AUDIT THE VOLUME/FLOW RATE  ON  7  OUT  OF  100
                     SAMPLING PERIODS.   REPORT A DEFECT  IF
                     d,.  i 9 (SEE PAGE  71  FOR DEFINITION  OF  d, .)
                                SAMPLING
                                 PERIOD
                                TIME (T)
                     ACCEPT SAMPLE IF 23 <  T <  25 HOURS  FOR
                     24-HOUR SAMPLES.  OTHERWISE  INVALIDATE
                     THE SAMPLE AND INFORM  THE  SUPERVISOR.
                                 UNUSUAL
                               CONDITIONS
                          r
   MEASURE       I
REAGENT BLANK    ,
     AND         '
                          J  CONTROL SAMPLE
                     ACCEPT  IF NO UNUSUAL  CONDITIONS  ARE  EVIDENT.
                     E.G., ENTRAPMENT OF  ABSORBING REAGENT, LOSS
                     OF SAMPLE DURING HANDLING,  OBVIOUS EQUIPMENT
                     MALFUNCTIONS, ETC.
                                                      A REAGENT BLANK AND A CONTROL SAMPLE IS
                                                      MEASURED AT THE BEGINNING OF EACH SFT OF
                                                      DETERMINATIONS.
     REPORT


 TO SUPERVISOR
                                 MEASURE
                                REFERENCE
                                 SAMPLES
                              TIME BETWEEN
                           COLLECTION/ANALYSIS
                     AUDIT THE ANALYSIS PHASE BY  MEASURING  7
                     REFERENCE SAMPLES RANDOMLY DISPERSED AMONG
                     100 FIELD SAMPLES.   REPORT A DEFECT IF .
                     d2j i 1.2 u9 S02 (SEE  PAGE 73 FOR
                     DEFINITION OF d-,).
                     MAKE CORRECTION TO THE  MEASURED CONCENTRATION
                     FOR DELAYS BETWEEN COLLECTION  AND ANALYSIS.
                                  DATA
                               PROCESSING
                                  CHECK
                     REDO CALCULATIONS ON 7  OUT  OF  100  SAMPLES.
                     ACCEPT  THE  100 SAMPLES  IF:   1)  ALL CHECK
                     CALCULATIONS ARE  WITHIN + 3 PERCENT OF THE
                     ORIGINAL. OR 2) ALL  CALCULATIONS HAVE BEEN
                     REDONE  AND  CORRECTED.
                                REPORT TO
                               SUPERVISOR
                            AS VALID SAMPLES
                                                   REPORT ALL VALID SAMPLES TO THE SUPERVISOR.
                              ASSEMBLE DATA
                            INTO HOMOGENEOUS
                           LOTS OF 100 SAMPLES
                     SUMMARIZE  AND ATTACH AUDIT  RESULTS  TO
                     SAROAD FORM.
                                 FORWARD
                             FOR ADDITIONAL
                             INTERNAL REVIEW
FIGURE 15:  FLCH CHART OF QUALITY CONTROL CHECKS IN THE AUDITING PROGRAM
                                      61

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Required Information

For an auditing program as described above the required information for
evaluating data quality, includes results from the following checks:

    (1)  volume/flow-rate checks,

    (2)  reference sample measurement, and if requested,

    (3)  data processing checks.

Directions for performing the above checks are given in the Operations
Manual, page 47.  Directions for insuring Independence and proper randomi-
zation in the auditing process and for the evaluation of the results are
presented in this section.

Collection of Required Information

Volume/Flow-Rate Check - A volume check using a wet test meter is
recommended for  samples where the flow rate is 500 cm^/min. or greater.
A flow-rate check using a calibrated rotameter is recommended for samples
where the flow-rate is less than 500 cm^/min. procedure for performing
the check.  Samples from individual sites should be combined Into lots.
For sites where 50 or more samples are collected each quarter, a minimum
of 7 randomly spaced checks per quarter is recommended.  A minimum of 3
checks per quarter is recommended for sites operating every sixth day,
thereby generating 15 or les& samples a quarter.

Randomly select 7 sampling periods from the coming quarter for sites
where the lot size is expected to be as large as 50.  Record dates.
The operator should not be aware of when the checks are to be performed.
Remember that when volume checks are made the sample is invalid.  Hence,
the check should be made before or after the regular sample is collected.
The flow-rate check can be made on the actual sample.

For sites where the lot size is 15 or less, randomly select 1 sampling
period each month.  Record these dates and perform the checks as scheduled.
Directions for performing the check are given in the Operations Manual,
page 47.
          0^ data. - Obtain the audit results from the individual performing
the audit (see Section on "Special Checks for Auditing," page 47).

Using the check value, Vc^ and the value determined by the operator, V0j ,

compute the percentage difference by
                                    62

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where   V  . = the Volume measured by the wet test meter  (corrected
                                                 th
              to reference conditions) for  the j   check performed
              during an auditing period,

        V  . = the Volume measured by the regular method  (i.e., flow
         °-'   rate times the sampling period time) ,

and     d. . - the percent difference in the volumes measured for  the
               f~H
              j   check, the subscript 1 identifies the  check as
              being a volume or flow-rate check.


Report d-.., d..-, d.,, d ,, d   , d ,, d. _ and the auditing level on the  form

in Figure 16, page 65.

Measurement of Reference Samples - Reference samples prepared independent
of the normal operations are used to evaluate the analysis phase  of the
measurement method.
           0$ Ae^CAence AOmptu - Reference samples should be made using a
working sulfite-TCM solution  (see Subsection 6.2.9 in the Append' -.) that was
prepared independent, both personnel and chemicals, from the regularly used
solution.  Alternatively, reference samples can be prepared with an SO-
permeation tube set up as shown in Figure A2 and A3 of the Appendix, page
116.  Reference samples should span a range from 0.20 to 1.0 absorbance
units.  The specific values should be varied from audit to audit.
          fan. peJifioiming cnecfe - The operator routinely measures  1  control
sample, that he has prepared, for every set of determinations as  a  check on
the continued reliability of the calibration curve.  The measurement of
independent reference samples evaluates the overall analysis procedure
including operator, chemicals, and technique.

Reference samples should be dispersed randomly throughout the samples
awaiting analysis at the rate of 7 reference samples per 100 field  samples.
This auditing level can be followed as long as a total of 100 samples will
be analyzed per quarter.  If possible the reference samples should  not be
recognizable to the analyst as a reference sample.

TVieotmeitt oft daJta. - Obtain from the person that performed the audit (see
page 44) the measured, (yg SO-) , and check on known value, (yg SO.)
and compute the difference     m                                    c
                     d   =  (yg SO )   -  (yg SO,)
                      2J         2 cj         2 mj


where j is the j   time that the check has been made during a given
           auditing period.
                                    63

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Data Processing Check - Independent checks on data processing errors are
made as directed in the Operations Manual, page 52.
                         check - A data processing check should be made
on 7 out of 100 samples.  The check should be made by an individual other
than the operator who performed the original calculations.  The check
should begin with the raw data through the point of recording the
concentration on the SAROAD form.

Tn&Ltmwt. 0£ data. - Compute the percent difference between the check
                3                                     3
value, (yg SO./m ) , and the original value, (yg S0,/m ) , by
             '    c                                z    o


                       (yg S02/m3)  - (yg S02/m3)

                 d,  = - - - r - — * 100
                   J          (yg S0,/m3)
where   j is the jfc  time that the check has been made during a
             given auditing period.

Treatment of Collected Information

Identification of Defects - One procedure for identifying defects is to
evaluate auditing checks in pairs; i.e., d..., d.., d . d  ., d . d «, ....,
d._ d-_.  If one or both members of the pair are defective, it counts as
one defect.  No more than one defect is declared per set.  Data processing
errors should be corrected when found, and are not, therefore discussed
here.

Any set of auditing checks in which the value of d. . or A^. is greater

than +9 or + 1.2 yg S02 respectively, will be considered a defect.
These values are assumed to be the 30 values and are discussed in the
subsection on Suggested Standards for Judging Performance on page 66.
As field data become available, these limits should be reevaluated and
adjusted, if necessary.

Reporting Data Quality - Each lot or quarter of data submitted with SAROAD
forms or tapes should be accompanied by the minimum data qualifying
information as shown in Figure 16.  The individual responsible for the
quality assurance program should sign and date the form.  As an illustra-
tion, values from the subsection on Suggested Standards for Judging
Performance, page 66, are used to fill in the blanks in Figure 16.  The
reported auditing rate is the rate in effect at the beginning of the
auditing period.  An increase or decrease in auditing rate during the
auditing period will be reflected by the total number of checks reported.
The reason for change should be noted on the form.

-------
Supervisor's Signature_
           Reporting Date
Auditing Rate for Data Errors:  n - 7, N - 100
Definition of Defect:  |dj, |> 9,
                              1.2
                   and |d3Ji 3
Number of Defects Reported_
(should be circled in the  table below)
Audit
1. Volume/Flow-Rate Check
2. Measurement of Reference
Samples (d2.)
3. Data Processing Check
Cd3j>
Check Values
dll
d21
d31
d12
d22
dd32
d13
d23
d33
_ 	
	 _

Q
In
d2n
d3n
 Data processing errors are corrected when found at the ± 3 percent
 level and are therefore, not reported as defects.
                  Figure 16:  Data Qualification Form
                                    65

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Check values  (i.e., d's, d- 's and d,,'s) are calculated as directed on

pages 62 and  63 and reported in Figure  16.  Values of d,  need be reported

only if requested by the manager.  All  reported check values exceeding the
definition of a defect should be marked for easy recognition by circling
on the form.  In case of a defect from  the measurement of reference samples
(d. ) report  the defective measurement  as well as the measurement made

after the trouble  is  corrected.  Both  values would be in the same column
of Figure 16  (i.e., two values of one d,,. would be reported) with the

defect circled.  The other value will be used in evaluating data quality as
described in  the Management Manual, page 96.

SUGGESTED STANDARDS FOR JUDGING PERFORMANCE USING AUDIT DATA

Results from  a collaborative test of the pararosaniline method (Ref. 6)
show that precision is a function of the SO- concentration.  The

performance standard given below in Table 2 for measurement of reference
samples represents the 3o value from that test.  This standard should be
reevaluated and adjusted as field data become available.

The suggested standard for comparing the volume/flow-rate values is no
more than a rough estimate.  There is the error associated with the
initial and final calibration of the critical orifice and the accuracy
of the wet test meter.  Under field conditions a standard deviation of
+ 3 percent of the actual value seems reasonable.  Again this standard
should be reevaluated as field data become available.
COLLECTION OF INFORMATION TO DETECT AND/OR IDENTIFY TROUBLE

In a quality assurance program one of the most effective means of
preventing trouble is to respond immediately to reports from the operator
of suspicious data  or equipment malfunctions.  Application of proper
corrective actions at this point can reduce or prevent the collection of
poor quality data.  Important error sources, methods for monitoring
variables, and suggested control limits for each source are discussed in
this section.

Identification of Important Parameters

Measurement of sulfur dioxide in the ambient atmosphere by the manual
pararosaniline method requires a sequence of operations and events that
yield as an end result a number that serves to represent the average mass
of sulfur dioxide per unit volume of air over the sampling period.

The measurement process can be roughly divided into three phases.  They
are:  1) sample collection, 2) sample analysis, and 3) data processing.
                                    66

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               Table 2.  SUGGESTED PERFORMANCE STANDARDS
Standards for Defining Defects
u
1.  Volume/Flow-Rate Check; |d..|  > 9

2.  Measurement of Reference Samples; IcU-J - 1-2 Ug S02

Standard for Correcting Data Processing Errors

3.  Data Processing Check; Jdj.| > 3

Standards for Audit Rates

4.  Suggested minimum auditing rates for data error;
    number of audits, n - 7; lot size, N - 100; allowable number of
    defects per lot, d - 0.

Standards for Operation

5.  If at any time d - 1 is observed (i.e., a defect is observed) for
    either .d.. or d,., increase the audit rate to n - 20, N - 100 until
    the cause has been determined and corrected.

6.  If at any tine d - 2 is observed (i.e., two defects are observed In
    the same auditing period), stop collecting data until the cause has
    been determined and corrected.  When data collection resumes, use
    an auditing level of n - 20, N - 100 until no defects are observed
    in three successive audits.

7.  If at any time either one of the two conditions listed below is
    observed, 1) Increase the audit rate to n - 20, N • 100 for the
    remainder of the auditing period, 2) perform special checks to
    identify the trouble area, and 3) take necessary corrective action
    to reduce error levels.  The two conditions are:

         (a)  two (2) d.. values exceeding ± 6, or

               four (4) d, . values exceeding ± 3.

         (b)  two (2) d»  values exceeding ± 0.8 yg SO-, or

               four (4) d2. values exceeding ± 0.4 yg S02.
                                     67

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Sample Collection - The sample collection phase of the measurement method
contains numerous sources of error.  Some errors can be eliminated by a
conscientious operator, while others are inherent and can only be
controlled.  The sources of error are:

      (1)  flow- rate calibration,

      (2)  determination of the volume of air sampled,

      (3)  elapsed time between sample collection and analysis,

      (4)  exposure of sample to direct sunlight, and

      (5)  entrainment or loss of sample other than by evaporation.
                      - Flow rates for critical orifices calibrated against
a wet test meter at different times, by different individuals, but with the
same equipment showed a standard deviation of less than 2 percent of the
mean (Ref. 1).  When a large population of laboratories is considered, the
variability would undoubtedly increase significantly.  Rotameter calibra-
tions would not be expected to be any more precise than critical orifice
calibrations.  Large flow-rate calibrations will be detected by the volume/
flow-rate check as part of the auditing procedure.  However, to maintain
the error at or near a minimum the wet test meter or calibrated rotameter
used for calibration should be checked against a high quality soap-bubble
meter at least once a quarter.
               $ the. votume. 0$ CUM. &cunpte.d - The volume of air sampled is
estimated from the calibration of the critical orifice before and after
sampling (flow-rate readings before and after sampling if a rotameter is
used) and the sampling period time.  Such estimate assumes that any change
in flow rate during the sampling period is linear with time.  Nonlinear
changes due to such things as temporary plugging of the line or critical
orifice from condensed moisture are not detected by this method.  Also,
a system leak between the absorber and the critical orifice would introduce
an error in the calculated volume unless detected and corrected by the
operator prior to sample collection.

Errors in the calculated volume are checked as part of the auditing process
by using a wet test meter on-site to measure the integrated volume.  A
discrepancy in the integrated volume measured by the wet test meter and the
volume calculated in the usual manner implies that there could be:

     (1)  system leaks,

     (2)   non-linear changes in flow-rate,

     (3)  an error in the timer, or

     (4)  flow-rate calibration error.

Each item should be checked and verified.


                                    68

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For the 24-hour sampling period where a calibrated rotameter is used to
read the flow rate before, during, and after the sampling period, only
items (1) and (4) above can be detected.  There is only a small possibility
of detecting a temporary change in flow rate (item 2) .  The tinier should be
checked independently against an elapsed time indicator at least every six
months.

An additional source of error in estimating the sample volume is due to
the inability to determine an average temperature- for the sampling period.
This is more important for 24-hour samples than it is for the shorter
periods.  A method for estimating the average temperature is suggested
in the Operations Manual, page 34.

Elapsed time between sample collection and analysis - It has been shown that
exposure of the sample to temperatures above about 5°C results in SO^ losses.

A loss of about 1.8 percent per day occurred at 25°C and no losses were
observed at 5°C (Ref. 2).

It is obvious that long delays between sample collection and analysis at
unrefrigerated or uncontrolled conditions will result in sizeable errors.

Every means should be employed to minimize the time that a sample is
exposed to temperatures above 5°C.
           jJ Aoumpti to ctiJie.c£ Aan^igkt -  Exposure  of  the  sample  to  direct
sunlight during  or after collection  can  result  in deteoriation  of  the
sample.  Losses  from 4  to  5  percent  were experienced by  samples exposed
to bright  sunlight for  30  minutes  (Ref.  2).   Therefore,  it  is recommended
that the bubbler be wrapped  in  tin foil  anytime it is  exposed to the direct
sunlight for more than  1 or  2 minutes that might  occur in the normal
transfer of 24-hour samples  from  the sampling train box  to  the  shipping
block.

EwtSULLm
-------
Sample Analysis - To realize a high level of precision and accuracy from
the analysis phase of the method the analyses must be done carefully, with
close attention to temperature, pH of final solution, purity of the
chemicals and water, and standardization of the sulfite solution (Ref. 2).

Important parameters in the analysis phase include:

     (1)  purity of the chemicals and water,

     (2)  spectrophotometer calibration,

     (3)  pH of the solution being analyzed, and

     (4)  temperature at analysis compared to temperature
          at calibration.

Pu/l^Cj/  OfJ dnJUMJ^]JLt> ami WcuteA - Purity  of  the chemicals and water  is
extremely important in  obtaining reproducible results because of the  high
sensitivity of  the method.  As recommended in the  Operations Manual the
purity of the pararosaniline  dye is  checked and, if necessary, purified and
assayed before use.  The water used  must be free of oxidants and should be
double-distilled when preparing and  protected from the atmosphere  when
stored and transferred  from container to container.  All other chemicals
should be ACS grade and special care exercised not to contaminate  the
chemicals while in storage .or when removing portions for reagent
preparation.
                  ca&i.faAa£ton - The spectrophotometer should be adjusted
for 100 percent transmittance when measuring a sample cell of pure water
prior to each set of determinations.  Also, the calibration of the wave-
length scale and the transmittance scale should be checked periodically or
any time reference samples cannot be measured within prescribed limits after
checks of the reagents and water have failed to identify the trouble.

The calibration of the wavelength scale can be checked by plotting the
absorption spectrum (in the visible range) of a didymium glass which has
been calibrated by the National Bureau of Standards.

The transmittance scale can be checked using a set of filters from the
National Bureau of Standards.
pH 0& the. -&o£o£uw bexjtg anatyzzd - For this method the maximum sensitivity
occurs when the pH of the final solution is in the region 1.6 + 0.1  (Ref. 2)
If care is exercised in reagent preparation and the analysis phase the pH
should always be within the above limits.  Phosphoric acid provides  the pH
control; hence, it should be checked first when the pH is detected outside
the above range.
                                    70

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            - Temperature affects the rate of color formation and fading
of the final color.  Also, the reagent blank has a very high temperature
coefficient.  Therefore, it is important that the temperature at analysis
be within + 2°C of the temperature at which the calibration curve was
developed.  If the normal room temperature varies more than + 2°C from a
set value it is recommended that a constant-temperature bath be used if
a high degree of accuracy is desired.

Large variations in temperature would be detected as error in measuring
control samples and/or reference samples.

Data Processing - Data processing, starting with the raw data through the
act of recording the measured concentration on the SAROAD form, is subject
to many types or errors.  The approach used in the Operations Manual,
page 52  means that one can be about 55 percent confident that no more
than 10 percent of the reported concentrations are in error by more than
+ 3 percent.


The magnitude  of  data  processing errors  can be estimated  from,  and
controlled  by,  the auditing program through performance of periodic checks
and making  corrections when large errors  are  detected.  A procedure for
estimating  the  bias  and  standard deviation of data processing  errors  is
given  in  the Management  Manual,  page 98.

How to Monitor  Important Parameters

Table  3 lists sbme of  the parameters that need to be monitored  when using
the manual  pararosaniline method for measuring atmospheric SO-.   Excess
error  attributable to  one or more of variables 1, 2, 6, 7, 8,  and 9 will
be detected by  the auditing program.   Variable 3, elapsed time  between
sample collection  and  analysis  is determined  for each  sample as part  of
the normal  operating procedures.   Variables  3 and 4  involve an  operation or
subjective  decision  by  the field operator.  They can only be monitored by
observing the operator  on-site.   This can be  carried out  in conjunction
with  the  performance of  the volume/flow-rate  audit.

Suggested Control  Limits

Appropriate control  limits for  individual variables will  depend on the
level  of  performance needed.  Table 4 gives  suggested  performance
standards for measuring  reference samples and for volume/flow-rate checks.

Standards given for  the  measurement or determination of the sampled volume
or of  the average  flow  rate for the sampling  period  are merely  estimates.
They are  not based on  actual data.   The error involved  in making this
determination has  been divided  into five components.   They are:  1)  errors
in calibrating  the rotameter or critical orifice, 2) system leaks between
the bubbler and flowmeter, 3) intermittent plugging  of  lines or critical
orifice,  loss of  power,  etc., 4)  error in determining  the average
temperature during the  sampling site,  and 5)  the error  in determining the
average pressure  during  the sampling period.


                                     71

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                Table 3.  METHODS OF MONITORING VARIABLES
             Variable
      Method of Monitoring
 1.  Flow-rate calibration
 2.  Volume of air sampled

 3.  Elapsed time between sample
     collection and analysis
 4.  Exposure of sample to direct
     sunlight

 5.  Entrainment or loss of sample
     other than by evaporation

 6.  Purity of chemicals and water
 7.  Spectrophotometer calibration
 8.  pH of final solution
 9.  Temperature
10.  Data processing errors
Measurement of volume/flow rate as
part of the auditing process.

Same as (1) above.

Dates of collection and analysis are
taken from the Sample Record Sheet
and Operational Data Log Book,
respectively, for every sample.

Observe operator technique on-site.
Observe operator technique on-site.
Purity of pararosaniline and water
are checked as part of the oper-
ating procedure.  Other chemicals
are purchased as ACS grade.

Spectrophotometer calibration is
checked with calibrated filters and/
or didymium glass when a reference
sample cannot be measured within
limits.

Measure the pH of the final
solution of 1 sample from each site
when first starting a quality
assurance program and once a month
afterwards.

Temperature should be monitored with
a wall thermometer, or if a constant
temperature bath is used, a ther-
mometer immersed in the bath.

Data processing checks are performed
as a part of the auditing program.
                                     72

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                  Table 4:  SUGGESTED CONTROL LIMITS FOR PARAMETERS AND/OR VARIABLES
Parameter /Variables
1. Determination of volume/average flow rate
a) Calibration error
b) System leaks between bubbler or flowmeter
c) Intermittent plugging of lines
d) Error in average temperature of
sampling period
e) Error in average pressure of sampling
period
Total:
i
d,=d + d, + d + d, + d
1 a D c d e
V 2 2 2 2 2
a + a, -fa + a, + a
abode
2. Measurement of reference samples
Suggest
Mean
dj_ = -0.04(X)*
da = o
dfe = -0.02(X)
d = -0.02(X)
c
dd = 0
de = o

dj = -0.04(X)
d2 = 0
ed Performance S
Standard
Deviation
o^ = 0.025(X)
a = 0.02(X)
a, = 0.007(X)
b
a = 0.007(X)
c
a. = 0.01(X)
d
a = 0.006(X)
e

a^ = 0.025(X)
a2 = 0.4 yg S02
andards
Upper Limit
(+3o)
-0.10(X), +0.06(X)







+1.2 yg S02
*-
 X = mean or average value.

-------
System leaks and Intermittent plugging of lines or loss of electrical power
would result in a calculated volume of air larger than the volume actually
sampled.  This in turn would negatively bias the measured concentration.
Therefore, d^ and d  of Table 4 are shown as negative biases.  The other
errors are assumed to be normally distributed about a mean value of zero.
More accurate estimates of these variables can be made as data from the
quality assurance program becomes available.

Combining the means and standard deviations of component errors as


                     d  = d  +d+d  + d. + d
                      1    a   T>    c    d    e
and
                        •A/a2 + a2 + a2 + a2 + a2
shows that at this level of control the suggested performance standard
for measuring the volume /flow-rate is satisfied as  is evidenced by
and

                                a  " °
                                      r
The suggested standard for the measurement of  reference  samples  is  the value
obtained in a collaborative test of  the method (Ref.  6).

PROCEDURES FOR IMPROVING DATA QUALITY

Quality control procedures designed  to control or adjust  data  quality may
involve a change in equipment or in  operating  procedures.  Table 5  lists
some possible procedures for improving data quality.  The applicability
or necessity of a procedure for a given monitoring  situation will have to
be determined from results of the auditing process  or special  checks
performed to identify the important  variables.  The expected results are
given for each procedure in qualitative terms.  If  quantitative  data are
available or reasonably good estimates can be  made  of the expected  change
in data quality resulting from implementation  of each procedure, a  graph
similar to that in Figure 22, page 105 of the  Management Manual  can be
constructed.  The values used in Table 13 and  Figure  22  are assumed and
were not derived from actual data.

For making cost estimates, a reference system  consisting of a  sampler
equipped with a rotameter and the routine performance of those control
checks spelled out in the Operations Manual is assumed.
                                    74

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                            Table 5.   QUALITY CONTROL PROCEDURES OR ACTIONS
Procedure/Action
AO Reference Conditions
Al Correct for
Temperature


A2 Minimize sample
shipping and
storage time

A3 Temperature
control
A4 Personnel
training

Description of
Action
System using routine
procedure as given in
the Operations Manual
For 24-hour samples
obtain from weather
station or make on-
site measurement of
temper atu re . Es t imat e
an average value for
the period and correct
sampled volume to
298°K.
Minimize time between
sample collection and
analysis by mailing
sample immediately
after collection, use
special mailing, and
analyze as soon after
reaching the labora-
tory.
Use a constant-temper-
ature bath for cali-
bration and analysis.
Hold a 1-week work
shop for operators
from all phases of
the measurement
process once a year.
Expected Results
bias (T) =-0.04(X)*
OT =(41)[0.7+0.001(X)]
Reduces error in
calculated sample volume.


Reduce the error due the
loss of SC>2 with time
before analysis.

Reduce variability in the
analytical phase due to
temperature fluctuations .
Reduce operational errors
through increased aware-
ness of the pitfalls and
increased interest in
doing a good job.
Costs
Equip ."""
	
15


100

250
none

Personnel
	
none


100

10
200

Total
	
15


200

260
200

*_
 X = true concentration of SO
                             2'

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Equipment, manpower requirements, and the continuing cost of labor and
supplies are estimated for each procedure.  For these estimates technician
time was valued at $5 per hour and engineering time at $10 per hour.  Equip-
ment life was taken as 5 years.  All calculations were based on a sample lot
of 100 and an average sampling rate of 60 samples per year per sampling site.

A procedure for selecting the appropriate quality control procedure to
insure a desired level of data quality is given below:

     (1)  Specify the desired performance standard, that is,
          specify the limits within which you want the deviation
          between the measured and the true concentration to
          fall a desired percentage of the time.  For example,
          to measure within + 12 percent of the true value,
          95 percent of the time, the following performance
          standards must be satisfied:


                     I* ± 2STI 1 °-12 x V8 S02/m3.

     (2)  Determine the system's present performance level  from
          the auditing process, as described on page 101 of the
          Management Manual, by setting
          and

                          a
                           T
          If the relationship of (1) above is satisfied, no
          control procedures are required.

     (3)  If the desired performance standard is not satisfied,
          identify the major error components by performing
          special checks.

     (4)  Select the quality control procedure(s) which will
          give the desired improvement in data quality at the
          lowest cost. .Figure 22 on page 105 of the Management
          Manual illustrates a method for accomplishing this.

The relative position of actions on the graph in Figure 22 will differ for
different monitoring networks according to type of equipment being used,
available personnel, and local costs.  Therefore, each network would need
to develop its own graph to aid in selecting the control procedure
providing the desired data quality at the lowest cost.
                                    76

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PROCEDURES FOR CHANGING THE AUDITING LEVEL TO GIVE THE DESIRED LEVEL OF
CONFIDENCE IN THE REPORTED DATA

The auditing process does not in itself change the quality of the reported
data.  It does provide a means of assessing the data quality.  An Increased
auditing level increases the confidence in the assessment.  It also increases
the overall cost of data collection.

Various auditing schemes and levels are discussed on page 82 of the
Management Manual.  Numerous parameters must be known or assumed in order
to.arrive at an optimum auditing level.  Therefore, only two decision
rules with two levels of auditing each will be discussed here.

For conditions as assumed on page 82 of the Management Manual, a study of
Figure 20, page 95, gives the following results.  These conditions may or
may not apply to your operation.  They are included here to call attention
to a methodology.  Local costs must be used for conditions to apply to
your operation.

Decision  Rule  -  Accept  the  Lot  as Good If No Defects^ Are  Found
(i.e.,_d  - 0).

Most Cost Effective Auditing Level  -  In Figure  20  the  two solid lines  are
applicable to  this decision rule, i.e., d = 0.  The  cost  curve has  a
minimum at n = 7 or an  auditing level  of 7 checks  out  of  100  sampling
periods.  From the probability  curve  it is seen that at this  auditing
level  there is a probability of 0.47  of accepting  a  lot as  good when the
lot  (for  N = 100) actually  has  10 defects.  The associated  average  cost
is 240 dollars per lot.

Auditing  Level for Low  Probability  of  Accepting Bad  Data  -  Increasing  the
auditing  level to n = 20, using the same curve  in  Figure  20 as above,
shows  a probability of  0.09 of  accepting a lot  as  good when the lot
actually  has 10  defects.  The average  cost associated  with  this level  of
auditing  is approximately 425 dollars  per lot.

Decision  Rule  -  Accept  the  Lot  as Good If No  More^ Than One (1) Defect
Is Found  (i.e.,  d <. 1).

Most Cost Effective Auditing Level  -  From the  two  dashed  curves in
Figure 20 it can be seen that the cost curve has a minimum  at n = 14.  At
this level of  auditing  there is a probability  of 0.55  of  accepting  a lot
of data as good  when it has 10  defects.  The average cost per lot is
approximately  340 dollars.

Auditing  Level for_Low  Probability  of  Accepting Bad  Data  -  For an auditing
level  of  n = 20  the probability of  accepting a  lot with 10  percent  defects
is about  0.36  as read from  the  d _<  1  probability curve.   The average cost
per  lot is approximately 375 dollars.

It must be realized that the shape  of  a cost curve is  determined  by the
assumed costs  of performing the audit  and of reporting bad  data.   These
costs  must be  determined for individual monitoring situations in  order
to select optimum auditing  levels.
                                   77

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MONITORING STRATEGIES AND COST

Selecting the optimum monitoring strategy in terms of cost and data quality
requires a knowledge of the present data quality, major error components,
cost of implementing available control procedures, and potential increase
in system precision and accuracy.

A methodology for comparing strategies to obtain the desired precision of
the data is illustrated in the Management Manual, page 103, Table 5,
page 75 lists control procedures with estimated costs of implementation
and expected results in terms of which error component (s) are affected by
the control.  Numerical values of the expected results as given in Table 13,
page 106, are estimates and were not derived from actual data.

Three system configurations identified as best strategies in Figure 22,
page 105, of the Management Manual are summarized below.

Again, local costs and expected results derived from field data are
required to select optimum strategies by this method.

Reference Method (AO)

Description of Method - This refers to a typical sampling operation as
described in the Federal Register.  Routine operating procedures as given
in the Operations Manual are to be followed with special checks performed
to identify problem areas when performance standards are not being met.
Corrections for delay between collection and analysis and for average
temperature are not made.  An auditing level of n=7, N=100 is to be carried
out for  this strategy.  This method or strategy is identified as AO in
Table 13 and Figure 22 in  the  Management Manual.

Costs - Taken as reference or zero cost.

Data Quality - Data quality can be described by


                 (yg S09/m3)  = (yg SO /m3)  - ? + 3o  -
                       £    rv         £    m         1
where   (yg S0«/m )  = true average concentration of sulfur
                   T   dioxide, and
                 o
        (yg S0_/m )  = measured average concentration of
                   m   sulfur dioxide.
                                     78

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Taking the hypothesized values of the bias and standard deviation from
Table 13 and using in the above relationship shows that for a true
                        3                   o
concentration, (yg S02/m )  , of 380 yg S02/m , the measured value,

(yg S09/m ) , would fall within the following limits
      *    m


                       308  < (yg S0,/m3)  < 422
                                   L    m

approximately 99.7 percent  of the time.

Modified Reference Method (A5)

Description of Method^ - This strategy is identical to the reference
method above except that corrections are made for the average temperature
for the sampling period (Al) and special personnel training in the form
of a yearly workshop.


Costs - The average cost per 100 samples is estimated at 215 dollars above
the cost of the reference method (see Figure 22, page 105).
Data Quality - From Table 13, values of bias and standard deviation are
seen to be T = -0.03 percent and ST = C """       '  -'  " -  ---  - -------

The data quality would be described by
      (yg SO,/m3)T =  (yg S0,/m3)  +  (0.03 4- 3 * 0.035)(yg S0,/m3)  .
            *    1         L    m         ~                  '    T


For a true concentration 380  yg S0»/m  the measured value would  fall
within the limits


                       328 <  (yg S00/m3)  < 409
                                   L    m
approximately 99.7 percent of the time.

Modified Reference Method Plus Action A2  (A7  =  Al + A2 + A4)

Description of Method - This method is identified as A7  in Figure  22 of
the Management Manual.  This method is the same as the modified  reference
method above with the addition of Action A2 which would  reduce errors due
to loss of SO. by minimizing time between collection and analysis.
                                    79

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Costs - Average cost per lot is estimated at 415 dollars above the cost
of the reference method.

Data Quality - From Table 13 the data quality would be described by
      (yg S0,/m3)  = (yg S07/m3)  + (0.01 + 0.03 ) (yg S0,/m3)  .
            2    T         l    m         ~~             L    T

                                        a
For a true concentration of 380 yg S0_/m  the measured value would fall
within the limits
                       336 < (yg S07/m3)  < 416  .
                                        m
Results from these estimated values show that in going from Method AO to
Method A7, the data spread is decreased by about 24 percent and the range
is more evenly distributed about the true concentration value.
                                    80

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SECTION IV                  MANAGEMENT MANUAL
GENERAL

The objectives of a data quality assurance program for the Pararosaniline
Method of measuring the concentration of S0_ in the ambient air were given

in Section I.  In this part of the document, procedures will be given to
assist the manager in making decisions pertaining to data quality based on
the checking and auditing procedures described in Sections II and III.
These procedures can be employed to:

     (1)  determine the extent of independent auditing to be
          performed,

     (2)  detect when the data quality is inadequate,

     (3)  assess overall data quality,

     (4)  relate costs of data quality assurance procedures
          to a measure of data quality, and to

     (5)  select from the options available to the manager
          the alternative(s) which will enable him to meet
          the data quality coals by the most cost-effective
          means.

The determination of the extent of auditing is considered in the subsection
entitled "Auditing Schemes."  Objectives 2 and 3 are discussed in the
subsection entitled "Data Quality Assessment," page 96.  Finally,
Objectives 4 and 5 above are described in the subsection entitled "Data
Quality Vs. Cost of Implementing Actions," page 103. The cost data are
assumed and a methodology provided.  When better cost data become
available, improvements can be made in the management decisions.

If the current reference system is providing data quality consistent with
that required by the user, there will be no need to alter the physical
system or to increase the auditing level.  In fact several detailed
procedures could be bypassed if continuing satisfactory data quality is
implied by the audit.  However, if the data quality is not adequate, e.g.,
either a large bias and/or imprecision exists in the reported data, then
(1) increased auditing should be employed, (2) the assignable cause
determined, and (3) the system deficiency corrected.  The correction can
take the form of a. change in the operating procedure, e.g., minimize
delay between collection and analysis of sample by special mailing; or
it may be a change in equipment such as the installation of an improved
temperature control system.  An increase in the auditing level will
increase the confidence in the reported measure of precision/bias and aid
in identifying the assignable cause(s) of t.he large deviations.  The level
of auditing will be considered in the next subsection.
                                    81

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The audit procedure and the reported results can serve a two-fold purpose.
They can be used to (1) screen the data, by lots of say N = 50 or 100, to
detect when the data quality may be Inadequate, and (2) calculate the bias
and precision of the audited measurement and hence estimate the bias/
precision of the final reported concentration of SO. In the ambient air.

In order to perform (1), suggested standards are provided for use In
comparing the audited results with the reported values and a defect Is
defined In terms of the standards.  This approach requires only the
reporting of the number of defects In the n auditing checks.  In the second
method above, It Is required to report the measures of bias/precision in
the audits.  These values are then used in assessing the overall data
quality.  Approach (1) is suggested as a beginning step even though it will
not make maximum use of the data collected in the auditing program.  The
simplicity of the approach and the explicit definition of a defect will
aid in its implementation.  After experience has been gained in using the
auditing scheme and in reporting and calculating the results, it is
recommended that approach (2) be implemented.

It is Important that the audit procedure be independent of previously
reported results and be a true check of the system under normal operating
procedures.  Independence can be achieved, for example, by providing a
control sample of unknown concentration of SO- to the operator and

requesting that he measure and report the concentration of the sample.
To Insure that the check is made under normal operating procedures, it
is required that the audit be performed without any special check of the
system prior to the audit other than that usually performed during each
sampling period.

AUDITING SCHEMES            '

Auditing a measurement process costs time and money.  On the other hand,
reporting poor quality data can also be very costly.  For example, the
reported data might be used to determine a relationship between health
damage and concentrations of certain pollutants.  If poor quality data are
reported, it is possible that invalid inferences or standards derived from
the data will cost many dollars.  These implications may be unknown to the
manager until some report is provided to him referencing his data; hence,
the importance of reporting the precision and bias with the data.

Considering the cost of reporting poor quality data, it is desirable to
perform the necessary audits to assess the data quality and to invalidate
unsatisfactory data with high probability.  On the other hand, if the data
quality is satisfactory, an auditing scheme will only increase the data
measurement and processing cost.  An appropriate tradeoff or balance of
these costs must be sought.   These costs are discussed under Cost
Relationships.
                                    82

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Now consider the implication of an auditing scheme to determine or judge
the quality of the reported data in terms of an acceptance sampling
scheme.  Let the data be assembled into homogeneous lots of N = 50 or
100 sampling periods.  Suppose that n periods are sampled in the manner
suggested in Section III.  That is, the N = 50 or 100 sampling periods are
subdivided into equal time intervals (as nearly equal as possible); then
one day is selected at random during each interval.  Figure 17 gives a
diagram of the data flow, sampling, and decision making process for an
auditing level of n = 7.

Statistics of Various Auditing Schemes

Suppose that the lot size is N = 100 periods (days), that n = 7 periods
are selected at random, and that there are 5% defectives in the 100, or
5 defectives.  The probability that the sample of 7 contains 0, 1, ..., 5
defectives is given by the following.
                   p(0 defectives) =
                                       10
                                      ( 7 )
and for d defectives
                   p(d defectives) = x"'v' " , d < 5.

                                      \ 7 )
The values are tabulated below for d = 0, 1, ..., 6 and for the two data
quality levels.

                       Table 6.  P(d defectives)

                                      Data Quality

                            D=5% Defectives	D=15% Defectives
0
1
2
3
4
5
6

*(5\ (95\ 5! 95!
\0/ V 7/ 0'5' 7!88!
/100\ / 100! V
\ 7 ) \,7!93! )
0.6903
0.2715
0.0362
0.0020
0.00004
« 0
= 0
95. 94. ..89
100'99-"94
a?
0.3083
0.4098
0.2152
0.0576
0.0084
0.0007
«0
= 0.6903.

-------
Data Flow
Lot 1
H - 100
Day*


Lot 2
N » 100
Days


                                             Sample
                                             n - 7
                                         Periods  (days)
       Observe
    d • 0 defect*
   Observe
d - 1 defect
                           Calculate Costs of
                             Accepting and
                           Rejecting the Lot
    Accept Data If
 1. Cost Comparison
    Favors This Action
 2. Data Quality Is
    Acceptable
                       Reject  Data
                        Otherwise
       Figure 17:  Data Flow Diagram for Auditing Scheme
                                 84

-------
M

0)

4J
CO


t
u
01

-------
                                                    :   d <; 1,  D - 6X
         --   d • 0, D - 20Z
                                10           15
                                 Sample  Size (n)
   Figure  18B:  Probability of d Defectives  in the  Sample If the

               Lot  (N • 50) Contains DZ Defectives.
This graph is for a lot sice of N « 50.  Only whole numbers of defectives
are physically possible; therefore, even values of D  (i.e., 6, 10, and
20 percent) are given rather than the odd values of 5 and 15 percent as
given in Figure ISA.
                                      86

-------
 Figure  18A gives  the  probabilities  of  d = 0 and d  <_ 1 defectives as a
 function  of sample  size.   The  probability is  given for  lot  size N = 100,
 D ™  5 and 15%  defectives,  for  sample sizes  (auditing levels)  from 1 to 25.
 For  example, if n = 10 measurements are audited and D = 5%  defectives,
 the  probability of  d  = 0 defectives is 0.58.  Figure 18B gives the proba-
 bilities  for lot  size N =  50,  for D =  6, 10,  and 20% defectives, and for
 d =  0 and d £  1.  These curves will be used in calculating  the cost
 relationships.

 Selecting the  Auditing Level

 One  consideration in  determining an auditing  level n used in  assessing
 the  data  quality  is to calculate the value of n which for a prescribed
 level of  confidence will imply that the percent of defectives in the
 lot  is  less than  10 percent, say, if zero defectives are observed in the
 sample.*   Figures 19A and  19B  give  the percentage  of good measurements
 in the  lot sampled  for several levels  of confidence, 50, 60,  80, 90, and
 95%.  The curves  in Figure 19A assume  that 0  defectives are observed in
 the  sample, and those in Figure 19B that 1 defective is observed in the
 sample.   The solid  curves  on the figures are  based on a lot size of N = 100;
 two  dashed curves are shown in Figure  19A for N =  50; the differences
 between the corresponding  curves are small for the range of sample sizes
 considered.
                               \
 For  example, for  zero defectives in a  sample  of 7  from  a lot  of N = 100,
 one  is  50% confident  that  there are less than 10%  defective measurements
 among the 100  reported values.  For zero defectives in  a sample of 15
 from N  =  100,  one is  80% confident  that there are  less  than 10% defective
'measurements.  Several such values  were obtained from Figure  19A and
 placed  in Table 7 below for convenient reference.
              Table  7.  REQUIRED AUDITING LEVELS n FOR LOT
                 SIZE N = 100 ASSUMING ZERO DEFECTIVES

      Confidence Level            D = 10%             15%           20%
50%
60%
80%
90%
95%
7
9
15
20
»25
<5
6
10
15
18
<5
<5
8
11
13
 Obviously,  the definition of defective need not  always be  the  same and
must be learly stated each time.  The definitions employed  herein  are
based on results given  in the collaborative test  report  (Ref. 6).
                                     87

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                                                       N - 100
                                                  	N - 50
                             10          15
                              Sample Size (n)
Figure 19A:  Percentage of Good Measurements Vs. Sample Size
      for No Defectives and Indicated Confidence Level
                                   88

-------
                            L© Sis© (n)
19B:
                             89

-------
Cost Relationships

The auditing scheme can be translated into costs using the costs of
auditing, rejecting good data, and accepting poor quality data.  These
costs may be very different in different geographic locations.  There-
fore, purely for purposes of illustrating a method, the cost of auditing
is assumed to be directly proportional to the auditing level;  For n • 7
it is assumed to be $155 per lot of 100.  The cost of rejecting good
quality data is assumed to be $600 for a lot of N - 100.  The cost of
reporting poor quality data is taken to be $800.  To repeat, these costs
given in Table 8 are assumed for the purpose of illustrating a methodology
of relating auditing costs to data quality.  Meaningful results can only
be obtained- by using correct local information.

     	  Table 8.  COSTS VS. DATA QUALITY               	
                                           Data Quality
     Reject Lot of
     Data
                                "Good"
                                    "Bad"
                                D ^ 10%
                           Incorrect Decision
                                   D > 10%
                               Correct Decision
Lose cost of performing     Lose cost of performing
audit plus cost of reject-  audit, save cost of not
ing good quality data.      permitting poor quality
(-$600 - $155)              data to be reported.
                            ($400 - $155)
     Accept Lot of
     Data
     Correct Decision

Lose cost of performing
audit.
(-$155)
  Incorrect Decision

Lose cost of performing
audit plus cost of de-
claring poor quality
data valid.
(-$800 - $155)
Suppose that 50 percent of  the  lots have more  than  10  percent  defectives
and 50 percent have less than 10 percent defectives.   (The  percentage  of
defective lots can be varied as will be described in the  final report
under the contract.)  For simplicity of calculation, it is  further  assumed
that the good lots have exactly 5 percent defectives and  the poor quality
lots have 15 percent defectives.
 Cost of performing  audit  varies with the sample size;  it is assumed to
be  $155 for n -  7  audits per  N - 100 lot  size.
                                     90

-------
Suppose that n - 7 aeasurements out of a lot of N «• 100 have been audited
and none found to be defective.  Furthermore, consider the two possible
decisions of rejecting the lot and accepting the lot and the relative
costs of each.  These results are given in Tables 9A and 9B.
Table 9A.   COSTS IF 0 DEFECTIVES ARE OBSERVED AND THE LOT IS REJECTED

Reject Lot

D - 5Z
D - 15%
Correct
Decision
	
P2 • 0.31
C2 =400 - 155
Incorrect
Decision
Px = 0.69
Cj^ = -600 - 155
	
Net Value ($)
p^ - -$521
P2C2 = $76
Cost
                                                       + p2C2--$445
Table  9R.   COSTS IF 0 DEFECTIVES ARE OBSERVED AND THE LOT IS ACCEPTED




Accept Lot


D - 5%



D - 15%

Correct
Decision
pj - 0.69
C3 - -155


	

Incorrect
Decision
	
	


P2 = 0.31
C4 - -800 - 155

Net Value ($)
PXC3 = -$107



P2C4 = -$296

Cost
                                                               - -$403
The  value  PjCp*)  ln the above table is the probability that the lot is
5%  (15Z) defective given that 0 defectives have been observed.   For
example ,
                                   91

-------
                  /probability that the lot is 5X defective\
            	\   and 0 defectives are observed	/	
   pl  "  ~7lot is 5X defective and\  t/lot is 15* defective and>
          p\ 0 defectives observed /      \ 0 defectives observed  )
          0.5(0.69)  + ' 0.5(0.31)
                  /probability that the lot is 15Z defective)
            	\   and 0 defectives are observed         /
   P2  "   /lot is 5Z defective and
          p\ 0 defectives observed
                   A  +   /lot is 15Z defective and\
                   /     P\ 0 defectives observed  /

0.5(0.31)
          0.5(0.31)  +  0.5(0.69)
                                   -  0.31
It was assumed that the probability that the lot is 51 defective is 0.5.
The probability of observing zero defectives, given the lot quality is
5% or 15X, can be read from the graph of Figure ISA.

A similar table can be constructed for 1, 2, ..., defectives and the net
costs determined.  The net costs are tabulated in Table 10 for 1, 2, and
3 defectives.  The resulting costs indicate that the decision preferred
from a purely monetary viewpoint is to accept the lot if 0 defectives are
observed and to reject it otherwise.  The decision cannot be made on this
basis alone.  The details' of the audit scheme also affect the confidence
which can be placed in.the data qualification; consideration must be
given to that aspect as well as.to cost.
                     Table 10.  COSTS IN DOLLARS

Decision
Reject Lot
Accept Lot

0
-445
-403
d • number of
1
-155
-635
defectives
2
+101
-839

3
+207
-928
Cost Versus Audit Level

After the decision criteria have been  selected,  an  average  cost  can be
calculated.  Based on the results of Table  10, the  decision criterion
is to accept the lot if d - 0 defectives  are  observed  and to reject the
lot if d • 1 or more defectives are observed.  All  the assumptions of the
previous section are retained.  The auditing  level  is  later varied to obtain
the data in Figure 20, page 95.
                                     92

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One example calculation is given below and summarized in Table 11.  The
four cells of Table 11 consider all the possible situations which can
occur, i.e., the lots may be bad or good and the decision can be to
either accept or reject the lot based on the rule indicated by Table 10.
The costs are exactly as indicated in Tables 9A and 9B.  The probabili-
ties are computed as follows.
         •  (prob. that the lot is 51 defective and 1 or more
            defects are obtained in the sample)

         -  (prob. that the lot is 5% defective)(prob. 1 or
            more defectives are obtained in the sample given
            the lot is 5% defective)

         -  0.5 (0.31)  -  0.155
Similarly q_, q_, and q, in Table 11 are obtained as indicated below.


     q£  -  0.5  (0.69)  -  0.345

     q3  =  0.5  (0.69)  «  0.345

     q   =  0.5  (0.31)  -  0.155  .
The sum of all the q's must be unity as all possibilities are  considered.
The value of 0.5 in each equation  is the assumed proportion of good  lots
(or poor quality lots).  The values of 0.31 and 0.69 are the conditional
probabilities that given the quality of the lot, either d - 0  or  d - 1  or
more defectives are observed in  the sample.  Further details of the
computation are given in the final report of this  contract.

               Table  11.  OVERALL  AVERAGE COSTS FOR ONE
     _ ACCEPTANCE - REJECTION SCHEME   _  _ __

Decision
Reject any lot of
data if 1 or more
defects are found.
Accept any lot of
data if 0 defects
are found.
Good Lots
D - 5%
qx - 0.155
Cx - -$755
q3 - 0.345
C3 - -$155
Bad Lots
D - 15%
q2 - 0.345
C2 - $245
q4 - 0.155
C4 - -$955


q^ + q2C2 - -$ 32

q3C3 + q4C4 ° ~$202

                                                  Average Cost » -$234
                                   93

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In order to interpret the concept of average cost, consider a large
number of data lots coming through the system; a decision will be made
on each lot in accordance with the above, and a resulting cost of the
decision will be determined.  For a given lot, the cost may be any one
of the four costs, and the proportion of lots with each cost is given
by the q's.  Hence the overall average cost is given by the sum of the
product of q's by the corresponding C's.

In order to relate the average cost as given in Table 11 to
the costs given in Table 10, it is necessary to weight the costs in
Table 10 by the relative frequency of occurrence of each observed
number of defectives, i.e., prob(d).  This calculation is made below.


  Mo. of       Decision     Costs ($) from
Defectives       Rule          Table 10        Prob(d)     Cost * Prob(d)

  d - 0          Accept            - 403         0.50            -$201.5

      1          Reject       •     - 155         0.34            -  52.7

      2          Reject              101         0.1255             12.6

      3          Reject              207         0.030               6.2

      4          Reject              244         0.0042              1.0

                                       Totals  0.9997          -$234.4


Thus the value -$234 is the average cost of Table 11 and the weighted
average of the costs of Table  10.  The weights, Prob(d), are obtained
as follows:


  Prob(d-O)  -  Prob(lot is good and d-0 defectives are observed)

             +  Prob(lot is poor quality and d-0 defectives are observed)

             - 0.5(0.69) + 0.5(0.31)  -  0.50  .

This is the proportion of all  lots which will have exactly 0 defectives
under the assumptions stated.  For d - 1, 2, 3, and 4, the values of  the
probabilities In parentheses above can be read from Table  6.

Based on the stated assumptions,  the average cost was determined for
several auditing levels as indicated  in Table  11.  These costs are given
in Figure 20.  One observes from  this figure that n • 7 is cost effective
given that one accepts it only if zero defectives are observed.  (See
curve for d-0.)

If the lots are accepted if either 0 or 1 defectives are observed, then
referring to the curve d <_ 1,  the best sampling level Is n -  14.  The
curve of probability of d - 0  (d £ 1) defectives  in a sample of n  from a
lot of N - 100 measurements, given that there  are 10% defectives  in  the
lot, is also given on the same figure.
                                     94

-------
                       Probability

                       if d -  0
                                                            I

                                                            Q
                                                             0)
                                                             N
                                                             0)
                                                            tH
                                                             o.
                                                            en
                                                             0>

                                                             01
                                                             o
                                                             at
                                                             <*j
                                                             ai
                                                             o
                                                             00
                                                             c
                                                             (LI
                                                             ca
o

>»
                                                             (0

                                                             •8
            5            10           15



            Audit Level  (Sample Size)
Figure  20:   Average Cost Vs.  Audit Level

                 (Lot Size N = 100)
                    95

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Another alternative is to accept all data without performing an audit.
Assuming that one-half (50%) of the lots contain more than 10% defectives,
the average cost on a per lot basis would be 0.5(-$800) = -$400.  This,
however, would preclude qualification of the data.  Regardless of cost,
it would be an unacceptable alternative.

DATA QUALITY ASSESSMENT

In this section, approach 2 is considered; that is, the precisions and
biases of the individual measurements and operational procedures are
estimated.  These results are then used to make an assessment of the
data quality.  Although it is theoretically possible to make an overall
assessment, e.g., similar to what was done in the collaborative test
program, this is not a practical possibility due to the high cost.  The
following audit scheme is one which is considered reasonable in both cost
and effort.

Assessment of Individual Measurements

Assume for convenience that an auditing period consists of N = 100 days
(or sampling periods).  Subdivide the auditing period into n equal or
nearly equal periods.  Make one audit during each period and compute the
deviations (differences) between the audit values and the stated values
(or previously determined values as measured by the operator) as indicated
in the Supervision Manual.  For example, if seven audits (n = 7) are to be
performed over 100 sampling periods (N = 100), the 100 periods can be
subdivided into 7 intervals (6 with 14 periods and 1 with 16 periods).
Select one day at random within each interval and perform the suggested
audits.  The operator should not be aware of when the checks are to be
performed.

For sites operating every sixth day, a minimum of three audits per quarter
is recommended.   Samples from individual sites can be grouped into logical
lots, e.g., all sites for which a single operator is responsible, to form
data lots of at least 50 samples.  This approach insures that the audit
level will exceed n = 7 for the combined sites and resulting data.

In order to assess the data quality using measures of bias/precision, the
checks are to be combined for the selected auditing"period, and the mean
difference or bias and the standard deviation of the differences are to
be computed as indicated below.

The formulas for average bias and the estimated standard deviations are
the standard ones given in statistical texts (e.g., see Ref. 9).  The
level of sampling or auditing, n, will be considered as a parameter to
be selected by the manager to assess the quality of data as required.
                                    96

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      (1)  Flow Rate/Volume Check
                                       n
                          Bias = d,
                                  '1      n

where

          d.. . = percent difference in the average flow rate
                using the three-point and two-point approxi-
                mation, or if suitable instrumentation can be
                obtained to measure the integrated volume, the
                percent difference in volumes computed by the
                auditing equipment and by regular means using
                the initial and final flow rates (see page 46).
              Standard Deviation = s^

where

          
-------
          Standard Deviation

where
                                   .K.i - v2
                                  V    .-i     •
           «  ° the  average bias, and

          s.  = the  estimated standard deviation of  the
               differences in the measured and known
           .
               concentration of control samples.


     (3)  Data Processing  Check
                                      n


                         Bias = d
                                 ,           ,
                                 J      n

where

          d,. = percent  deviation of the concentration of SO^
                as  calculated by the operator and by  that
                calculated from the audit.
              Standard Deviation = s» =
                                       >J«  - V
                                     ~\     n  - 1
where
           d, = the  average bias, and

           s_ = the  estimated standard deviation of  the
                data processing errors.


Individual checks on the standard deviations of the three audits  can be
made by computing the  ratio  of  the estimated standard deviation,  s , to

the corresponding suggested  performance standard, 0 , given in  Table 12.

If this ratio exceeds  values given in  Table 12 for any one of the two
audits, it would indicate that  the source of trouble may be assigned to
that particular aspect of the measurement process.  Critical values of
this ratio are given in Figure  21 as a function of sample size  and two
levels of confidence.   Having assessed the general problem area,  one then
needs to perform the appropriate quality control checks to determine the
specific causes of the large deviations.


                                    98

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                   Table 12.   CRITICAL VALUES OF s./o

Level of
Confidence Statistic
90% sjL/a1
95% si/ai
•L X
Audit Level

n=5
1.40
1.54

n-10 n-15
1.29 1.23
1.37 1.30

n-20
1.20
1.26

n-25
1.18
1.23
 s.  = estimated standard deviation

 o.  = hypothesized or suggested standard deviation.
                 Audit
      Flow Rate (or Volume)  theck

      Control Sample

      Data Processing Check
Suggested Performance Standard
o1 = 0.025 x yg SO

o2 = 0.4 yg S02*

a  = 0.03 * yg S02/m3
*a  is based on information in Ref. 6 it must be converted to a percent
 for use in the following subsection.

Overall^ Assessment of Data Quality

The values of d^, d2, d^, s.^, s2 and s» above measure the bias and

variation of the reported data for the three selected audits.  As stated
previously, these three audits do not completely evaluate the measurement
process.   A partial or limited evaluation is used because of the high cost
of a complete evaluation and the unavailability of a cheap and reliable
method of generating test atmospheres of specified concentration with high
precision from one laboratory to another.  These three measures can be
combined to estimate the bias and standard deviation of that aspect of the
process which is audited.  The standard deviation of the measured concentra-
tion of S02 is calculated by using the individual standard deviations expres-
sed in percent error as
                       (in %)
                                     99

-------
     1.60
     1.50
m

o
o


-------
Using the estimated coefficient of variation OT (in percent) and the
mean concentration of SCL one obtains
               ST (yg S02/m3) = 3T (in %)  • yg S02/m3  ,


an estimated standard deviation of the part of the measurement process
which is audited.

Development of a Model - The final report  of this project discusses a
modeling technique for combining the errors of observation and/or the
variation of environmental effects to make an overall  assessment and the
assumptions required in the use of the technique.  The basis for the model
is the equation for the measured concentration of S0~, i.e.,


                           ,   (A - A ) 103 B
          (1)      yg S02/mJ	2_	-S. x D
                                       R

where the individual parameters are defined in the Federal Register and
included in the Appendix for convenience.  Each of the variables in
equation (1) is further modeled in terms of the errors/variations in the
method of measurement, operator, and environmental effects as described in
the final report on this project.  When the model is completely formulated,
an analysis of the mean concentration (or bias) and its estimated standard
deviation can be performed.  For the assumed variations in each of the
variables the bias was negative and about  5%, the standard deviation was
                                 3
about 10%, both based on 400 yg/m  as the  true concentration.  The bias
estimate can be obtained by substituting into the computational formula
            3
for yg S02/m  the averages adjusted for the measured biases and thus

estimating the bias on the reported concentration.  This calculated bias
is denoted by T.  The composite of these two measures  into a mean square
error (MSE), i.e.,
                 MSE ="y(Bias effect)2 + (Std. Dev.)2

                     = 11.2%
yields a value which might be compared to reproducibility of results
obtained in the field.  It must be emphasized that to obtain these
results, estimates of the standard deviations of results were obtained from
Ref. 6 when available and by statistical or engineering judgment otherwise.
                                    101

-------
The estimates of T and a obtained from the model can be used in reporting
the bias and precision as suggested by the following.  The true
concentration of SO. should fall in the following interval, where
         3
(yg S00/m )  is the measured concentration,
      *    m

                       (yg S0,/m3)  - T + 25
                             t-    m     —   JL


approximately 95% of the time, or within the interval


                       (yg S0_/m3)  - T + 3o_,
                             *•    m         1
approximately 99.7% of the time.  When computed from audit data,  the
coefficients of o_ are actually dependent on the number of audits conducted,
If n is large, say about 25 or larger, the value 2  (or 3) is appropriate.

In reporting the data quality, the bias, overall standard deviation, and
auditing level should be reported in an ideal situation (see the  section
entitled "Data Presentation" for further discussion).  More restricted
information following approach 1 is suggested in the Supervision Manual
as a minimal reporting procedure.

If the overall reported precisions/biases of the data meet or satisfy the
requirements of the user of the data, then a reduced auditing level may be
employed; on the other hand, if the data quality is not adequate, assign-
able causes of large deviations should be determined and appropriate
action taken to correct the deficiencies.  This determination may require
increased checking or auditing of the measurement process as well as the
performance of certain quality control checks, e.g., monitoring of
temperature variations over the 24-hour sampling period.

Identification of the Important Parameters - The next step in the modeling
process was to use the model to identify the critical parameters, i.e.,
those parameters which may cause the greatest variation in the measured
concentration, SO., if their variation is of the order of magnitude assumed
in the analysis.  Two types of analyses were employed to determine the
critical parameters and the combined effect of all the parameters on the
                                                   3
variation in the measured concentration of yg S0_/m .

The first type was a sensitivity or ruggedness analysis which identified
and ranked the critical parameters, made certain checks on the adequate
of a linear approximation to the developed model, and estimated the
variation (as measured by the standard deviation) of SO. through  the use of
a linear approximation.  This latter technique was a straightforward
                                   102

-------
application of error analysis.  The second analysis procedure was a
Monte Carlo simulation in which each of the parameters was assigned a
distribution of values:  for example, the slope of the calibration curve
was assumed to be normally distributed with given mean and standard
deviation.  This simulation analysis provided a listing of the simulated
values of concentration in ascending order and calculated the mean and
standard deviation and other pertinent characteristics of this distri-
bution.  These analyses are described in further detail in the final
report of this contract.

Results from the above analyses may not be valid for one specific
situation, but should be a reasonably good evaluation of average precision
and accuracy obtainable over a large population of measurements.  The
results indicate that if the operating procedures recommended in the
Operations Manual were adhered to, the measured data would have a mean value
negatively biased from the true value of concentration (about) 5%, and a
standard deviation of approximately 10% of the mean value
             	  o                                          3
(3_ = 0.10 x ug S02/m ) for a true concentration of 400 yg SOj/m .

Values derived from the above analyses were used to arrive at suggested
performance standards, and to a certain extent, for suggested control
limits given for certain checks in the Operations Manual.

The standard deviation of SCL is a measure of the precision or variation
of the reported values of S0_ as estimated by the model.  It is to be
noted that this measure depends on the estimated standard deviations of
each of the variables and on the coefficients in the model, which are
dependent on the form of the model.  These values can be checked using
the biases and standard deviations computed from actual field data.
                                            v
DATA QUALITY VERSUS COST OF IMPLEMENTING ACTIONS

The discussion and methodology given in a previous section were concerned
with the auditing scheme (i.e., level of audit or sample size, costs
associated with the data quality, etc.).  Increasing the level of audit
of the measurement process does not by itself change the quality of the
data, but it does increase the information about the quality of the
reported data.  Hence, fewer good lots will be rejected and more poor
quality data will be rejected.  If the results of the audit imply that
certain process measurement variables or operational procedures are major
contributors to the total error or variation in the reported concentration
of SO™, then alternative strategies for reducing these variations need to

be investigated.  This section illustrates a methodology for comparing the
strategies to obtain the desired precision of the data.  In practice it
would be necessary to experiment with one or more strategies, to determine
the potential increase in precision, and to relate the precisions to the
relative costs as indicated herein.  Several strategies are considered,
but only a few of the least costly ones would be acceptable, as illustrated
in Figure 22.  The assumed values of the standard deviations and biases for
each strategy and audit are not based on actual data, except for the
reference method.  In this case values were taken from the results of the
collaborative test program (Ref. 6).
                                   103

-------
 Several  alternative actions or  strategies  can be taken  to  increase  the
 precision of  the reported data.  For example, if'the  temperature variations
 are large,  the measurement methods may vary and, cause  variation in
         o
 lag SOj/m .  Under these conditions additional control equipment for
 temperature variation can reduce the variation of  the measured responses
 by calculated amounts and thus  reduce the  error of the  reported concen-
 trations.   In this manner, the  cost of the added controls  can be related
 to the data quality as measured by the estimated bias/precision of  the
 reported results.

 In order to determine a cost efficient procedure,  it  is necessary to
 estimate the variance for each  source of error (or variation) for each
 strategy and then to select the strategy or combination of strategies
 which yields the desired precision with minimum cost.   These calculations
 are summarized in Table 13 with assumed costs of equipment and control
 procedures.  The various strategies are given in Table  5 of Section III.

 Suppose that it is desired to make a statement that the true SO- concen-
                           %                                    £.
 tration is  within 12% of the measured concentration (for simplicity of
 discussion  all calculations were made at a true concentration of

 380 ug/m )  with approximately 95 percent confidence.  Minimal cost  control
 equipment and checking procedures are to be employed  to attain this
 desired precision.  Examining the graph in Figure  22  of cost versus
 precision,  one observes that A2 is the least costly strategy that meets
 the required goal of 2MSE £ 12 or MSB <_ 6  percent.  The mean square error
 (MSB = /a2  + r2) is used in this analysis  as a means  of combining the
bias (T) and standard deviation (a) to obtain a single  measure of the
 overall dispersion of the data.  The assumed values of  the MSB's of the
measured concentrations of S0» for the alternative courses of action are
 given in Table 13.  The costs for the various alternatives are given in
 Table 5 of  Section III and in Table 13.

 Suppose that it is desired that MSE be less than b% and that the cost of
 reporting poor quality data increases rapidly for  MSE greater than  4%, then
strategy A6 = (A2 + A4) appears best because it meets the  goal of MSE being
 less than 4%, its costs of implementation  is $400/100 samples.  However,
 strategy A5 costs $215 to implement and results in a  cost  of about  $40 for
 reporting poor quality data; an overall cost of $255  compared to $400 for
A6.  Based  on the assumed values A5 would  be best.  This example demon-
strates the need for the manager to obtain estimates  of the improvements
 in data quality which can be attained through various actions.  This
assumption  is illustrated by the cost curve given  by  the solid line in
Figure 22^  For any alternative strategy,  the cost of reporting poor
quality data is given by the ordinate of this curve corresponding to the
strategy.
                                    104

-------
o
Ul

,rt 400
\jj
LJ
_J
O_
^^r

§ 300
a:
LJ
a.
"2" 200
h-
(/)
O
0
Q
LJ
g 100
^






A7 = (AI + A2 + A4 )
\ 0A6 = (A24-A4) •
\ 1
\ 1
\ 1
\ 1 COST OF REPORTING
\ / POOR QUALITY DATA
\ 1 '^^^
BEST \ /-* 	
STRATEGIES \ / A3
'•^ \ 1 Q
~~~-~^ 	 ^ \ /
\ i5s(M+fiL
\ A2 I
A4 \ * /
\ /
\ /
v/
\
/ N\
/ \
/ \
/ \
/ \
/ \
/ \AI
/ , V AO
A \ 1 IX 1 1 **f 1
	 ^>
04 5 6 7 8 9
                                                  MSE (PERCENT)

                               Figure 22:  Added Cost ($) vs. MSE (%)  for Alternative Strategies

-------
  Table  13.  ASSUMED STANDARD DEVIATIONS FOR ALTERNATIVE STRATEGIES-'
                                                                    I/
1. Flow rate d
°1
2. Control d.
s ample
°2
3. Data d
processing
°3
CTT (%)
Negative bias = -(%)
MSE(%)-/
Added cost ($) per
100 samples
AO
-4
°1
0
°2
0
G3
5.0
4
6.5
0
Al
-4
0<6ai
0
a2
0
°3
4.7
4
6.2
15
A2
-4
°1
0
0.7o2
0
a3
5.1
1
5.2
200
A3
-4
01
0
0.8a2
0
a3
4.7
4
6.2
260
A4
-3
0.7a
0
0.8a2
0
0.7a3
3.8
3
4.8
200
A£'
-3
0.42^
0
0.8a2
0
0.7a3
3.5
3
4.6
215
*&
-1
0.7a
0
0.56a2
0
0.7a3
3.8
1
3.9
400
AT*/
-1
0.42a1
0
0.56a2
0
0.7a3
3.5
1
3.7
415
I/                                                      31
— a  = 0.4 ug S02, for a  24-hour  sample at  380 yg S02/m  where 0.32 m  of air


       is sampled, a_ = 0.4  y   SO-  is  equivalent to a standard deviation of 3.3%.



  a  and o_ are assumed to be  2.5%  and 3% respectively of the average or mean

         -                3
  value, X = 380 yg S02/m .



  d  is also expressed as  the  bias  in  % of  the mean concentration,


  X - 380 pg S02/m3.



2/
-A5 = .Al + A4, A6 = A2 + A4,  A7  =  Al  + A2  + A4.



3/      /~2    2    2~
— o_ = Wan + a. + a- = percent variation in measured concentration of S0_,
   •L   T X    fc    J                          '         
-------
DATA PRESENTATION

A reported value whose precision and accuracy  (bias) are unknown is of
little, if any, worth.  The actual error of a  reported value—that is,
the magnitude and sign of its deviation from the true value—is usually
unknown.  Limits to this error, however, can usually be inferred, with
some risk of being incorrect, from the precision of the measurement
process by which the reported value was obtained and from reasonable
limits to the possible bias of the measurement process.  The bias, or
systematic error, of a measurement process is  the magnitude and direction
of its tendency to measure something other than what was intended; its
precision refers to the closeness or dispersion of successive independent
measurement generated by repeated applications of the process under
specified conditions, and its accuracy is determined by the closeness to
the true value characteristic of such measurements.

Precision and accuracy are inherent characteristics of the measurement
process employed and not of the particular end result obtained.  From
experience with a particular measurement process and knowledge of its
sensitivity to uncontrolled factors, one can often place reasonable
bounds on its likely systematic error (bias).  This has been done in the
model for the measured concentration as indicated in Table 13.  It is
also necessary to know how well the particular value in hand is likely to
agree with other values that the same measurement process might have
provided in this instance or might yield on measurements of the same
magnitude on another occasion.  Such information is provided by the
estimated standard deviation of the reported value, which measures (or is
an index of) the characteristic disagreement of repeated determinations
of the same quantity by the same method and thus serves to indicate the
precision (strictly, the imprecision) of the reported value.

A reported result should be qualified by a quasi-absolute type of statement
that places bounds on its systematic error and a separate statement of its
standard deviation, or of an upper bound thereto, whenever a reliable
determination of such value is available.  Otherwise, a computed value of
the standard deviation should be given together with a statement of the
number of degrees of freedom on which it is based.

As an example, consider strategy AO in Table 13.  Here, the assumed
standard deviation and bias for a true SO- concentration of 380 yg S02/m

are OT - 19 ug S02/m3 (5.0% of 380 pg/m3) and  T - -15 vg S02/m3,
respectively.  The results would be reported as the measured concentration

(yg S0,/m )  minus the bias and with the following 2a limits along with
      i    m
the audit level and lot size Nj e.g.,


                (yg S00/m3)  + 15 + 38, n - 7, N - 100.
                      z    m
                                    107

-------
 For  concentration other  than  380 yg SO./m  , the overall standard deviation
 is obtained by
                             I  o     o    o
                       /at\    }**.&.£•      -
                    O_CA) " V°1   °  + °o  » an°
                             »  *     O    *
                                    /
                a  (yg/m ) - aT(%) x yg SO./m  .
PERSONNEL REQUIREMENTS

Personnel requirements as described here are in terms of the pararosaniline
method only.  It is realized that these requirements may be only a minor
factor in the overall requirements from a systems point of view where
several measurement methods are of concern simultaneously.

Training and  Experience

Director -  The  director  or  one of the  professional-level  employees,  in
addition to formal  training in chemistry,  should  have  a basic  understanding
of  statistics as used  in quality control.  He  should be able  to  perform
calculations, such  as  the mean and  standard  deviation,  required  to  define
data quality.   The  importance  of and requirements for  performing independent
and random  checks as part of the auditing  process must be understood.   Three
references  which treat the  above-mentioned topics are  listed below:

     Probability and {Statistics for Engineers. Irvin Miller and
     John E. Freund, published by Prentice-Hall, Inc., Englewood,
     N. J.,  1965.

     Introductory Engineering Statistics, Irwin Guttman and
     S. S.  Wilks,  published by John Wiley and Sons, Inc., New York,
     N. Y.,  1965.

     The Analysis of Management Decisions, William T. Morris,
     published by Richard D. Irwin,  Inc., Homewood, Illinois, 1964.

Operator - There are or can be two levels of operation involved in the
manual pararosaniline method.

First, an operator or chemist involved in the reagent preparation or
analysis should have formal training in chemistry.  A person with a
technical or community college background in chemistry with on-the-job
experience and close supervision from an experienced chemist could
adequately prepare reagents and analyze S0_ samples.

Field operations involve sample collection and handling only and require
no high-level skills.  A high school graduate with proper supervision and
on-the-Job training can become effective at this level in a very short time.
                                   108

-------
An  effective  on-the-job  training program could  be as follows:

      (1)  Observe  experienced  operator perform  the different tasks
          in  the measurement process.

      (2)  Study the operational  manual of this  document and use it
          as  a guide  for performing  the operations.

      (3)  Perform  operations under the direct supervision of an
          experienced operator.

      (4)  Perform  operations independently but  with a high level
          of  quality  control checks  utilizing the technique
          described in the  section on  Operator  Proficiency
          Evaluation  Procedures  below  to encourage high quality
          work.

Another alternative would be to  have the operator attend an appropriate
basic training course sponsored  by EPA.

OPERATOR PROFICIENCY  EVALUATION  PROCEDURES

One technique which may  be  useful for  early training and qualification
of operators  is a  system of rating the operators  as indicated  below.

Various types of violations (e.g., invalid sample resulting from operator
carelessness, failure to maintain records, use  of improper equipment,  or
calculation error) would be assigned a number of  demerits depending upon
the relative  consequences of the violation.  These demerits could then be
summed over a fixed period  of  time of  one week, month,  etc., and a
continuous record  maintained.  The mean and standard deviation of the
number of demerits per week can  be determined for each operator and a
quality control chart provided for maintaining  a  record of proficiency of
each operator and  whether any  changes  In this level have occurred.  In
comparing operators,  it  is  necessary to assign  demerits on a per unit  work
load basis in order that the inferences drawn from the chart be consistent.
It 4& not wuc.u>t>
Of$ evaJLuation.  The. &upeA\>e. -i/t at> a. me.an& o
when and what kind o£ ini>tsiu.c£ioni> and/'on training 4Jt> needed.

A sample QC chart  is  given  in  Figure 23 below.  This chart assumes that
the mean and standard deviation  of the number of  demerits per week,
are 5 and 1, respectively.  After several operators have been evaluated
for a few weeks, the  limits can  be checked to determine if they are both
reasonable and effective in helping  to improve  and/or maintain the quality
of the air qulaity measurement.

The limits should be  based  on  the operators whose proficiency is average
or slightly better than  average.   Deviations outside the QC limits, either
above or below, should be considered in evaluating the operators.  Identify-
ing those operators whose proficiency  may have  improved is just as important
as knowing those operators  whose proficiency may  have decreased.


                                   109

-------
The above procedure may be extended to an entire monitoring network (system),
With appropriate definitions of work load, a continuous record may be
maintained of demerits assigned to the system.  This procedure might serve
as an incentive for teamwork, making suggestions for improved operation
procedures, etc.
                      1234   5  6   7   8   9   10  11  12  13
                            Time  Intervals  (Weeks)
   Figure  23:   Sample  QC  Chart  for  Evaluating  Operator Proficiency
                                  110

-------
                             REFERENCES
1.  J. P. Lodge, Jr. et al., "The Use of Hypodermic Needles as Critical
    Orifices in Air Sampling," Journal of the Air^ Pollution Control
    Association 16 (4), April 1966, pp. 197-200.

2.  F. P. Scaringelli, B. E. Saltzman, and S. A. Frey, "Spectrophoto-
    metric Determination of Atmospheric Sulfur Dioxide," Analytical
    Chemistry 39, page 1709, December 1967.

3.  Metronics Dynacal Permeation Tubes, Product Bulletin No. 20-70,
    Metronics Associates, Inc., Palo Alto, Calif. 94304.

4.  F. P. Scaringelli et al., "Preparation of Known Concentrations of
    Gases and Vapors with Permeation Devices Calibrated Gravimetrically,"
    Analytical Chemistry 42 (8), July 1970, pp. 871-876.

5.  B. E. Saltzman et al., "Volumetric Calibration of Permeation Tubes,"
    Environmental Science and Technology 3 (12), December 1969,
    pp. 1275-1279.

6.  H. C. McKee et al., "Collaborative Study of Reference Method for
    Determination of Sulfur Dioxide in the Atmosphere (Pararosaniline
    Method)," Southwest Research Institute, Contract CPA-70-40, SwRI
    Project 21-2811, San Antonio, Texas, September 1971.

7.  "Tentative Method of Analysis for Sulfur Dioxide Content of the
    Atmosphere (Colorimetric)," in Methods of Air Sampling and Analysis,
    Intersociety Committee, published by American Public Health
    Association, Washington, D. C., 1972.

8.  Kenneth D. Reiszner and Philip W. West, "Collection and Determination
    of Sulfur Dioxide Incorporating Permeation and West-Gaeke Procedure,"
    Environmental Science and Technology 7 (6), June 1973, pp. 526-531.

9.  John Mandel, The Statistical Analysis of Experimental Data,
    Interscience Publishers, Division of John Wiley & Sons, New York, N.Y.,
    1964.
                                  Ill

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                APPENDIX

REFERENCE METHOD FOR THE DETERMINATION
   OF SULFUR DIOXIDE IN THE ATMOSPHERE
         (PARAROSANILINE METHOD)
Reproduced from Appendix A, "National Primary and Secondary
Ambient Air Quality Standards," Federal Register, Vol 36,
No. 84, Part II, Friday, April 30, 1971.
                   112

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                                                   GULES AND  REGULATIONS
 APPENDIX  A.—REFERENCE  METHOD  roR THE
   DETEnuiNxnoN or SULFUR DIOXIDE IN THE
   ATMOSPHERE  (PABAROSANIUNE METHOD)

   1. Principle and Applicability.  1.1  Sulfur
 dioxide Is absorbed from air In a solution of
 potassium  tetrachloromercurate  (TCM).  A
 dlchlorosulfltomercurate complex, which re-
 sists oxidation  by the oxygen In the air, is
 formed (1. Z). Once formed, this complex is
 stable to strong oxldants (e.g., ozone, oxides
 of nitrogen)* The complex la reacted with
 pararosanlllne and formaldehyde to form In-
 tensely colored pararosanlllne methyl  sul-
 fonlc acid (J).  The absorbance of the solu-
 tion Is measured  spectrophotometrlcally.
   1.3  The method In applicable to the meas-
 urement  of sulfur dloxldo In ambient  air
 uolng sampling periods up to 24 hours.
   2. Rcnge and Sensitivity. 3.1  Concentra-
 tions of sulfur dioxide in the range of 36 to
 l.OSO Mg/m.° (0.01 to 0.40 p.p.m.) con be meas-
 ured under  the conditions given. One can
 measure concentrations below 38 Mg./m.° by
 sampling larger volumes of air,  but only If
 the absorption efficiency of the particular sys-
 tem Is  first  determined. Higher  concentra-
 tions can be  analyzed by using  smaller goo
 samples, a larger collection volume, or a suit-
 able aliquot of the collected sample. Beer's
 Law Is followed through the working range
 from 0.03 to 1.0 absorbance units (0.8 to 37
 vg. of sulftte Ion In 26 ml. final solution com-
 puted as SO:).
   2.2  The lower limit of detection of sulfur
 dioxide In 10 ml. TCM Is 0.76 vg., (based on
 twice the standard deviation) representing a
 concentration of 26 (ig./m:aOj (0.01  p.p.m.)
 In an air sample of 30 liters.
   3. Interferences. 3.1  The effects  of the
 principal  known  Interferences  have been
 minimized or  eliminated.  Interferences  by
 oxides of nitrogen are eliminated by sulfamlc
 acid  (0,  5), ozone by time-delay (6). and
 heavy  metals by  EDTA (ethylenedlamlne-
 tetroacetlc acid, dlsodlum  salt)  and phos-
 phoric acid (4, 6,). At least 80 ng. Fa (III),
 10 vg. Mn(II). and 10 tig. Cr(III) In 10 ml.
 absorbing  reagent  can be  tolerated In the
 procedure. No significant  Interference  was
 found with 10 MB. CU  (II)  and 22 *g. V(V).
  4.  Precision, Accuracy, and Stability. 4.1
 Relative standard deviation  at the 96 percent
 confidence level Is 4.6 percent for the ana-
 lytical procedure using standard samples. (5)
  4.2 After sample collection the solutions
 ore relatively stable. At 22* C. losses of sulfur
 dioxide occur at the  rate of 1 percent per
 day. When  samples are stored at 6*  C. for
 30 days,  no detectable losses  of sulfur diox-
 ide occur.  The presence of EDTA enhances
 the stability of SO, In  solution, and the rate
 of decay Is Independent of the concentration
 of SOi. (7)
  5.  Apparatus.
  S.I  Sampling.
  5.1.1  Absorber.  Absorbers  normally used
 In air pollution sampling are acceptable for
 concentrations above 25 /ig./m.« (0.01 p.p.m.).
 An all-glass  midget Implnger, as shown in
 Figure Al, Is recommended for 30-mlnute and
 1-hour samples.
  For 24-hour sampling, assemble an ab-
sorber from the following parts:
  Polypropylene 2-port tube closures, special
manufacture (available from Bel-Art Prod-
ucts, Pequannock, N.J.).
  Glass Implngers,  6  mm. tubing, 6 Inches
lone, one end drawn to small diameter such
i'in-  No.  79 jewelers will pass through, but
No. 78 jewelers will  not.  (Other end  fire
polished.)
  Polypropylene tubes, 164  by 32 mm. Nal-
gene or equal).
  5.1.2  Pump. Capable of  maintaining an
air pressure differential greater than 0.7 at-
mosphere at the desired flow  rate.
  5.1.3 Air Flowmeter  or  Critical  Orifice.
A calibrated rotameter or critical  orifice ca-
 pable of measuring air flow within ±2 per-
 cent. For  30-mlnute  sampling,  o 22-gauge
 hypodermic needle 1 Inch long may be used
 as a critical orifice to give a flow of about 1
 liter/minute.  For  1-hour  oampilng.  a  23-
 gauge hypodermic  needle five-eighths of an
 inch long may be.used as a critical orifice to
 give a  flow of  about O.B  liter/minute. For
 34 hour sampling,  a  27-gauge  hypodermic
 needle three-eighths of an Inch long may be
 used to give a flow  of about 0.3 liter/minute.
 Use a membrane filter to protect the needle
 (Figure Ala).
  6.2  Analysis.
  5.2.1   Spectrophotometer.   Suitable   for
 measurement of absorbance at 548 nm. with
 an effective spectral band width  of less than
 15 nm. Reagent bland problems may occur
 with   opectrophotometers  having  greater
 spectral band width.  Tho  OTvelongth cali-
 bration of the Instrument ohould be vorlflod.
 If tranamlttanco lo moasurod, this can bo
 converted to aboorbanoa:
               A=logM(l/T)
  6. Reagents.
  6.1  Sampling.
  6.1.1   Distilled water. Must be free  from
 oxldants.
  6.1.2   Absorbing  Reagent  (O.Od M Potaa-
 sium Tetrachloromercurate (TCM) ). Dissolve
 10.86 g. mercuric  ehlorlde, 0.066  g.  EDTA
 (thylenedlomlnetetraocetlc  acid, dlsodoum
 salt), and  6.0 g. potassium chloride In water
 and bring  to mark  In  a 1,000-ml. volumetric
 flask. (Caution: highly poisonous. If spilled
 on skin, flush oS with water Immediately).
 The  pH  of this reagent ohould be approxi-
 mately 4.0, but It hon been shown that there
 Is no appreciable  difference  In collection
 efficiency over the range of pH 8  to pH 3.(7)
 The absorbing reagent Is normally stable for
 6 months.  If a precipitate forma,  discard the
 reagent.
  5.2   Analysis.
  6.3.1  Sul/amic Acid (0.0  percent). Dis-
 solve  0.6 g. sulfamlc acid In 100 ml. distilled
 water. Prepare fresh daily.
   6.2.2  Formaldehyde (0.2  percent). Dilute
 5 ml. formaldehyde solution (36-38 percent)
 to  1,000 ml. with distilled  water.  Prepare
 dally.
   6.2.3  Stock Iodine Solution (0.1 N). Place
 12.7 g. Iodine In a 250-ml. beaker; add 40 g.
 potassium Iodide and 36 ml. water. Stir until
 all Is dissolved, then dilute to 1,000 ml. with
 distilled water.
   3.2.4  Iodine  Solution (0.01 W).  Prepare
 approximately 0.01 N Iodine solution by di-
 luting  60 ml.  of otocts  oolutlon to  SOO  ml.
 with distilled water.
   6.3.8  Starch  Indicator Solution. Triturate
 0.4 Q. soluble starch and 0.003 g. mercuric
 Iodide (preservative) with a little water, and
 add the paste slowly to 200 ml. boiling water.
 Continue boiling until the oolutlon lo clear;
 cool, and transfer to a glass-stoppered bottle.
   6.3.6  Stock  Sodium Thioyul/ate  Solution
 (0.1 N). Prepare a stock solution by dissolving
 35 g. sodium thlooulfate  (NaJSiCa-BHtO)  In
 1,000 ml. freshly boiled, cooled, dlctlllod water
 and add 0.1 g. sodium carbonate to the solu-
 tion. Allow the solution to stand 1 day before
 standardizing.   To  standardize,   accurately
 weigh, to the nearest 0.1 mg., 1.8  g. primary
 standard potassium lodate dried  at  180°  C.
 and dilute to volume In a 600-ml. volumetric
 flask. To  a 500-ml. Iodine flosS, pipet 80  ml.
 of lodate solution. Add 2 g. potassium iodide
 and 10 ml. of 1  N hydrochloric acid. Stopper
 the flask. After 5 minutes, titrate  with otocft
 thloffulfate solution to a palo yollow. Add 8
 ml.  starch Indicator solution  and continue
 the tltratlon until the blue color dlsappaoro.
 Calculate  the   normality  of  the otccS
 solution:
                   W
                N=—X3.80
   N=Normality  of  stock thlosulfate  oolu-
         tlon.
   M=Volume of thlosulfate required, ml.
   w=Weight of potassium lodate, gramo.
             3.80 =
                    10"(conversion of g. tomg.) X0.1 (fraction lodate used)
                         36.67 (equivalent weight of potassium lodate)
  6.2.7  Sodium Thiosulfate Titrant (0.01 N).
Dilute 100 ml. of the stock thlosulfate solu-
tion to 1,000 ml. with freshly boiled distilled
water.
    Normality = Normality of  stock solution
                  X 0.100.
  6.2.8  Standardize  Sulflte  Solution  for
Preparation of Working Sulftte-TCM Solu-
tion.  Dissolve 0.3  g.  sodium  metablsulflte
(NajSA.) or 0.40 g. sodium sulflte (Na.SO,)
In 500 ml. of recently boiled, cooled, distilled
water.  (Sulflte solution  is unstable; it Is
therefore Important to use water of the high-
est purity to minimize this Instability.) This
solution contains the equivalent of 320 to 400
jtg./ml.  of SO,. The actual concentration of
the solution is determined by adding excess
Iodine  and  back-titrating with  standard
sodium thlosulfate solution. To back-titrate,
plpet 50 ml. of the 0.01 N Iodine into each of
two 500-ml. iodine flasks (A and B). To flask
A (blank) add 25  ml. distilled water, and to
flask B (sample) plpet 25 ml. sulflte solution.
Stopper the flasks  and allow to react for  5
minutes. Prepare  the working sulflte-TCM
Solution .(6.2.9)  at the same time  iodine
solution Is added to the flasks. By means of
a buret containing standardized 0.01 N thlo-
eulfate, titrate each flask In  turn to a pale
yellow. Then add 5 ml. starch  solution and
continue the  tltratlon until  the blue color
disappears.
  6.2.9  Working Sulflte-TCM Solution. Plpet
accurately 2 ml. of the standard solution Into
a 100 ml volumetric flask and bring to mark
with 0.04 M TCM. Calculate the concentra-
tion of sulfur  dioxide in the working solu-
tion:
             
-------
                                                 RULES  AND REGULATIONS
 properly standardized.
   6.2.10.2  Preparation o/ Stock Solution. A
 specially purified (M-100 percent pure)  so-
 lution of  pararosanlllne, which meets the
 above ipeclflcatlons, Is commercially avail-
 able  in  the required O.SO percent concen-
 tration  (Harleco*). Alternatively,  the dye
 may  be purified, a stock solution prepared
 and then  assayed  according to  the proce-
 dure of Searlngelll. et al. (4)
   6J.11  Pararotaniiine Reagent. To a 280-
 ml. volumetric flaak, add 20 ml. stock par-
 aroaanlllne solution. Add an additional  0.2
 ml. stock solution for each percent the stock
 assays below 100 percent. Then add 28 ml.
 S If  phosphoric add and dilute to volume
 with  distilled water. This reagent Is stable
 for at least 9 months.
   7. Procedure.
   T.I   Sampling. Procedures are described
 for short-term (SO minutes and 1 hour) and
 for long-term (34 hours)  sampling. One can
 select different  combinations  of iaitir-1'frg
 rate and time to meet special needs. Sample
 volumes should be adjusted, so that linearity
 Is maintained between absorbenee and con-
 centration over  the dynamic range.
   7.1.1  30-Hinute and  1-Hoiir  SompUnps.
 Insert a midget  Implnger Into ^he sampling
 system, Figure Al. Add 10 ml. TOM solution
 to the Implnger. Collect  sample at 1 liter/
 minute for 80 minutes, or at 0.8 liter/minute
 for 1 hour, using  either a rotameter, as
 shown in Figure Al, or a critical orifice, as
 shown in Figure Ala, to control flow. Shield
 the absorbing reagent from direct sunlight
 during  and after sampling  by  covering the
 Implnger  with  aluminum foil, to prevent
 deterioration. Determine the volume of  air
 sampled by multiplying the flow rate by the
 time  In minutes  and record the  atmos-
 pheric pressure  and temperature. Remove
 and stopper the  Implnger.  If  the  sample
 must be stored  for more  than  a day before
 analysis, keep It at 8*  O. In a refrigerator
 (see 4.2).
   7.1.2  M-Hour Sampling.  Place 60  ml.
 TOM  solution in a large absorber and col-
 lect the sample at 03 uter/mlnute for M
 hours from midnight to midnight. Make sure
 no entralnment  of solution results with the
 Implnger. During collection and storage pro-
 tect from  direct  sunlight. Determine the
 total  air volume by multiplying the air flow
 rate by the time In minutes. The correction
 of 24-hour measurements for  temperature
 and pressure Is extremely difficult and Is not
 ordinarily  done.  However, the accuracy of
 the measurement will be improved If mean-
 ingful corrections can be  applied. If storage
 Is necessary, refrigerate at 8* O. (see 4.2).
  7.2  Analytii..
  73.1  Sample Preparation. After collection.
 If a precipitate  Is  observed in the sample,
 remove It by eentrlfugatlon.
  7.9.1.1  SO-tlinute and 1-Wour Sample*.
 Transfer the sample quantitatively to a 38-
 ml. volumetric flask; use about 8 ml. distilled
 water tor rinsing. Delay analyses for SO min-
 utes to allow any ocone to decompose.
  7.2.1.2  tt-Hour Sample. Dilute the entire
 sample  to  80 ml. with absorbing solution.
 Plpet  8  ml. of  the sample Into a SB-mi.
 volumetric flask  for chemical analyses. Bring
 volume  to  10 ml.  with  absorbing  reagent.
Delay analyses for 20 minutes to allow any
ozone to decompose.
  7.2.2  Determination. For each set of de-
 terminations prepare a reagent blank by add-
 ing 10 ml.  unexposed TCM solution to a 28-
mL volumetric flask. Prepare a control solu-
tion by adding 2 ml. of working aulflte-TOIf
solution and 8 ml. TCM solution to a 28-ml.
volumetric flask. To each flask containing el-
  •Hartmen-Leddon,  60th  and
Avenue, Philadelphia, PA 19143.
                                Woodland
ther  sample,  control  solution, or  reagent-
blank,  add  1  ml.  0.8  percent sulfamle
add and allow to  react 10 minutes to de-
stroy the nitrite from oxides of nitrogen.
Accurately  plpet   In  2  ml.  0.2   percent
formaldehyde solution,  then  8 ml.  par-
ameantllne  solution.  Start  a  laboratory
timer that has been set for SO minutes. Bring
al) flasks to volume with  freshly boiled and
cooled distilled water and mix thoroughly.
After 80 minutes and before 60 minutes, de-
termine the absorbanoes of the sample (de-
note as A), reagent  blank (denote as A.) and
the control solution at 648 nm. using l-em.
optical path length cells. Use distilled water,
not the reagent blank,  as the reference.
 (Nonl This Is Important because of the color
sensitivity of the reagent  blank to tempera-
ture changes which can be Induced In the
cell compartment of a spectrophotometer.)
Do not allow the colored solution to stand
In the absorbanee cells, because a film of dye
may be deposited.  Clean  cells  with  alcohol
after use. If the temperature of the determi-
nations does not differ by more than 2* O.
from the calibration temperature (8.2). the
reagent blank should be within 0.03  absorb-
anee unit of the y-intercept of the calibra-
tion curve (8.2). If  the reagent blank differs
by more than 0.03 absorbanee unit from that
found In the calibration curve, prepare a new
curve.
  7.2.8  Aotorbonce Range. If the absorbanoe
of the sample solution ranges between  1.0
and 2.0. the sample can be diluted 1:1 with
a  portion  of  the  reagent blank and read
within a few minutes. Solutions with higher
absorbanee can»be diluted up to sixfold with
the reagent blank in order to obtain onscale
readings within 10  percent  of  the true ab-
sorbanoe value.
  8. Calibration and tglcimciet.
  6.1  riovrtnetert and* Hypodermic  Needle.
Calibrate flowmetera  and hypodermic nee-
dle (•)  against a calibrated wet test meter.
  8.2  Calibration Curves.
  8,3.1  Procedure vtth Sulflte Solution. Ac-
curately  plpet  graduated amount*  of  the
working  sulflte-TCM solution (8.3.9) (such
as 0, OJ, 1, 2, 3, and 4 ml.) Into a series of
28-ml. volumetric flasks. Add sufficient TOM
solution to each flask to bring the volume to
approximately 10 ml. Then add the retraining
reagents as described In 7.3.3. For maximum
precision use a constant-temperature bath.
The temperature  of calibration must  be
maintained within  ±1* C. and in the range
of 20* to SO* O. The temperature of calibra-
tion and the temperature of analysis must be
within 2 degrees. Plot the absorbanee  against
the total  concentration in »g. BO. for the
corresponding solution. The total «g. SOi In
solution' equals  the  concentration  of  the
standard (Section 8.2.9) In t%. BOi/ml. times
the ml.  sulflte solution  added  (ng. BOi=
*g-/ml. BOiXml. added).  A  linear relation-
ship should be obtained, and the y-intercept
should be within 0.03 absorbanee unit of the
•ero standard absorban.ee. For maximum pre-
cision determine the line of best fit using
regression analysis  by the method of least
squares. Determine  the slope of the line of
beet flt, calculate Its reciprocal and  denote
as Bi. Bi Is the calibration factor. (See Sec-
tion 6.2.10.1 for specifications on the slope of
the calibration curve). This calibration fac-
tor can be used  for calculating results pro-
vided  there  are  no  radical  changes  in
temperature or  pR.  At  least  one  control
sample """^'"'"g a known concentration of
8O» for  each series  of  determinations, Is
recommended to Insure the reliability of this
factor.
  933 Procedure   wttv  SO>   Permeation
rubes.
  8.2.2.1  General   Contiaerationt.  Atmos-
pheres containing accurately known amounts
of sulfur dioxide at levels  of Interest can be
prepared  using permeation  tubes.  In the
systems  for  generating these atmospheres,
the permeation tube emits BO,  gas  at a
known, low, constant rate, provided the tem-
perature of the tube Is held constant (±0.1*
C.)  and provided  the tube has been accu-
rately calibrated at the temperature of use.
The BO.  gas permeating  from the tube is
carried by a low flow of inert gas  to a mix-
Ing chamber where  It is accurately  diluted
with 80,-free air to the level of interest and
the sample taken. These systems are shown
schematically In Figures A3 and AS and have
been described In detail  by OKeeffe and
Ortman  («), Scarlngelll, Frej, and Saltaman
(10), and Bcartngelll,  O"Keeff«, Rosenberg,
and Bell (11).
   »333   Preparation  of  Standard  Atmot-
pheret. Permeation tubes may be prepared
or purchased.  Scarlngelll,  O'KeeRe,  Rosen-
berg, and Bell  (11)  give detailed, explicit
directions for permeation tube  calibration.
Tubes with a certified  permeation rate  are
available from the National Bureau of Stand-
ards. Tube permeation rates from  0.2 to 0.4
«g./mlnute Inert gas flows of about 80 ml./
minute and  dilution air flow rates from 1.1
to 16 liters/minutes conveniently give stand-
ard atmospheres containing desired levels
of SO, (28 to 890 fg./m.>; 0.01 to 0.18 p.p.m.
SO.). The concentration of SO, In any stand-
ard atmosphere can be calculated as follows:
                   P*10«
                C=—	
                   R4+R,
Where:
   O = Concentration of SOi, *g./m.3 at ref-
         erence conditions.
   p =Tube permeation rate, *g-/Klnute.
   R<=Flow rate of dilution air, Uter/mlnute
         at reference conditions.
   Ri=Ftow rate of Inert gas, liter/minute at
         reference conditions.
   8.3.3.8   Sampling and Preparation o/ Cali-
bration Curve. Prepare a series (usually six)
of  standard atmospheres containing  8Oi
levels from 28 to 890 M. 8O,/m.'. Sample each
atmosphere using similar apparatus and tak-
ing exactly the same air volume as  will be
done in   atmospheric sampling. Determine
absorbanoes as  directed  In 7.2. Plot the con-
centration of SOi In «g'/m.* (x-axlsy  against
A—A, values (y-ajdi). draw the straight line
of best flt and determine the slope. Alter-
natively,  regression analysis by the method
of least squares may be used to calculate the
slope. Calculate the  reciprocal of  the  slope
and denote as B,.
  8.3 Sampling tfflclency.  Collection  effi-
ciency  la  above 98 percent:  efficiency may
fall off, however, at concentrations below 25
«./m.«. at. 13)
  9. Calculations.
  9.1 Conversion  of  Volume. Convert the
volume of air sampled to the volume at ref-
erence conditions of 26* C. and 760 mm. Rg.
(On 24-hour samples, this may not  be
possible.)            p    m

           Vs=VX—X	
                  760  t+273
   Vt=Volume of air at 28* C. and 760 mm.
         Kg. liters.
   V = Volume of air sampled, liters.
   p = Barometric pressure, mm. Bg.
   t  =Temperature of air sample, *c.
   9 3 Sulfur Dioxide Concentration.
  9.2.1  When sulflte solutions are used to
prepare calibration curves, compute the con-
centration of sulfur dioxide In the sample:

                (A-A.)  (10>)  (B.)
    «g. BO,/m.«=	Y. D
                       Va
   A = Sample absorbanee.
   Ag^Reagent blank absorbanee.
   10>=Conversion of Utere to cubic meters.
   Va =The sample corrected to 28*  C. and
          760 mm. Bg, liters.
                                        HDUA1 ItOISTU, VOL M, NO. 64—MIDAY, APIIL 30, 1971
                                                               114

-------
                           RULES  AND REGULATIONS
  B. =Calibration   factor,  ^g./absorbance
         unit.
  D = Dilution factor.
       For 80-mlnute and  1-bour samples,
         D=l.

       For 24-hour samples, D= 10.

  9.2 J  When 8O> gas standard atmospheres
an used to prepare calibration curves, com-
pute the sulfur dioxide In the sample, by the
following formula:

         80».«[.An.«=(A-A.)XB,

  A = Sample absorbanoe.
  Ao=Reagent blank absorbance.
  B»= (See 8.3.3.3).
  9.3.3  Conversion of n>./m.'  to p.p.m. = lf
desired, the concentration of sulfur dioxide
may be calculated as p.p.m. SO_. at reference
conditions as follows:

    p p.m. SO,=«g. 8O,/m."x3.82 x 10-«
  10.  «e/erence».
  (2) West. P. W., and Oaeke.  O. C.. "Fixa-
       tion of Sulfur Dioxide as Sulntomer-
       curate m and  Subsequent  Colon-
       metric Determination", Anal. Chem.
       28, 1816 (1956).
  (2) Ephralms. P.,  "Inorganic Chemistry,"
       p. 682, Edited by P.C.L. Thorne and
       E. R.  Roberts,  6th Edition,  Inter-
       science. (1948).
  (3) Lyles, O. R., Dowllng, P. B.. and Blanch-
       ard, V. J.. "Quantitative Determina-
       tion of Formaldehyde In Parts Per
       Hundred Million Concentration Lev-
       el", J.  Air Poll.  Cont. Asioc.  IS, 106
       (1986).
  (4) Scarlngelll,  F. P., Saltzman, B.  E., and
       Prey. s. A., "Spectrophotometric De-
       termination  of  Atmospheric Sulfur
       Dioxide", Anal. Chem. 39,1709 (1987).
  (5) Pate, J. B., Ammons,  B.  E., Swanson,
       O. A., Lodge, J.  P., Jr., "Nitrite In-
       terference In Spectrophotometric De-
       termination of  Atmospheric Sulfur
       Dioxide". Anal. Chem. 37.943 (1966).
  <«)  Zurlo, N. and Orlfflnl, A. M.. '•Measure-
       ment of the SO, Content of Air in the
       Presence  of Oxides of Nitrogen  and
       Heavy Metals", Met. Lavoro, S3, 330
       (1983).
 (7)  Scarlngelll, F. P.. Enters, L..  Norrls, D.,
       and Hochhelser,  8., "Enhanced Sta-
       bility of Sulfur Dioxide In Solution",
       Anal. Chem. 42, 1818 (1970).
 (8)  Lodge, J. P. Jr., Pate, J. B.. Ammons,
       B. E.  and Swanson,  a. A.,  "Use of
       Hypodermic Needles as Critical Ori-
       fices In Air  Sampling." J. Air  Poll.
       Cont. Assoc. IS. 197 (1966).
 (9)  O'Keeffe, A. -E.. and  Ortman, O. C.,
       "Primary Standards  for  Trace  Oas
       Analysis". Anal. Chem. 38, 760 (1966).
(10)  Scarlngelll, F. P., Prey, S. A., and Saltz-
       man,  B.  E.,  "Evaluation  of Teflon
       Permeation Tubes for Use with Sulfur
       Dioxide". Amer.  fnd. Hygiene Asaoc.
       J. 28, 260  (1967).
(11)  Scarlngelll. F. P., O'Keeffe. A. E., Rosen-
       berg, E., and Bell, J. P., "Preparation
       of Known Concentrations of  Oases
       and Vapors with Permeation Devices
       Calibrated  Qravlmetrlcally",  Anal.
       Chem. 42, 871  (1970).
(12)  Urone, P., Evans, J. B., and Noyes, C. M.,
       "Tracer Techniques  in  Sulfur  Di-
       oxide  Colorlmetrlc  and  Conductlo-
       metrlc Methods", Anal Chem. 37,1104
       (1968).
(13)  Bostrom, C. B., "The Absorption of Sul-
       fur Dioxide at Low  Concentrations
       (p.p.m.)  Studied  by an  Isotoplc
       Tracer Method",  Intern. J. Air Water
       Poll. 9, 33 (1965).
                                                               HYPODERMIC
                                                                 NEEDLE
                                      Figure A1a. Critical orilice How control.
             WRINGER
                             Figure A1. Sampling train.
              FEDEtAl  REGISTER, VOL 36, NO. 84—ttlCAY, APRIL 30, 1971
                                        115

-------
                    RULES  AND REGULATIONS
  TOHOOO

    J
        THERMOKETHl
                                    FLOWUETER
                                    OR CRITICAL
                                     OfUFICB
                                                      DMBI
                                      ItTIRRER
  MWIATION
           TUMMBaUR
                                          WATER BATH
CYLINDER
> MR OH
MTROOEN
                  Rgm AS. Amnlw lor «MMHo nlMbi ltd fW* •*.
MT1
                HOISTB. VOL M, NO. M—WIOAY, Aftll M, 1*71
                                    116

-------
 BIBLIOGRAPHIC DATA
 SHEET
                      1. Report No.
3. Recipient's Accession No.
4. Title and Subtitle
  GUIDELINES FOR  DEVELOPMENT  OF A QUALITY ASSURANCE PROGRAM -
  Reference Method  for Determination of Sulfur Dioxide in  the
  Atmosphere	
5> Report Date
  July 1973
6.
7. Author(s)
  Franklin Smith  and A. Carl  Nelson, Jr.
8. Performing Organization Kept.
  No.
9. Performing Organization Name,and Address
  Research Triangle  Institute
  Research Triangle  Park, N.  C.  27709
10. Project/Task/Work Unit No.
11. Contract/Grant No.

 EPA  DURHAM 68-02-0598
12. Sponsoring Organization Name and Address
   Environmental  Protection  Agency
   National  Environmental Research Center
   Research  Triangle Park, N.  C.  27711
13. Type of Report & Period
   Covered
 Interim  Contractor's r<
                          port
14.
15. Supplementary Notes
16. Abstracts
   Guidelines for  the quality control  of the Federal reference method  for sulfur
   dioxide are presented.  These include:
   1.  Good operating practices
   2.  Directions  on how to  assess and qualify data
   3.  Directions  on how to  identify trouble and  improve data quality.
   4.  Directions  to permit  design of  auditing activities
   5.  Procedures  for selecting action options and relating  them to costs.

   This  document is  not a research report.   It is for use by operating personnel.
 17. Key Words and Document Analysis. 17a. Descriptors
   Quality Assurance
   Quality Control
   Air Pollution
   Quantiative Analysis
   Gas Analysis
   Sulfur Dioxide
17b. Identifiers/Open-Ended Terms
17c. COSATI Field/Group  13H, 14D,  13B, 07B,  07B, 14B
18. Availability Statement
19.. Security Class (This
   Report)
	UNCLASSIFIED
                                                           20. Security Class (This
                                                              Pa,
                                                                ge
                                                                Ul
                                                                 NCLASS1FIED
           21. No. of Pages
                                                                                  22. Price
FORM NTtS-35 (REV. 3-721
                                                                                  USCOMM-DC 149S2-P72

-------
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   Guidelines to Format Standards  for Scientific and Technical Reports Prepared by or for* the Federal Government,
   PB-180 600).

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       from the performing organization.

   8.  Performing Organization Report  Number.  Insert if performing organization  wishes to assign this  number.

   9-  Performing Organization Name and  Address.  Give name,  street, city, state, and zip code.   List  no more than two levels of
       an organizational hierarchy.  Display the name of the organization exactly as it should appear in Government indexes such
       as  USGRDR-I.

  10.  Projecf/Tosk/Work Unit Number,  list- the project, task and  work  unit numbers under which the report was prepared.

  11.  Contract/Grant Number.  Insert contract  or grant number under which report was prepared.

  12*  Sponsoring Agency  Nome and Address.  Include zip code.

  IX  Type of Report and Period Covered.  Indicate interim, final, etc., and, if applicable, dates covered.

  14*  Sponsoring Agency  Code.   Leave blank.

  15.  Supplementary Notes.  Enter information not included elsewhere but useful,  such a.*- : Prepared in cooperation  with . .  .
       Translation of ...  Presented at conference of . . .  To be published in ...  Supersedes . . .       Supplements . .  .

  16.  Abstract.   Include a brief  (200 words or less)  factual summary  of the most significant information contained in the report.
       If the report contains a significant  bibliography or literature survey, mention it here.

  17.  Key  Words and Document Analysis,  (a).  Descriptors. Select from the Thesaurus of Knginecring and Scientific Terms the
       proper authorized terms that identify the major  concept of the research and are sufficiently specific and precise to be used
       as index entries for cataloging.
      (b).  Identifiers and Open-Ended Terms.  Use identifiers  for project names, code names, equipment designators, etc.  Use
       open-ended terms written  in descriptor form for those subjects for which no descriptor exists.
      (c).   COSATI  Field/Group.  Field  and Group assignments  are to be taken from the 1965 COSATI  Subject  Category  List.
       Since the majority of documents  are multidisciplinary in nature, the  primary Field/Group assignment(s) will be the specific
      discipline, area of human  endeavor, or type of physical object.  The applications ) will be cross-referenced with secondary
       Field/Group assignments  that will  follow the primary posting(s).

  18.  Distribution Statement.  Denote  rcleasability to the  public  or limitation for reasons other than security for example  "Re-
       lease unlimited".  Cite any availability  to the public, v-ith address and price,

  19 & 20.  Security Classification.  Do not submit classified reports to  the National Technical

  21.  Number of Pages.   Insert the total  number of pages,  including this  one  and unnumbered pages, but excluding  distribution
       list, if any.

  22.  Price.  Insert the price set by the  National Technical Information Service or the Government  Printing Office, if known.


FORM NTIS-35 
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