vvEPA
United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
P.O. Box 93478
Las Vegas NV 89193-3478
EPA/600/R-93/109
June 1993
Research and Development
Automated On-Site
Measurement of
Volatile Organic
Compounds in Water
A Demonstration of
the A+RT, Inc.
Volatile Organic
Analysis System
5280GR93QAD.COV
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NOTICE
The information in this document has been funded wholly or in part by the U.S. Environmental Protection
Agency under Contract No. 68-CO-0049 to Lockheed Engineering & Sciences Company and under
Cooperative Agreement No. CR-817552-01-0 to the University of Houston. It has been subjected to the
Agency's peer and administrative review, and it has been approved for publication as an EPA document.
Mention of corporation names, trade names, or commercial products does not constitute endorsement or
recommendation for use.
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Abstract
A demonstration of the performance of the Analytic and Remedial Technology, Inc. Volatile Organic Analy-
sis System (AVOAS) is described. The AVOAS is designed to provide automated collection and analysis
of water samples containing volatile organic compounds (VOCs). In this demonstration, the AVOAS was
used to monitor VOCs at a pilot pump-and-treat ground-water remediation facility. The demonstration was
conducted by the U.S. Environmental Protection Agency (EPA) through the Superfund Innovative Technol-
ogy Evaluation (SITE) Program at a Superfund site in Woburn, Massachusetts in May, 1991.
The AVOAS consists of a manifold which permits sampling from multiple locations; an injector which
extracts the VOCs from aqueous samples by a proprietary process similar to purge and trap and injects
them into a gas chromatograph; and software that provides system control and storage of data. The pro-
posed advantages of the AVOAS are that it eliminates the steps typically associated with collection and
analysis of water samples and provides real-time results.
The demonstration was performed at a site where the ground water is contaminated with volatile chlori-
nated hydrocarbons. The performance of the AVOAS was compared with that of an established method
(EPA Method 502.2). In addition to on-line monitoring of the ground-water treatment system, samples
spiked with measured concentrations of analytes were processed for purposes of evaluation and quality
control. The demonstration was designed to detect sources of variability between the field and conven-
tional laboratory techniques. On the basis of results from this short-term study, we conclude that the
AVOAS is capable of providing the benefits of automated sampling and analysis, as proposed. AVOAS
recoveries for samples spiked with known concentrations of VOCs were higher than those of Method
502.2, and were close to 100% for most analytes. Precision was within limits acceptable for VOC analyses
(within 30 percent relative standard deviation). Further development of the AVOAS is encouraged, and a
longer term evaluation at other sites is recommended.
This evaluation report is submitted by Lockheed Engineering & Sciences Company in partial fulfillment of
Contract Number 68-CO-0049 with the U.S. EPA Environmental Monitoring Systems Laboratory, Las
Vegas, Nevada.
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Table of Contents
Notice ii
Abstract iii
Abbreviations and Acronyms xi
Acknowledgments xiii
Executive Summary xv
1 Introduction 1
SITE Program Background 1
AVOAS Technology Description 1
AVOAS Demonstration Overview 2 .
Purpose of the AVOAS Demonstration 2
Demonstration Site Description 3
Project Organization 3
2 AVOAS Demonstration Design and Activities 9
Demonstration Design 9
Rationale Behind the AVOAS Demonstration Design 9
AVOAS Demonstration Evaluations 10
Demonstration Components 11
Sample Types Analyzed 11
Performance Evaluation Study 13
Quality Assurance for the AVOAS Demonstration 15
Data Quality Objectives 15
Quality Control Samples 17
Demonstration Methods 17
EPA Method 502.2 Requirements and Modifications 17
Sample Analysis 19
Data Management 19
Data Analysis 19
AVOAS Demonstration Activities 21
3 AVOAS Demonstration Results and Discussion 23
Operational Results 23
Quantitative Results for Comparison Studies 23
Comparison of the AVOAS and Method 502.2 Results for Treatment Train Samples 23
Comparison of the AVOAS and Method 502.2 Results for Spiked Purged Effluent
Water Samples 29
Transport Study Results 34
Linearity Study Results 36
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Quality Assurance and Quality Control Results 38
Results for QC Samples 38
Results for Data Quality Objectives 42
Performance and Systems Audits 42
Qualitative Observations 43
Ruggedness and Adaptability 43
Maintenance Requirements 44
Facility and Supplies Requirements 44
System Costs 45
Summary of Results and Discussion 45
4 Conclusions and Recommendations 47
Conclusions 47
Advantages of the AVOAS 47
Limitations of the AVOAS ...48
Limitations of the AVOAS Demonstration 48
Recommendations .....48
Recommendations Specific to the AVOAS 48
Recommendations for Future Studies 49
References 50
vi
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List of Figures
Page
1-1. Schematic of the AVOAS 2
1-2. Area map of the Wells G and H Superfund Site, Wobum, Massachusetts 4
1-3. Schematic of the Unifirst Ground-Water Treatment System 5
1-4. Organizational Structure of the AVOAS Demonstration 6
2-1. AVOAS Demonstration Evaluations 11
3-1. Treatment Train Sample Results. (Overall ports and times.) 28
3-2. Spiked Purged Effluent Water Results 29
3-3a. Transport Study Results for Medium- and High-concentration Spiked Samples for
Trichloroethene 34
3-3b. Transport Study Results for Medium- and High-concentration Spiked Samples for
Tetrachloroethene 35
3-4. Quality Control Check Standard Results 40
VII
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List of Tables
Page
2-1 Sample Types Analyzed for the AVOAS Demonstration 12
2-2 Summary of Analyte Concentrations (ng/L), by Sample Type 13
2-3 Summary of Method Detection Limits (ng/L) for the AVOAS and EMSL-LV
Instruments, by Sample Loop Size, Dilution, and Sample Type 14
2-4 Data Quality Objectives for the AVOAS Demonstration 16
2-5 Method 502.2 Quality Control Requirements 18
2-6 Instrument Components and Operating Conditions 20
2-7 Chronology of AVOAS Demonstration Activities 21
2-8 Schedule of Sample Analyses for the AVOAS and EMSL-LV 22
3-1 (a,b) Treatment Train Sample Results for EMSL-LV and the AVOAS On-line Analyses 24
3-1 (c) Treatment Train Sample Results for the AVOAS Off-Line Analyses 24
3-2(a) Summary of Mean, Standard Deviation, and %RSD for Port Measurements for
EMSL-LV, AVOAS On-LJne, and AVOAS Off-Line Analyses of Treatment Train Samples
Across the Six Days of the Demonstration 25
3-2(b) Summary of Mean, Standard Deviation, and %RSD for Sample Time Measurements for
EMSL-LV, AVOAS On-Line, and AVOAS Off-Line (a.m. and p.m.) Analyses of Treatment
Train Samples Across the Six Days of the Demonstration 26
3-3 Difference in Mean Percent Recoveries for Treatment Train Samples Analyzed by the
AVOAS and EMSL-LV 27
3-4 Summary of Analysis of Variance Results for Treatment Train Samples 27
3-5(a) Low-Concentration Spiked Purged Effluent Water Sample Results for EMSL-LV and
AVOAS Analyses 30
3-5(b) Medium-Concentration Spiked Purged Effluent Water Sample Results for EMSL-LV and
AVOAS Analyses 31
3-5(c) High-Concentration Spiked Purged Effluent Water Sample Results for EMSL-LV and
AVOAS Analyses 32
3-5(d) Superhigh-Concentration Spiked Purged Effluent Water Sample Results for EMSL-LV
and AVOAS Analyses 33
3-6 Difference in Mean Percent Recoveries for Spiked Purged Effluent Water Samples
Analyzed by the AVOAS (Off-Line) and EMSL-LV 34
3-7(a) Transport Study Results for Medium Spiked Samples 35
3-7(b) Summary of Transport Study Results for Medium Spiked Samples 36
3-8(a) Transport Study Results for High Spiked Samples 37
3-8(b) Summary of Transport Study Results for High Spiked Samples 37
3-9(a,b) Quality Control Check Standard Results for EMSL-LV and the AVOAS 38
3-10(a,b) Percent Recoveries for Quality Control Check Standards for EMSL-LV and the AVOAS 39
3-11 (a,b) Percent Differences for Continuing Calibration Check Standards for EMSL-LV and the
AVOAS 41
3-12(a) Percent Recoveries for Spiked Purged Effluent Water Samples for Each Demonstration
Day for EMSL-LV 43
3-12(b) Percent Recoveries for Spiked Purged Effluent Water Samples for Each Demonstration
Day for the AVOAS **
ix
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List of Abbreviations and Acronyms
1,1 -DCA 1,1-dichloroethane
1,1 -DCE 1,1 -dichloroethene
1,1,1 -TCA 1,1,1 ,-trichloroethane
1,2-DCA 1,2-dichloroethane
A+RT Analytic and Remedial Technology, Inc.
AFMMP Advanced Field Monitoring Methods Program
ANOVA Analysis of variance
AVOAS A+RT Volatile Organic Analysis System
CCCS continuing calibration check standard
cis-1,2-DCE cis-1,2-dichloroethene
CLP Contract Laboratory Program
DQO data quality objective
ELCO electrolytic conductivity detector
EMSL-LV Environmental Monitoring Systems Laboratory-Las Vegas
EPA Environmental Protection Agency
EPC Environmental Project Control, Inc.
GC gas chromatograph
HCI hydrochloric acid
LESC Lockheed Engineering & Sciences Company
MDL method detection limit
Method 502.2 EPA Method 502.2, "Volatile Organic Compounds in Water by Purge and Trap Capillary
Column Gas Chromatography with Photoionization and Electrolytic Conductivity
Detectors in Series"
%D percent difference
%R percent recovery
PCE tetrachloroethene (perchloroethene)
PEW purged effluent water
PE performance evaluation
PID photoionization detector
ppb parts per billion
ppm parts per million
PQL practical quantitation limit
QA quality assurance
QAPjP Quality Assurance Project Plan
QC quality control
QCCS quality control check standard
RSD relative standard deviation
RT retention time
SARA Superfund Amendments and Reauthorization Act
xi
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List of Abbreviations and Acronyms (continued)
SITE Superfund Innovative Technology Evaluation
SPEW spiked purged effluent water
TCE trichloroethene
trans-1,2-DCE trans-1,2-dichloroethene
TT treatment train
UV ultraviolet
VC vinyl chloride
VOA volatile organic analysis
VOC volatile organic compound
xii
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Acknowledgments
We wish to acknowledge the support of all of those who helped plan and conduct this demonstration,
interpret the data, and prepare this evaluation report. In particular, for demonstration site access and
relevant background information, Barbara Newman, Wells Q and H Remedial Project Manager (EPA
Region I); for on-site coordination, Jeffrey Lawson (Environmental Project Control, Inc.); for QA oversight
and support for the performance evaluation study, Elizabeth Schultz (Trillium, Inc.); for the preliminary
evaluation and QA plan, James Smith (Trillium, Inc.); for preparation of the Demonstration Plan, Deb
Chaloud (Lockheed); for field sampling and logistics, Kevin Cabbie (Lockheed); for project management,
Scott Hulse (Lockheed) and Deirdre O'Leary (Lockheed); for EPA project management, Eric Koglin and
Stephen Billets (EPA); for project management of the EPA/University of Houston Cooperative Agreement,
John Nocerino (EPA); for data review, Grade Martucci (Lockheed); for data reduction, John Zimmerman
and Bryant Hess (Lockheed); and for word processing support, Julia Jackson, Lillian Steele, Pat Craig,
and Jan Aoyama (Lockheed). In addition, we gratefully acknowledge the comments and suggestions of
those who reviewed this report Reviewers included Alan Crockett (EG&G Idaho, Inc.), Christian Daughton
(EPA), Mitchell Erickson (Argonne National Laboratory), Jeff RosenfekJ and Mark Silverstein (Lockheed),
and Kaveh Zarrabi (University of Nevada, Las Vegas).
xiii
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Executive Summary
An automated system designed to monitor volatile organic compounds (VOCs) in a water-treatment pro-
cess stream was evaluated under the U.S. Environmental Protection Agency (EPA) Superfund Innovative
Technology Evaluation (SITE) Program. The monitoring system evaluated was the Analytic and Remedial
Technology, Inc., Volatile Organic Analysis System (AVOAS). The AVOAS permits unattended sampling
from multiple locations, with extraction of VOCs from the samples by a proprietary process similar to purge
and trap, and analysis by gas chromatography (GC).
The demonstration was conducted under the guidance of the EPA Environmental Monitoring Systems Lab-
oratory in Las Vegas, Nevada (EMSL-LV), as part of the Monitoring and Measurement Technologies por-
tion of the SITE Program. A mandate of the SITE Program is to identify cost-effective alternatives to
existing methods used in characterizing and remediating contamination at Superfund sites. SITE demon-
strations provide a mechanism for evaluating selected technologies that are at least comparable in quality
and cost to established methods.
Currently, most methods for processing samples used to monitor remediation at Superfund sites require a
number of steps. These include sample collection, preservation, transport, storage, and analysis at off-site
laboratories. The principal drawbacks to these procedures are the need for trained sampling personnel,
the turnaround time for results, the cost per analysis, and, particularly for VOCs, the potential for changes
in sample integrity between the time of sample collection and analysis. The proposed advantages of the
AVOAS are that it replaces conventional sampling and analysis procedures and provides results within
less than an hour of sampling (i.e., nearly real-time results). Further, the AVOAS continuously monitors the
function of the various components of a treatment system, permitting process control capability. Malfunc-
tions in a treatment system can be quickly detected as increased concentrations of VOCs, signalling the
need for maintenance or other measures to correct the problem.
For the application evaluated in this demonstration, the AVOAS was incorporated as a dedicated compo-
nent of a treatment system being tested at an EPA Region I Superfund site for remediating ground water
contaminated with chlorinated VOCs. The treatment system was a series of discrete units designed to
progressively reduce contaminant concentrations. The AVOAS measured VOC concentrations after each
treatment unit.
The demonstration compared the performance of the AVOAS with that of EPA Method 502.2. The field
portion of the demonstration was conducted May 18 through 24, 1991, at the Wells G and H Superfund
Site in Wobum, MA. For the demonstration, the ground-water treatment system was operational, and
samples were collected and analyzed in the monitoring mode for which the AVOAS was designed. Sam-
ples were also collected using standard methods for VOCs in water, and were analyzed by the AVOAS
operated in the "off-line" mode and by Method 502.2 at the EMSL laboratory in Las Vegas, NV. In addition
to samples from the treatment system, samples spiked with measured concentrations of analytes and a
variety of quality assurance and quality control (QA/QC) samples were analyzed by each method.
A total of 96 samples analyzed by the AVOAS and the EMSL-LV instrument during the demonstration were
used to assess the performance of the AVOAS. The AVOAS ran an average of 22.3 hours per day, which
included approximately 8 hours per day of unattended operation. Only minor breakdowns occurred, and
recalibration and maintenance requirements were minimal. The qualitative and quantitative findings gen-
erated in this demonstration provided the basis for the following observations about the performance of the
AVOAS:
xv
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1) Concentration values generated by the AVOAS for virtually all samples were higher than those mea-
sured by Method 502.2; however, AVOAS analyte recovery values were closer to 100%. The cause of
this finding cannot be resolved from the data available from this short-term study. The precision
obtained by the AVOAS was comparable to that obtained by Method 502.2, and was within the expected
range.
2) The AVOAS performed well in analyzing samples with VOC concentrations in the low-ppb to low-ppm
range.
3) The proprietary system used by the AVOAS for stripping VOCs from water is simple in design and func-
tion and more adaptable to field automation than the traditional purge-and-trap procedure.
4) The demonstration showed that the AVOAS is capable of providing the benefits of automated sampling
and analysis, as proposed. That is, it provides real-time results and eliminates manual sample collec-
tion, handling, shipping, and analysis steps as well as the potential for losses in sample integrity. In
addition, the potential cost savings for use of the AVOAS in comparison to use of established methods
could be substantial, particularly for processing large numbers of samples (i.e., for long-term, continu-
ous monitoring).
The following items were identified as potential limitations to the use of the AVOAS. Many of these are not
so much limitations, as factors that must be kept in mind or planned for by prospective users of the
AVOAS. The AVOAS developer recognized some of these limitations during the demonstration, and has
since taken steps to correct equipment or procedures.
1) The AVOAS requires a temperature-controlled environment and an atmosphere free of contamination.
Although maintaining these conditions was not a problem at the location where this demonstration was
conducted, extra measures to ensure these conditions may be required in other field situations or indus-
trial facilities.
2) Water samples high in paniculate matter tend to clog a filter in the injector inlet. The impact of this prob-
lem can be minimized if water is pre-filtered before being conveyed to the AVOAS. Also, cleaning and
replacement of the filter can be incorporated as part of the routine maintenance procedures.
3) The possibility of carryover in the smallest sample loop of the AVOAS was suggested by the finding of
an increase in trace concentrations of several analytes in ground-water treatment system (i.e., treat-
ment train) samples between morning and afternoon analyses. The AVOAS developer has modified the
design of the manifold to reduce dead volume significantly, and expects this change to greatly reduce
the carryover problem.
4) Many of the (relatively minor) problems encountered with the AVOAS during the field demonstration
were due to problems in the system software, most of which were corrected during the demonstration.
Based on the findings of this study, the following recommendations are made:
1) Further development of the AVOAS is encouraged, and additional studies should be performed. Perfor-
mance data should be generated for this system when used at other sites, by different operators, and in
the fully automated mode.
2) Instrument calibration should be checked regularly on a schedule based on the performance of the
detector. A daily calibration check is recommended. If this is not feasible, at a minimum, detector per-
formance should be monitored daily over a period of several weeks after instrument installation. An
appropriate calibration schedule should be developed and followed for the long-term use of the system.
especially for unattended, remote operation.
3) A mechanism for introducing surrogate standards into the AVOAS with each analysis would provide an
ongoing indication of analytical instrument performance.
4) Depending on the data quality objectives for instrument performance at a particular site, blank samples
should be periodically analyzed on all sampling loops, to ensure that carryover from high-concentration
samples into low-concentration samples is not occurring.
5) During the initial stages of long-term monitoring, concentrations for each sampling port, as well as data
on instrument precision should be closely monitored to generate expected baseline conditions. Periodic
confirmatory analyses by established methods should be perfoomed to verify instrument results.
xvi
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Section 1
Introduction
The Analytic and Remedial Technology, Inc.,
Volatile Organic Analysis System (AVOAS) was
evaluated under the U.S. Environmental Protection
Agency (EPA) Superfund Innovative Technology
Evaluation (SITE) Program. The AVOAS is
designed to monitor volatile organic compounds
(VOCs) in water-treatment process streams. The
system provides automated sampling from multi-
ple locations, with extraction of VOCs from the
samples by a proprietary process similar to purge
and trap, and analysis by gas chromatography
(GQ. The purpose of the demonstration described
in this report was to compare the performance of
the AVOAS with that of an established method.
This section provides an overview of the
SITE Program and descriptions of the AVOAS, the
site of the demonstration, and the project organiza-
tion. The rest of the report is organized into four
sections. Section 2 describes the AVOAS demon-
stration; Section 3 presents and discusses the quan-
titative and qualitative results of the evaluation;
and Section 4 presents the conclusions and recom-
mendations based on the findings of the demon-
stration.
SITE Program Background
The Superfund Program was initiated in 1980
to identify, prioritize, and remediate uncontrolled
hazardous waste sites. Subsequently, the problems
associated with hazardous waste sites proved to be
far more complex man originally anticipated. In
1986, the U.S. Congress enacted the Superfund
Amendments and Reauthorization Act (SARA),
requiring the EPA to promote more effective haz-
ardous waste site identification and cleanup. The
SITE Program addresses Section 311(b) of SARA,
which requires the EPA to establish "a program of
research, evaluation, testing, development, and
demonstration of alternative or innovative treat-
ment technologies...which may be utilized in
response actions to achieve more permanent pro-
tection of human health and welfare and the envi-
ronment"
Two categories of technologies are addressed
under the SITE Program: (1) treatment technolo-
gies that may serve as alternatives to land disposal,
and (2) technologies for measuring and monitoring
contaminants at hazardous waste sites. This latter.
portion of the SITE Program is administered by the
Advanced Field Monitoring Methods Program
(AFMMP). The Environmental Monitoring Sys-
tems Laboratory at Las Vegas, Nevada (EMSL-LV)
is the lead laboratory for the AFMMP, and pro-
vided oversight of the demonstration described in
this report
AVOAS Technology Description
The AVOAS was designed by Gary Hopkins
and Doug Mackay of Analytic and Remedial Tech-
nology, Inc. (ATO, Inc., Menlo Park, CA). The
AVOAS consists of a sampling manifold and a
purge-and-trap concentrator ("injector") con-
nected to a gas chromatograph (GQ. An integrator
processes the GC signal data, and a computer is
used to control the system and to store the data.
The innovative components are the sampling mani-
fold, the injector, and the computer software. The
manifold permits on-line collection of samples
from multiple locations. The injector collects a
measured volume of water, strips the VOCs from
the aqueous to the gas phase, traps them on a sor-
bent, and thermally desorbs them into the GC. The
computer software handles data storage and con-
trols the analytical system. With use of a modem,
data can be transmitted off-site, allowing remote
operation and control of the AVOAS, eliminating
the need for the physical presence of the operator
at the site. Figure 1-1 is a schematic of the
AVOAS.
Among the features that can be controlled are
the sampling sequence (i.e., the order in which the
manifold valves are actuated); the flush time for
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the sampling lines; the sample size; and the inte-
grator operating parameters. Sample size is con-
trolled via a switching valve, which permits
selection among sample loops of different internal
volumes. To optimize detection of target analytes,
the sample volume can be selected based on either
prior knowledge of potential concentration ranges
at a given sampling point or by computer logic. In
the computer logic mode, the microcomputer is
programmed to repeat a sample analysis using a
different loop volume if the first measurement is
out of the range of instrument detection or calibra-
tion. Sample sizes fromlOO jiL (the dead volume
of the valve) to 10 mL or more are possible (the
upper limiting volume is defined by the maximum
sample processing time required for any applica-
tion). The sampling loops are flushed with VOC-
free water between samples. To minimize sample
carryover (i.e., adsorption of compounds in sam-
ples to analytical surfaces they contact, followed
by desorption into subsequent samples), the mani-
fold and all sample loops and sample conveyance
lines are constructed of stainless steel. External
samples, including calibration standards and qual-
ity control (QQ samples, are introduced into the
system through a line between the manifold and
injector. Water samples from each sample port can
be collected at the manifold for off-site, confirma-
tory laboratory analysis. The AVOAS can be used
with virtually any GC and integrator, and can be
adapted to different purgeable analytes by selection
of the appropriate GC column, temperature pro-
gram, and detector. Earlier versions of the system
have been used in site-specific research applica-
tions. The version evaluated in this demonstration
had modifications intended to make the AVOAS a
commercially marketable product
For the application discussed in this report,
the AVOAS functioned as a dedicated component
of a treatment system being demonstrated at a
Superfund site to remediate ground water contami-
nated with chlorinated VOCs. The treatment sys-
tem consisted of a series of discrete units designed
to provide a stepwise reduction in contaminant
concentrations. The AVOAS measured VOC con-
centrations at selected locations in the ground-
water treatment system.
AVOAS Demonstration Overview
Purpose of the AVOAS Demonstration
The purpose of this demonstration was to
compare the performance of the AVOAS while
operating at the site of a remediation with that of
an established method conducted in a fixed-base
laboratory. EPA Method 502.2, "Volatile Organic
Compounds in Water by Purge and Trap Capillary
Column Gas Chromatography with Photoioniza-
tion and Electrolytic Conductivity Detectors in
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Series - Revision 2," was selected for comparison,
because operation of the AVOAS most closely fol-
lows the specifications of that method. This SITE
demonstration was not intended to evaluate the
ground-water treatment system.
The primary goal of the demonstration was to
generate data of sufficient quality, quantity, and
type, by both the AVOAS and the comparison
method, to permit a sound interpretation of results.
A demonstration plan prepared prior to the AVOAS
evaluation identified the specific study objectives
and described in detail the sampling, analysis, and
QA/QC activities required to meet those objec-
tives.
Qualitative measures of system performance
(ruggedness, reliability, maintenance requirements,
facility and supply requirements, and cost) were
not specifically defined in the AVOAS Demonstra-
tion Plan; however, these measures were infor-
mally evaluated and are discussed in this report.
Performance characteristics such as specificity and
interferences, which are determined by the detec-
tion system (i.e., the chromatographic column, gas
chromatograph, and detector), were not considered
in this demonstration because these characteristics
are not a function of the innovative components of
the AVOAS.
Demonstration Site Description
The AVOAS demonstration was performed at
the Wells G and H Superfund Site in Woburn, Mas-
sachusetts. The site covers 330 acres and includes
the aquifer and land in the vicinity of two former
municipal drinking water wells (Wells G and H).
Figure 1-2 is an area map of the site.
Wells G and H had been used as a source of
municipal water until, in 1979, the Massachusetts
Department of Environmental Protection detected
contamination by chlorinated VOCs in water sam-
ples from the wells. The primary contaminants
include trichloroethene (TCE) and tetrachloroet-
hene (PCE), with lesser amounts of 1,1-dichloroet-
hene (1,1-DCE), cis-l,2-dichloroethene (cis-1,2-
DCE), trans-l^-dichloroethene (trans- 1,2-DCE),
1,1-dichloroethane (1,1-DCA), and 1,1,1-trichloro-
ethane (1,1,1-TCA). In December 1982, the EPA
put the site on the National Priority List, and in
September 1989, a Record of Decision was issued
requiring that the ground water beneath the site be
treated to remove the contamination.
A pilot demonstration (conducted under a dif-
ferent program) of a ground-water treatment sys-
tem installed in the Unifirst Facility presented the
opportunity to simultaneously evaluate the perfor-
mance of the AVOAS. The treatment system pilot
demonstration was May 18 through May 30,1991,
and the field portion of the AVOAS SITE demon-
stration was conducted over the 6-day period of
May 18 through 24. During the pilot demonstra-
tion, the treatment process included units for ultra-
violet/chemical oxidation, carbon adsorption, and
reductive dehalogenation. Figure 1-3 is a sche-
matic of the ground-water treatment system. Sam-
pling ports at selected locations permitted
monitoring the concentration of VOCs before and
after each treatment step. The sampling ports used
to evaluate the AVOAS included port S-3 (after the
carbon drum, before the oxidation unit) and port S-
4 (after the reductive dehalogenation unit, before
the oxidation unit). Sample collection from two
ports was specified in the Demonstration Plan, on
the expectation that differences in concentration
would provide information about the performance
of the AVOAS in measuring more than one concen-
tration. Samples from each port were analyzed
separately; i.e., samples from S-3 and S-4 were not
physically combined. Water from port S-6 (treated
effluent) was used to prepare spiked samples and
analytical and transport blanks.
Project Organization
The EMSL-LV and its prime contractor,
Lockheed Engineering & Sciences Company
(LESQ, worked together to plan, conduct, evalu-
ate, and report the results of the AVOAS demon-
stration. The EMSL-LV Technical Leader
arranged scheduling and the approach of the dem-
onstration. The Technical Leader was also respon-
sible for communicating with EPA Region I staff to
obtain access to the site, and for background and
health and safety information. Oversight of all
remedial activities at the Wells G and H Superfund
Site is the responsibility of the EPA Region I
Remedial Project Manager. The site remediation
contractor for the potentially responsible parties is
Environmental Project Control, Inc. (EPQ. For
the AVOAS demonstration, ETC was responsible
for overseeing or conducting all of the operational
aspects of the ground-water pump-and-treat pro-
cess. The Johnson Company designed the treat-
ment system. EPC arranged the subcontract with
A*RT, Inc. to provide the on-line analytical capa-
bility.
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MASSACHUSETTS
Ground-Water
Extraction Well
Location of the
Ground-Water
Treatment System
andtheAVOAS
Unifirst
Facility
Golden
School
OAD1047GR92
Figure 1-2. Area map of the Wells G and H Superfund Site, Woburn, Massachusetts.
-------
voc
CONTAMINATED
INFLUENT FROM
GROUND-WATER
EXTRACTION WELL
VOC-FREE
EFFLUENT
(TO STORM
SEWER)
SAMPLE LINES FROM
TREATMENT TRAIN
SAMPLE PORTS "
SAFETY/
DECONTAMINATION AREA
MULTI-MEDIA/
PRESSURE '
FILTER
REDUCTIVE /
DEHALOGENATION
UNIT
A RT, INC.
VOLATILE ORGANIC
ANALYSIS SYSTEM
0123
I I I I
SCALE IN FEET
LEGEND
SAMPLING
PORT
GATEVALVE
Sample Pa
S-1
S-2
S-3
S-4
S-5
S-6
a
Influent from ground- water extraction well
After reductive denaJpaenatfon unit
After carbon drum, bei
Betoreoxidationunlt
After oxidation wit
Treated effluent
yecoddatian unit
Rgure 1-3. Schematic of the UnMrat Ground-Water Treatment System.
-------
Figure 1-4 shows the organizational structure
for the AVOAS demonstration. Key participants
included:
Statistician (LESC): Responsible for designing
the evaluation and overseeing data analysis and
interpretation of results, including verifying and
validating data, generating data tables and plots,
and programming and executing statistical rou-
tines.
Demonstration Design Consultant (EPA Cooper-
ative Agreement, University of Houston):
Assisted in the development of the AVOAS dem-
1
EPA/Region I
Wells G and H Superfund Site
Remedial Project Manager
Region I
Site Contractor
(EPC)
Treatment
System Design
(Johnson Co.)
Treatment System
Monitoring
(A+RT,Inc.)
EPA/EMSL-LV
Monitoring and Measurement
Technologies Program
AVOAS Demonstration Project Oversight
Ground-water
Treatment System
(Unifirst)
Demonstration
and QA Plans
Field Logistics/
Safety and Health
EPA Method
502.2 Analyses
Database
Management
Data
Interpretation
EMSL-LV Environmental Monitoring Systems Laboratory-Las Vegas
LESC - Lockheed Engineering & Sciences Company
QA - Quality Assurance
SITE - Superfund Innovative Technology Evaluation
A+ RT, Inc. Analytic and Remedial Technology, Inc.
EPC - Environmental Project Control, Inc.
Figure 1-4. Organizational Structure of the AVOAS Demonstration.
-------
onstration design. Provided data interpretation
and report review.
Supervising Chemist (LESC): Responsible for
ensuring the technical and scientific quality of
the project Responsible for overseeing or per-
forming technical activities related to planning
and conducting the evaluation and interpreting
results, including overseeing field and reference
laboratory operations, preparing sample spikes,
and approving any modifications to the Demon-
stration Plan.
AVOAS Developer (A+RT, Inc.): Responsible
for installing and operating the AVOAS at the
field site, including calibrating the instrument,
collecting treatment train samples, analyzing
samples, and providing copies of the data gener-
ated by the AVOAS.
Project QA Manager (LESC): Responsible for
developing the QAPjP and for overseeing the
review and interpretation of the QA data.
Logistics and Sampling Coordinator (LESC):
Responsible for all aspects of field operations,
including site reconnaissance, sample collection
and shipment, sample chain-of-custody, decon-
tamination of equipment and disposal of hazard-
ous wastes in the field, and documentation of
field activities.
Laboratory Analyst (LESC): Responsible for
analyzing samples in accordance with EPA
Method S02.2 and with the Demonstration Plan
and the QAPjP, and for documenting and report-
ing data in the required format.
Data Base Manager (LESC): Responsible for the
acquisition and formatting of all data generated.
Health and Safety Coordinator (LESQ: Respon-
sible for ensuring that all field and laboratory
health and safety issues were addressed, and for
preparation and approval of the Site Safety and
Health Plan.
Report Coordinator and Writer (LESQ: Respon-
sible for coordinating input from project partici-
pants and preparing this report
-------
Section 2
AVOAS Demonstration Design and Activities
Demonstration Design
Rationale Behind the AVOAS
Demonstration Design
An important objective of the AVOAS dem-
onstration design was to account for factors that
could affect the comparability 'of results. These
included: 1) sample-related factors, including sam-
ple matrix effects and changes in sample integrity
during collection, preservation, transport, and stor-
age and 2) variability due to analysis, including
differences in instrument hardware and function,
day-to-day variation in operating conditions, drift
in instrument calibration, and variability in the lab-
oratory technique of different analysts.
Sources of Variability in Samples
Sample Matrix Effects Chromatographic
retention times and measured concentrations of tar-
get analytes can be .affected by the chemical and
physical characteristics of the sample, i.e., the sam-
ple matrix. Matrices in this demonstration
included 1) reagent-grade water for malting the
standards for the initial calibration and for the daily
instrument calibration checks and 2) ground-water
treatment system (i.e., treatment train) water. To
reduce the potential variability due to matrix, treat-
ment train effluent water from port S-6 was purged
to remove VOCs and was used for travel blanks,
AVOAS instrument blanks, and for preparing
spiked samples.
Changes in Sample Integrity Sample
integrity refers to how well the sample composi-
tion and concentration at the time of. analysis
reflect those characteristics at the time the sample
was collected. For demonstrations in which two
methods are being compared, maintaining unifor-
mity in the sample pairs analyzed by the test and
the comparison method is critical for comparing
data from both methods. Sample integrity can be
compromised by collection procedures, sample
container characteristics, conditions during ship-
ping (e.g., temperature or barometric pressure
changes), component degradation or alteration
(e.g., due to biological or photochemical pro-
cesses), and handling steps during analysis. Main-
taining the integrity of samples containing low-
molecular-weight chlorinated hydrocarbons, the
target analytes for the AVOAS demonstration, is a
particular challenge because those compounds can
easily volatilize into the atmosphere or sorb to con-
tainer materials. In addition, residues in sample
containers or in the atmosphere in which the sam-
ples are stored can contaminate samples, leading to
biased or false-positive results (e.g., increased con-
centrations or the presence of compounds not actu-
ally present in the medium sampled).
The potential for changes in sample integrity
was a concern for samples shipped to EMSL-LV,
because they required additional handling steps
and time between sampling and analysis. To mini-
mize variability, the guidelines of Method 502.2
for collecting, preserving, shipping, and handling
samples containing VOCs were followed. In addi-
tion, holding time the time between sample col-
lection and analysis was minimized as much as
possible. A transport study was performed in
which results for samples spiked with known ana-
lyte concentrations and shipped, were compared
with results for corresponding samples not
shipped.
Sources of Analytical Variability
Differences in Instrument Hardware and
Operation The manner in which the AVOAS
collects and handles samples when operated in the
automated ("on-line" mode) did not permit direct
comparison of sample results with those of Method
502.2. In the on-line mode, the AVOAS conveys
samples from the sampling ports to the analytical
system. Samples are introduced directly into the
injector without exposure to the atmosphere, and
are analyzed immediately. In contrast, the estab-
-------
lished methods, including Method 502.2 involve
manual collection of samples into containers,
transport to a laboratory, and refrigerated storage
prior to analysis. The sample is exposed to the
atmosphere during collection, and usually again
just before analysis. To help identify any effects on
the data due to these inherent differences in proce-
dure, the AVOAS was used in both the on-line,
automated mode and in off-line mode for analysis
of treatment train samples. For the off-line proce-
dure, the line between the manifold and injector
was momentarily opened and placed in the sample
vial. The sample water was then pumped through
the sampling loop of the AVOAS injector.
Another difference between the AVOAS and
typical Method 502.2 analyses is the means by
which sample concentrations are adjusted to fall
within the linear range of the detector. The
AVOAS injector uses sampling loops of different
volumes that can be selected to adjust for analyte
concentrations. For example, for high-concentra-
tion samples, a small sample volume is used so that
a small quantity of analyte is introduced into the
analytical system. By contrast, the standard purge-
and-trap apparatus used with the EMSL-LV instru-
ment makes all injections using the same sample
volume. Adjustments to keep the sample concen-
tration range within the linear range of the detector
are made by diluting the sample. For this demon-
stration, sample dilution was required to bring the
highest concentration analyte, PCE, to within the
linear range of the EMSL-LV detector. Potential
sources of variability in the EMSL-LV data arise
from the dilution procedure, and for the AVOAS
data, from the performance of the sampling loops.
Finally, the method by which the AVOAS
strips VOCs from samples (A*RT, Inc. proprietary)
is different from standard purge-and-trap tech-
niques, so that differences in VOC stripping effi-
ciency are possible. Although this difference
should be compensated for through analysis of
standards, stripping efficiency for the different
sample loop sizes may vary; this source of variabil-
ity was not evaluated in this demonstration.
Day-to-Day Variations in Instrument Operat-
ing Conditions Day-to-day variability in instru-
ment operating conditions could arise from several
sources. The GC used in this demonstration with
the AVOAS is very basic in design. It was installed
on location at the industrial facility where the
ground-water treatment system is housed. The
demonstration began within 3 days after the
AVOAS was installed. During the demonstration.
in addition to processing SITE demonstration sam-
ples, the AVOAS was used in the on-line monitor-
ing mode and for off-line analyses of samples from
a second treatment system. The AVOAS was oper-
ating for over 22 hours per day during the demon-
stration. Samples of widely varying concentrations
were analyzed sequentially, providing the potential
for contaminant carryover from high-concentration
samples. In contrast, the EMSL-LV instrument
had been allowed to stabilize in the laboratory for
nearly 2 weeks prior to the demonstration. Only
AVOAS demonstration samples were analyzed by
that instrument during this study, and the instru-
ment was used less than 8 hours per day.
To help detect day-to-day sources of variabil-
ity, quality control check standards, continuing cal-
ibration check standards, and instrument blanks
were analyzed daily. To identify effects due to the
time of day, treatment train samples were collected
and analyzed by the AVOAS in both the morning
and the afternoon.
Drift in Instrument Calibration Changes
in instrument response factors or calibration curves
can be a significant source of measurement vari-
ability in VOC analysis. Both the AVOAS and
EMSL-LV instruments were calibrated prior to the
demonstration, and their calibration was monitored
daily using the CCCS.
Other Sources of Variability Data for
spiked samples can have inherent variability. For
example, analyst spiking technique can vary, and
actual concentrations of spiking solutions can be
different from intended concentrations. To mini-
mize these sources of variability, the stock solu-
tions for spiked samples were prepared in batches
and sealed in ampoules by one chemist before the
study. Spiked samples and sample aliquots were
prepared by the same chemist at die field site.
AVOAS Demonstration Evaluations
The assessment of the AVOAS performance
relative to that of Method S02.2 was based on three
evaluations, which are depicted schematically in
Figure 2-1 and are described below.
1. The true concentrations of VOCs in the ground-
water treatment train water were unknown.
Therefore, to assess the comparability of results
obtained by the AVOAS and by Method 502.2,
samples spiked with known concentrations of
analytes (i.e., spiked purged effluent water sam-
ples) were prepared at the field site and were
analyzed by both instruments. Data were gener-
10
-------
1) SPIKED PURGED
EFFLUENT WATER SAMPLES
(Prepared at the field site in
WobunuMA)
-» AVOrtS Off-line analysis
2) TREATMENT TRAIN SAMPLES
(From ground-water treatment system
at the field site in Wobura. MA)
3) TRANSPORT STUDY SAMPLES
(Piepated and analyzed in Las Vegas, NV)
L- low-concentration spiked sample
M. medium
-------
TABLE 2-1. SAMPLE TYPES ANALYZED FOR THE AVOAS DEMONSTRATION
Simple Name
Sample Description
Use
Purpose
Purged Effluent Water
(PEW)
Spiked Purged
Effluent Water
(SPEW)
Treatment Train (TT)
Quality Control Check
Standard (QCCS)
Continuing
Calibration Check
Standard (CCCS)
Water from treatment train sample port
S-6, purged to remove VOCs
Purged effluent water spiked with nine
compounds in four concentration
ranges; analyzed by the AVOAS (off-
line) and EMSL-LV. SPEW samples
were made in the field from ampoules
of stock solutions prepared prior to the
demonstration.
Samples from treatment train ports S-3
and S-4, analyzed by the AVOAS (on-
line and off-line) and EMSL-LV.
QC standard required by EPA Method
502.2 containing 5 VOCs at low and
very low u,g/L levels, analyzed by both
the AVOAS and EMSL-LV.
A calibration check standard analyzed
daily by both the AVOAS and EMSL-
LV.
For making up matrix spike samples for
analysis by the AVOAS and by EMSL-
LV.
As a blank sample for the AVOAS and as
a travel blank for samples shipped to
EMSL-LV.
For making up matrix spike samples
analyzed by EMSL-LV for the transport
study.
To compare the accuracy and precision
obtained by the AVOAS (off-line) and by
EMSL-LV.
In the transport study, to compare results
between transported and non-
transported samples.
To determine whether AVOAS off-line
results are representative of AVOAS
on-line results
To compare AVOAS and EMSL-LV
measurement performance
To indicate any loss of instrument
sensitivity.
To verify instrument performance in
terms of response factors.
To minimize variability due
to matrix effects of the
treatment train water.
To provide samples of
known concentration in a
variety of concentration
ranges.
To provide actual
environmental samples.
To provide samples of
known concentration so
that instrument
performance can be
monitored.
To provide samples of
known concentration so
that ongoing instrument
performance can be
monitored.
Treatment Train Samples
The protocol for collection of treatment train
(TT) samples was as follows: Each morning dur-
ing the routine AVOAS on-line collection and anal-
ysis of a sample from port S-3 or S-4, water from
the port sampled AVOAS was also collected auto-
matically into four 40-mL volatile organic analysis
(VOA) vials. The first vial collected was analyzed
by the AVOAS immediately after the on-line analy-
sis of the same sample, using the off-line proce-
dure. The TT samples for EMSL-LV were
preserved by acidifying to pH<2 with HC1. In the
afternoon, the alternate port (S-3 or S-4) was sam-
pled in the same fashion. Both morning and after-
noon TT samples were shipped that day to EMSL-
LV by overnight express carrier.
Purged Effluent Water
Purged effluent water (PEW) was prepared as
follows: Four gallons of water from sampling port
S-6 (final effluent) was collected into a 5-gallon
Pyrex solution bottle on May 16 and was purged
continuously using high-purity helium gas. The
purged water was poured into four 1-L bottles and
was analyzed in the field using the AVOAS instru-
ment to verify the absence of VOCs. Three 1-L
bottles of the purged water were sent to EMSL-LV
for use in the transport study. The remaining liter
12
-------
TABLE 2-2. SUMMARY OF ANALYTE CONCENTRATIONS (ng/L), BY SAMPLE TYPE
Treatment
Train1
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
Port
S-3
NO
6.7
0.68C
3.6C
19
37
ND
75
2583
Port
S-4
NO
5.9
0.82C
3.0C
13
31
ND
60
2550
Spiked Purged Effluent Water"
Low
22.4
4.6
13.8
9.1
28.1
9.1
9.0
213
23.7
Medium
37.4
91.1
97.5
45.6
23.7
91.1
39.2
53.8
88.7
High
224
45.6
138
91.1
281
91.1
90.2
213
237
Super
High
747
0
1946
911
467
1822
788
1067
1774
QCCS"
EMSL-
LVand
AVOAS
20.0
2.0
0
0
0
10.0
20
2.0
15.0
cccs"
EMSL-
LV
20
20
20
20
20
20
400
20
20
AVOAS
400
400
400
400
400
400
400
400
400
Transport Study6
Medium
37.4
91.1
97.5
45.6
23.7
91.1
39.2
53.8
88.7
High
227
45.6
138
91.1
281
91.1
90.2
213
237
NO: Not detected by either the AVOAS or EUSL-LV.
CCCS: Continuing calibration check standard.
QCCS: Quality control check standard.
' Mean concentration. ng/L. Values are approximate and are mean values for all samples collected (a.m. and p.m.) by the AVOAS over the 6-day
demonstration.
11 Target concentration, fig/L
e Detected by AVOAS, but not by EUSL-LV.
was used to prepare the spiked samples and was
also used as an instrument blank for the AVOAS.
Spiked Purged Effluent Water
Spiked purged effluent water (SPEW) sam-
ples were freshly prepared each day of the demon-
stration at the field site. The solutions used to
spike the PEW had been prepared for each of four
spiking concentration ranges and sealed in glass
ampoules at EMSL-LV prior to the field demon-
stration. New ampoules were opened daily to pre-
pare SPEW samples, and the spiking procedure
was performed by the same chemist to minimize
variability due to spiking technique. To prepare
each SPEW sample, a 40-mL VGA vial was filled
most of the way with PEW. The spiking solution
was added directly into the VOA vial using a
micropipette. Purged effluent water was added to
fill the vial, and the vial was capped immediately
and checked for bubbles. If bubbles were present,
the vial was discarded, and a fresh spiked sample
was prepared.
Duplicate spike-sample vials were made from
the same ampoule. One sample vial of each con-
centration range was analyzed by the AVOAS in
the off-line mode, generally within 1 hour of prep-
aration. The other aliquots were preserved (acidi-
fied with HC1 to pH<2), chilled at 4 °C. and
shipped to EMSL-LV in coolers. The aliquot ana-
lyzed in the field was not preserved.
To help maintain analyst objectivity, neither
the AVOAS nor the EMSL-LV analysts were
informed beforehand of the exact SPEW spiked
concentrations.
Performance Evaluation Study
A performance evaluation (PE) study was
conducted prior to the demonstration on behalf of
EPC, Inc. by Trillium, Inc. The PE study had two
objectives: 1) the determination of method detec-
tion limits (MDLs) and practical quantitation limits
(PQLs) for both the EMSL-LV and A+RT, Inc.
instruments for each of the nine analytes targeted
for the AVOAS demonstration and 2) the analysis
of "blind" (i.e., the composition and concentration
13
-------
are unknown to the analyst) samples, to provide an
impartial determination of instrument performance
in measuring low (ppb level) concentrations of
analytes. EMSL-LV analyses were performed
using modified EPA Method 502.2 procedures.
For the AVOAS analyses, the PE samples were
introduced in the sample manifold in the off-line
mode. At the time of the PE study, the AVOAS
was not yet installed at the field site, so the PE
samples were analyzed at the A^RT, Inc. research
and development facility.
Determination of Method Detection and
Practical Quantitation Limits
The MDL of a method is defined as its perfor-
mance in measuring an analyte in a sample matrix,
regardless of the sample's origin (Closer et al.,
1981). For the PE study, the MDL was set as three
times the standard deviation of the analytical
results for seven replicate analyses, in |ig/L. The
PQL was set as 10 times the MDL.
A representative ground-water sample was
used by each laboratory to make spiked samples
for the MDL and PQL determinations. The spiking
concentration of each analyte was 1 fig/L. Seven
replicates each of spiked and unspiked aliquots
were analyzed alternately, and the MDLs and
PQLs were calculated for each compound. Table
2-3 gives the EMSL-LV and A+RT, Inc. MDLs for
each sample type analyzed for the demonstration.
The MDLs for the AVOAS depended on sample
volume, as determined by sample loop size. In the
Trillium, Inc. study, the 10.0-mL sample loop was
used on the AVOAS, and MDLs were calculated
for the other loop volumes. The MDLs for the
EMSL-LV instrument depended on the dilution
factor used.
TABLE 2-3. SUMMARY OF METHOD DETECTION LIMITS ftig/L) FOR THE AVOAS AND EMSL-LV
INSTRUMENTS, BY SAMPLE LOOP SIZE, DILUTION, AND SAMPLE TYPE
Compound
AVOAS1
EMSL-LV
10-rnL
Loop
5-fflL
Loop
1.0-mL
Loop
0.2-mL
Loop
No
Dilution
1:10
Dilution
B, L II.QCCS H S,TT
Samples Simple* Samplai Samplai
1:100
Dilution
B,L,M,
QCCS H S,TT
Samples Samples Samples
vinyl chloride
1,1-dichloroethene
trans-1 ,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroettiene
tetrachloroethene
0.08
0.05
0.01
0.02
0.02
0.07
0.05
0.03
0.01
0.16
0.1
0.02
0.04
0.04
0.14
0.10
0.06
0.02
0.8
0.5
0.1
0.2
0.2
0.7
0.5
0.3
0.1
4.0
2.5
0.5
1.0
1.0
3.5
2.5
1.5
0.5
0.08
0.16
0.17
0.08
0.24
0.12
0.19
0.22
0.3
0.8
1.6
1.7
0.8
2.4
1.2
1.9
2.2
3.0
8.0
6.0
17
8.0
6.0
23
19
22
30
1 Method Detection Limits (MDLs) were measured using the 10-mL loop; MDLs for the other loop sizes wen calculated from those values.
For the demonstration, each sample type was analyzed using the loop or dilution indicated in the table headings:
B: Blank
L: Low-concentration spiked purged effluent water sample.
M: Medium-concentration spiked purged effluent water sample.
H: High-concentration spiked purged effluent water sample.
S: Superhigh-concentration spiked purged effluent water sample.
QCCS: Quality control check standard.
77: Treatment tram sample.
14
-------
Analysis of Blind Performance Evaluation
Samples
Two PE samples were sent to each of the par-
ticipating laboratories by Trillium, Inc. Each of the
two samples was provided in three 40-mL vials
and a 1-L bottle. The compounds in one of the
samples were present at concentrations of approxi-
mately 1.7 to 2.5 (Ag/L, and in the other at approxi-
mately 0.1 to 0.6 |ag/L. Trillium, Inc. determined
that the EMSL-LV and AVOAS results were com-
parable.
Transport Study
The effect of shipping on sample integrity
was supposed to be studied concurrently with the
AVOAS demonstration, using the AVOAS to ana-
lyze transported and nontransported samples.
However, scheduling commitments for the AVOAS
required the transport study to be delayed to a later
date. The transport study was performed from
May 30 to June 13, using the EMSL-LV instrument
for all comparisons, as described below.
The spiked samples used for the transport
study were made in the same manner as the SPEW
samples, using the PEW that had been shipped to
EMSL-LV during the demonstration and stock-
solution ampoules originally intended for the
Wobum transport study. Two concentration
ranges, medium and high, were tested. Four 40-mL
VOA vials of each of the two concentration ranges
were prepared daily for 5 days, using fresh
ampoules each day. Two vials from each concen-
tration range were shipped and a corresponding set
was not shipped. The transported vials were pre-
served by acidifying to pH<2; the nontransported
vials were not The transported vials were shipped
in coolers at approximately 4 °C in the same man-
ner as the demonstration samples had been, using
the same overnight carrier service (Federal
Express). Samples were sent from Las Vegas to
the central Federal Express shipping hub, and were
returned the following morning to Las Vegas.
Nontransported samples were analyzed within 6
hours of preparation; transported samples were
analyzed within 30 hours of preparation. For the
first 3 days of the study the samples were prepared
and analyzed by one chemist, and for the last 2
days by a different chemist
Quality Assurance for the AVOAS
Demonstration
The purpose of the QA program for the
AVOAS demonstration was to ensure that the qual-
ity of data produced would be sufficient to allow
formulation of sound conclusions about the perfor-
mance of the AVOAS relative to the comparison
method.
According to the description of project cate-
gories specified in the EMSL-LV Quality Assur-
ance Program Plan (U.S. EPA, 1987), the AVOAS
demonstration is considered a Category n project.
Category n projects apply to measurement activi-
ties whose results are used by a client organization,
but not directly in regulatory, enforcement, legal,
or policy matters. The QAPjP addressed the key
elements required for Category n projects, and was
prepared in accordance with the guidance in Prepa-
ration Aids for the Development of Category n
Project Plans (U.S. EPA, 1991). The QAPjP
clearly identified and delegated responsibilities
related to all aspects of QA for this demonstration,
defined data quality objectives (DQOs), and
described the measures required to achieve the
DQOs.
Data Quality Objectives
The EPA recommends that DQOs include, at
a minimum, five indicators of data quality (Stanley
and Vemer 1983): representativeness, complete-
ness, comparability, accuracy, and precision. Table
2-4 summarizes the DQOs for the AVOAS demon-
stration.
DQOs were set to ensure that the study was
well enough designed and carried out for the com-
parisons to be as tree from confounding and extra-
neous sources of variability as possible. In
addition, because a fair assessment of the AVOAS
required that the performance of Method 502.2 be
known, it was important that DQOs be specified
for that method. DQOs were not set for the
AVOAS because the performance of that system
was unknown and its assessment was an objective
of the demonstration.
Representativeness Representativeness is
defined as "the degree to which the data accurately
and precisely represent a characteristic or a param-
eter, variation of a property, a process characteris-
tic, or an operation condition" (Stanley and Vemer,
1985). Representativeness was a particular issue in
this demonstration because the AVOAS is designed
to collect samples directly from a water treatment
stream with no manual intervention. In normal
operations, the samples are never exposed to air.
For this demonstration, analysis of spiked samples
(i.e., the SPEW, QCCS, and CCCS samples) by the
AVOAS required that the operator disconnect the
15
-------
sample line and introduce the samples in the off-
line mode. An estimate of the degree of represen-
tativeness of spiked samples was made by compar-
ing the results of TT samples analyzed on-line and
off-line by the AVOAS and by EMSL-LV. Repre-
sentativeness was optimized by using consistent
sample collection and preparation techniques and
by taking measures to ensure that sample integrity
was maintained to the highest degree possible.
Completeness The completeness of a data
set can be reduced by contamination, loss of sam-
ples due to vial breakage, and problems with cali-
bration, among other things. Completeness can be
monitored through use of appropriate QC samples,
i.e., instrument and travel blanks, CCCSs, and
QCCSs. The AVOAS demonstration plan was
designed to ensure maximum use of the resulting
data. Because each analysis provided more than
one type of data, for both QC and statistical analy-
sis purposes, the completeness objective for this
demonstration was 100%.
Comparability Comparability is defined as
"the confidence with which one data set can be
compared to another" (Stanley and Verner, 1985).
Analytical results from SPEW, TT, and QC sam-
ples were used to evaluate the comparability of the
two methods.
Accuracy Accuracy refers to the degree of
agreement of a measured value with the true, or
reference value for each analyte (Taylor, 1987).
Accuracy was assessed using data from daily anal-
yses of SPEW and QCCS samples and, for EMSL-
LV analyses, surrogate compound recoveries.
Accuracy was computed as the percent recovery
(%R) of measured concentrations relative to spiked
(target) concentrations for each analyte:
where:
, = measured concentration of analyte (p.g/L)
Ct = target concentration of analyte (jig/L)
TABLE 2-4. DATA QUALITY OBJECTIVES FOR THE AVOAS DEMONSTRATION
DQO Element
Demonstration Purpose
Computation
DQO
Representativeness
Completeness
Comparability
Assesses how well off-line AVOAS measurements Difference in mean %R for on- None set.
represented on-line AVOAS measurements to determine line and off-line treatment train
whether on-line AVOAS and EMSL-LV measurements could samples.
be compared. Analysis of variance.
Assesses the amount of useable data collected. %C
Determines how well AVOAS and EMSL-LV data compare.
100%
None set.
SPEW samples:
off-line AVOAS/EMSL-LV.
TT samples:
On-line AVOAS/ofMine AVOAS.
On-line AVOAS/EMSL-LV.
Off-line AVOAS/EMSL-LV.
%R
Difference in mean %R.
Difference in mean %R.
Accuracy
Precision
Compares agreement of AVOAS measurements with target %R
concentrations and with EMSL-LV measurements.
Compares variability among replicate measurements for the %RSD
AVOAS and EMSL-LV.
%R within 100 ±30%
for Method 502.2*
%RSD 530% for
Method 502.2*
%fl: Percent recovery, computed as Xfl = (Cm/Ct) 100, when Cm = measured analyte concentration (fig/L),
C, = target analyte concentration (ng/L).
Difference in mean %R: Difference in mean percent recovery, computed as mean %fl tor data set 1 minus mean %R for data set 2.
XRSD: Percent relative standard deviation, computed as %RSD = (standard deviation/mean) 100.
%C: Percent completeness, computed as %C = 100 V/n, where
V = number of valid measurements, n = total number of measurements.
' OOOs were not set for the AVOAS because the performance of that system was unknown and its assessment was an objective of the
demonstration.
16
-------
The accuracy DQO for the EMSL-LV instru-
ment, based on Method 502.2 performance data
and on performance data presented in a document
evaluating various water analysis methods (EPA,
1988), was 100 ±30%R for measured concentra-
tions relative to target concentrations of spiked
compounds.
Precision Precision is defined as the
degree of mutual agreement among individual
measurements (Taylor, 1987). Precision values
were computed for each compound and each sam-
ple type over the 6 days of the demonstration for
the AVOAS on-line and off-line and the EMSL-LV
measurements. Precision for this demonstration
was expressed as percent relative standard devia-
tion (%RSD), calculated as:
%RSD =
x 100
where:
a = standard deviation
\i = mean value of results over the 6 days of
the demonstration
The precision DQO for Method 502.2 analy-
ses was <30 %RSD.
Instrument Calibration
The AVOAS and EMSL-LV instruments were
calibrated within 2 days before the start of the
demonstration. A 5-point calibration curve was
used for the AVOAS, and a 4-point calibration
curve was used for the EMSL-LV instrument To
monitor instrument response during the demonstra-
tion, single-point calibration checks were per-
formed daily using the CCCSs. The calibration
standards for both instruments came from the same
supplier and lot so as to eliminate potential vari-
ability due to differences in concentration that can
occur in stock solutions from different sources.
The performance, expressed as percent differ-
ence (%D) between the initial and continuing cali-
bration responses for each analyte, was calculated
as follows:
%D = (C1-C2)xlOO/C1
where:
GI = response in the initial calibration
C2 = response in each continuing
calibration
A 20% difference between initial and con-
tinuing calibration was set as the acceptance crite-
rion for the EMSL-LV instrument.
Quality Control Samples
Quality Control Check Standard To moni-
tor instrument sensitivity and performance, the
QAPjP required daily analysis of a quality control
check standard (OjCCS) by each instrument.
QCCSs were made from commercially prepared
stock standards (Restek) having certified concen-
trations of five target analytes. The QCCS samples
for the AVOAS were made daily at the field site by
the LESC supervising chemist using PEW; a new
ampoule of stock standards was used each day.
The QCCS for the EMSL-LV instrument was made
by the EMSL-LV analyst using reagent-grade
water, the same stock solution ampoule was used
for the duration of the demonstration.
Continuing Calibration Check Standards
The QAPjP required daily analysis of continuing
calibration check standards (CCCSs), to provide an
ongoing indication of instrument performance.
CCCSs were one of the standards that had been
used to calibrate the instruments prior to the dem-
onstration. For the EMSL-LV instrument, the
CCCS concentration was 20 jig/L; for the AVOAS,
it was 400 ng/L. The CCCS for the AVOAS was .
made daily by the AVOAS operator from a fresh
stock standard ampoule; the EMSL-LV daily check
was performed using a standard prepared at the
beginning of the demonstration.
Instrument Blank Samples Instrument
blanks were samples of VOC-free water (PEW,
reagent-grade water, or VOC-free water from sam-
ple port S-6) analyzed to verify that the analytical
systems were not contaminated. For the systems to
be considered free of contamination, target analyte
concentrations were required to be below the low-
concentration SPEW sample or the MDL, which-
ever was less.
Travel Blank Samples Travel blank sam-
ples were used to determine whether routine sam-
ples may have been contaminated during shipping
or handling. Travel blanks were unspiked PEW
sent with each batch of TT and SPEW samples to
EMSL-LV. Travel blank samples were also used in
the transport study.
Demonstration Methods
EPA Method 502.2 Requirements and
Modifications
The procedures for instrument setup, initial
calibration, continuing calibration checks, addi-
tional QA/QC measures, and associated corrective
17
-------
actions are specified in EPA Method 502.2 and are
summarized in Table 2-5. Some modifications to
the method were used for this demonstration:
1. Method 502.2 requires the use of a photoioniza-
tion detector (FED), and electrolytic conductiv-
ity detector (ELCD). in series. The AVOAS
instrument was used with only the ELCD
because the target analytes in this study were
halogenated hydrocarbons, which are best mea-
sured using this detector. Both PID and ELCD
were used with the EMSL-LV instrument; how-
ever, the PID served only as an operator perfor-
mance guide, and the PID data were not
included in the demonstration database.
2. Compounds with chromatographic retention
times greater than that of PCE were not detected
in any of the samples. Therefore, the analytical
run times were shortened to increase sample
throughput (i.e., the number of samples that can
be analyzed in a given amount of time).
3. Method 502.2 requires that reagent water forti-
fied with target analytes at low concentrations
(just above the method PQLs). be analyzed as a
laboratory-fortified blank once each day or once
every 20 samples. This QC procedure was not
included in the demonstration, since five of the
eight daily analyses were performed on spiked
water samples.
TABLE 2-5. METHOD 502.2 QUALITY CONTROL REQUIREMENTS
QC Element
Speciflcationi
Acceptance Criterli
Corrective Action
1. Initial calibration
2. Continuing calibration
verification
3. Initial demonstration of
precision and
accuracy
Note: These analyses
were performed as
part of the PE study.
4. Quality Control Check
Standards
(commercially
prepared)
5. Instrument/reagent
blank
Purged effluent water
blank
7. Surrogate
All target compounds and
surrogate(s) at three-five
concentration levels
One or more standards analyzed
on each working day
Four to seven replicates of a low
level (0.5 5 ng/L) water sample
Analyze once each day at the
end of sample analysis
Compounds at concentrations
known to analysts
Daily, prior to standard or
sample analysis
Following samples containing
analytes > the high standard
< 10% RSD over concentration range Plot calibration curves for
required to use mean RF for quantitation analytes with RSOs >10%
RF or response (height or area) for each
analyte 120% of RF or response for that
analyte in the initial calibration standard
The mean accuracy (% recovery) should
be 80-120 %, and the
%RSD should be < 20 %
The MOL must be sufficient to detect
analytes at the regulatory levels
Recommended recoveries are
70-130%
Monitor any loss of instrument sensitivity
over the day, based on low-level analyte
recoveries
No analytes present >MDL or low level
standard, which ever is less
One per sample shipment batch No analytes present >MDL or low level
Trip blank for laboratory standard, which ever is less
samples
In each blank, TT sample,
spiked sample, and standard
2-bromo-1-chloropropane
Recommended recovery is 80 -120 %
Repeat the test using a fresh
standard
If test fails, recalibrate or prepare
a new curve
Perform new initial calibration or
perform maintenance, and rerun
the analyses
None specified, limits are advisory
»Repeat until blank meets the
acceptance criteria
Decontaminate instrument
None specified, flag sample
results with 'B'
Check calculation, standard
solution
No other specified, flag
associated sample data as
estimated,' J1
%RSD: % Relative standard deviation
MDL: Method Detection Limit
RF: Response factor
TT: Treatment Train
18
-------
4. A surrogate compound was not included in the
QC requirements for the AVOAS, because a
sample containing a surrogate could not be
introduced into the AVOAS in the on-line mode.
Sample Analysis
Table 2-6 summarizes the components and
operating conditions used for the AVOAS and
EMSL-LV analytical systems during the demon-
stration.
AVOAS
A Scientific Research Instruments Model
8610 GC equipped with a Tremetrics Model 1000
ELCD was used with the AVOAS for the field
demonstration. The GC signal integrator was a
Spectra-Physics, Model SP4400. An IBM-compat-
ible 286 microcomputer was used to control the
operation of the analytical system and to collect
and store the analytical data. The AVOAS was
operated at the field site by its inventor. Off-line
TT samples were generally analyzed immediately
after collection. SPEW samples were analyzed
within several hours of preparation.
EMSL-LV Method 502.2 Analyses
EMSL-LV analyses were performed using a
Hewlett Packard (HP) Model 5890 Series 2 GC
with an OI Model 4420 ELCD. The purge-and-
trap unit was an 01 Model 4460 with an MPM-16
autosampler. The integrator was an HP 3396. All
analyses for the demonstration were performed by
the same analyst, who was experienced in opera-
tion of the instrument Samples were received the
morning following shipment from Woburn and
were usually analyzed mat day. Exceptions were
samples from the first day of the demonstration
were analyzed by EMSL-LV 2 days after they were
shipped from Wobum, and those from the last day
were analyzed 4 days after they were shipped.
Data Management
Data for both the AVOAS and EMSL-LV
were handwritten onto forms. The AVOAS data
were checked for compound identification and
integration errors, completeness, and consistency
at the field site by the AVOAS operator. EMSL-LV
results were checked initially by the LESC analyst
and were reviewed by the project QA manager.
Hard copies of the chromatograms and correspond-
ing data (including chromatographic peak retention
times, peak areas, calculated concentrations, injec-
tion volumes, injection times, and sample identifi-
ers) for all analyses, and instrument logbook pages
were submitted for review. The LESC data base
manager reviewed the field and laboratory results,
identified any data that appeared unusual, and rec-
onciled the results prior to data base entry. All
database entries were checked by a second per-
son. Final hard copy and electronic results were
accompanied by case narratives that described any
problems or data interpretation difficulties, and
associated corrective actions.
Data Analysis
In addition to the computations described in
the QA/QC section, comparisons of differences in
mean %Rs for sample pairs were computed. The
advantage of using paired samples (with the pairs
being prepared and sampled under as nearly identi-
cal conditions as possible) is that the effect of
uncertainty in the true concentrations of samples is
reduced; also, accuracy comparisons thereby
become insensitive to any possible differences in
precision between the two methods being com-
pared. The analyses were done mostly in terms of
%Rs rather than actual measurements simply for
ease of interpretation and comparison across differ-
ent concentration levels and compounds. This
approach was taken for the SPEW and transport
study data, because of uncertainties in actual spik-
ing concentrations. For TT samples, this approach
was necessary because the true concentration of
those samples was unknown and possibly varied
with time.
For the purpose of obtaining approximate tar-
get concentrations to compute %Rs for TT sam-
ples, a weighted least-squares regression line was
fit through the origin for SPEW samples for the
AVOAS off-line and, separately, for EMSL-LV
analyses. Mean measured concentrations were
adjusted by the respective line to provide estimates
of target concentrations for each port. These esti-
mates were averaged when both AVOAS and
EMSL-LV estimates were available. Measure-
ments were converted to approximate %Rs so that
results could be expressed on the same scale across
different true concentration ranges and com-
pounds. This conversion does not affect the preci-
sion results or the hypothesis tests of whether the
mean recoveries are equal. The target concentra-
tion value is rough, and is used only for converting
differences in mean measurements between mea-
surement modes so as to approximate differences
in mean %Rs.
19
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TABLE 2-6. INSTRUMENT COMPONENTS AND OPERATING
Instrument
Gas Chromatograph
Column
Carrier gas, flow rate
Oven temperature program
Purge and Trap Sampler
Purge gas, flow rate
Purge time
Desorb time
Bake time
Trapping temperature
Oesorb preheat
Oesorb temperature
Bake temperature
Valve/transfer line temp.
Hall Detector
Reactor temperature
Reactor base temperature
Makeup gas, flow rate
Reaction gas, flow rate
n-Propanol flow
Photoionization Detector
Intensity
mV Signal
. Base temperature
Integrator
Computer
Software
AVOAS System
SRI 8610
DB-624, 30-m (J&W)
He, 6 cc/min
Initial 35°C
0.5 min 408C
2.5 min 45°C
10.0 min 50°C
12.5 min 65°C
A'RT
He, 12 cc/min
10 min
2 min
8 min
30°C
180°C
215°C
215°C
130°C
Tremetrics
885°C
250'C
He, 25 cc/min
H2, 25 cc/min
60 jiL/min
Not used
-
Spectra-Physics 4400
IBM-Compatible 286
A*RT
CONDITIONS
EMSL-LV
HP 5890 Series 2
RTX502.2, 105-m (Restek)
He, 10 cc/min
45°C, 60C/minto143°C
(no hold time)
01 4460 with MPM-16 auto-sampler
He, 40 cc/min
11 min
2 min
12 min
28"C
165°C
180"C
180°C
80°C
01 Model 4420
8008C
240°C
He, 30 cc/min
H2, 85 cc/min
50 u,l/min
01 Model 4330
6
11.9
2358C
HP 3396
IBM 286 PC
HP File server
20
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TABLE 2-7. CHRONOLOGY OF AVOAS DEMONSTRATION ACTIVITIES
Predemonstration Activities
Project planning, experimental design
Preparation of Demonstration and QA Plans
Performance Evaluation Study
Date
March, 1991
April, 1991
April 12-15,1991
Preparation of ampoules of stock solutions for spiked purged effluent water samples at EMSL-LV May 8,1991
Demonstration Activities
Installation of AVOAS May 14*17,1991
Preparation of purged effluent water at field site May 16,1991
Demonstration:AVOAS analyses May 18-24,1991
EMSL-LV Method 502.2 analyses May 20-May 28,1991
Transport Study May 30-June 13,' 1991
The %Rs for each of the method pairs were
computed for each day, and the mean values for
each method over days were computed. The differ-
ences were assessed using paired-sample t-tests
with a hypothesis of no difference in mean %Rs.
Confidence intervals were also computed. For
similar performance between two systems or treat-
ments, one would expect a difference in mean %R
of zero, with some allowance for random variabil-
ity. The major advantage of paired comparison t-
tests is their simplicity and ease of interpretation.
In statistical terms, the paired-sample t-test
amounts to blocking all other effects, and focusing
only on the one effect of interest Robustness is
attained at the cost of degrees of freedom.
Paired-sample t-tests were used to assess all
pairs of sample data. An Analysis of Variance
(ANOVA) was used to evaluate TT sample data
with respect to time of sample collection, day-to-
day variability, mode of analysis (i.e., AVOAS on-
line, AVOAS off-line, and Method 502.2), and
sample port An ANOVA models other effects
which are either expected to be present or are pos-
sibly present and cannot be ruled out In an
ANOVA analysis, not all other effects which might
be present are accommodated. On the other hand,
if the model fitted for the other effects reasonably
accommodates those that are in fact present one
obtains more degrees of freedom for error esti-
mates, and hence better sensitivity (power). In
addition, the ANOVA allows one to assess those
other effects.
AVOAS Demonstration Activities
A chronology of the activities and schedules
for the AVOAS demonstration are included in
Tables 2-7 and 2-8.
Activities prior to the demonstration included
site reconnaissance, preparation of the Demonstra-
tion and QA Plans, the PE study, and preparation
of spiking ampoules. Demonstration participants
arrived at the Woburn field site on May 13. While
the AVOAS was being installed, tested, and cali-
brated by A+RT, Inc., the EMSL-LV demonstration
participants selected sample ports to be used for
the demonstration, set up an area for preparing and
shipping samples, and prepared and checked the
PEW.
Daily activities at the field site during the
demonstration included preparing SPEW, CCCS,
and QCCS samples; collecting TT samples; prepar-
ing and shipping samples to EMSL-LV; entering
and reviewing data; and analyzing the required
AVOAS samples. Daily activities at the EMSL-LV
laboratory included preparing QCCS and CCCS
samples, receiving and logging in samples, per-
forming the surrogate spikes, analyzing samples,
and entering and reviewing data on the data
spreadsheets.
Activities performed after the field portion of
the demonstration included the transport study,
data validation and verification, and data analysis
and interpretation.
21
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TABLE 2-8. SCHEDULE OF SAMPLE ANALYSES FOR THE AVOAS AND EMSL-LV
AVOAS
5/18/91
B(S6)
TTF (S3)
TTF (S3)
CCCS
L
H
S
M
QCCS
TIN (S4)
TTF (S4)
5/20/91
B(S6)
TTF (S4)
TTF(S4)
CCCS
S
H
M
L
QCCS
TTN (S3)
TTF (S3)
15/21/91
TTN (S4)
TTF (S4)
CCCS
L
M
M
S
QCCS
TTN (S3)
TTF(S3)
B (PEW)
5/22/91
TTN (S4)
TTF (S4)
CCCS
S
L
M
H
QCCS
TTN (S3)
TTF (S3)
B (PEW)
5/23/91
TTN (S3)
TTF (S3)
CCCS
H
M
S
L
QCCS
TTN (S4)
TTF (S4)
B (PEW)
5/24/91
TTN (S3)
TTF (S3)
CCCS
TTN (S4)
TTF(S4)
L
M
H
S
QQCS
EMSL-LV
5/20/91
(Samples
5/18/91)
B (Water)
CCCS
B (PEW)
L
M
H
S
TTA (3)
TTP (3)
QCCS
fl (S6):
B (PEW):
B (Water):
CCC:
QCCS:
Sur:
TTA:
TTF:
TTN:
TTP:
5/21/91
from (Samples from
5/20/91)
B (Water)
Recal'
B (PEW)
L
M
H
S
TTA (2)
TTP (2)
B (PEW)
QCCS
5/22/91
(Samples from
5/21/91)
B (Water)
CCCS
B (PEW)
H
L
M
S
TTA (2)
TTP (2)
QCCS
Recalibrated with 2, 20, 50, WO ppb standards.
VOC-lree sample from port 56 (blank)
VOC-lree purged effluent water (blank)
Reagent-grade water (blank)
Continuing calibration check standard.
Quality control check standard.
Reagent-grade water spiked with 2-bromo-l-
chloropropane surrogate
Treatment train sample, a.m.
Treatment train oil-line sample (AVOAS).
Treatment train on-line sample (AVOAS).
Treatment train sample, p.m.
5/23/91
(Samples
5/22/91)
B (Water)
CCCS
Sur
B (PEW)
L
M
H
S
TTA (2)
TTP (2)
QCCS
(S3):
(S4):
(2) or (3):
H:
L:
M:
S:
5/24/91
from (Samples from
5/23/91)
Sur
CCCS
B (PEW)
L
M(2)
H
S
TTA (2)
TTP (2)
QCCS
5/28/91
(Samples from
5/24/91)
Sur
CCCS
B (PEW)
L.
M
M
S
TTA (2)
TTP (2)
QCCS
QCCS
Port S-3 sample.
Port S-4 sample.
Number of sample replicates, analyzed.
High spiked purged effluent water samples.
Low spiked purged effluent water samples.
Medium spiked purged effluent water samples.
Superhigh spiked purged effluent water samples.
22
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Section 3
AVOAS Demonstration Results and Discussion
Operational Results
The AVOAS demonstration went smoothly.
Both the AVOAS and the EMSL-LV instruments
were operational for the entire demonstration, and
all of the samples specified in the Demonstration
Plan were collected.
Initial installation and preliminary testing of
the AVOAS took 2-1/2 days. The problems that
occurred during installation were typical for an ini-
tial field site setup, and included delays and dam-
ages in shipping and the need to modify the site
facilities (e.g., installing an air conditioner and
vent).
During the ground-water treatment system
pilot study of May 18 through May 30, 1991, the
AVOAS processed 65 samples for the SITE dem-
onstration (not including QC samples), 192 auto-
mated treatment system samples, 52 samples
analyzed for another treatment project, and 41 cali-
bration and blank samples. The AVOAS ran an
average of 22.3 hours per day and processed an
average of 24.4 samples per day, at an average run
time of 55 min per sample. Further details of the
AVOAS field performance, as reported by the
developer, are included as Appendix A.
Deviations from the Demonstration Plan
were minor, and their impact on the results is
judged to be negligible. Modifications were made
because of the large number of samples scheduled
to be processed by the AVOAS during the same
period, beyond those required for this demonstra-
tion. Deviations included:
1. Rescheduling the transport study until after the
demonstration, with analysis of the transport
study samples by EMSL-LV rather than by the
field team.
2. Adjusting the planned sequence for sample anal-
ysis. Originally, the plan was to analyze the
CCCS as the first sample of the day, and the
QCCS as the last The heavy analysis schedule
for the SITE demonstration and for other
projects required modifying the sampling
sequence so that the TT samples from port S-3
or S-4, which were analyzed last for routine
monitoring purposes, would be the first samples
for the AVOAS demonstration, analyzed as on-
line TT samples.
3. Using the routine TT sample from port S-6
instead of a PEW sample as a system blank.
This sample was used only if the S-6 sample
was found to have target analyte concentrations
<1.0 u.g/L.
4. The AVOAS requires flushing of sample loops
between analyses, and has a built-in mechanism
for producing VOC-free water from TWP water
for that purpose. However, at the demonstration
site, the tap water contained a substance (possi-
bly residual flux from new copper tubing) that
caused a foaming problem. Bottled, purified
water was used instead for flushing.
Quantitative Results for Comparison
Studies
Comparison of the AVOAS and Method
502.2 Results for Treatment Train Samples
Tables 3-l(a-c) are compilations of results for
TT samples analyzed by EMSL-LV and by the
AVOAS in the on-line and off-line modes. Tables
3-2(a,b) summarize mean, standard deviation, and
%RSD for EMSL-LV and AVOAS data by port and
time.
Table 3-3 summarizes differences in mean
%Rs for analytical mode comparisons for each of
the three paired-analysis combinations (AVOAS
on-line/AVOAS off-line; AVOAS off-line/EMSL-
LV; AVOAS on-line/EMSL-LV) for samples from
ports S-3 and S-4 and for bom ports combined,
over the demonstration period. Paired-sample t-
tests of the hypothesis of no significant difference
in mean %Rs were performed, and significance
results are shown in Table 3-3.
23
-------
TABLE 3-1 (a). TREATMENT TRAIN SAMPLE RESULTS
Compound
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
trichloroethene
tetrachloroethene
MOL
(ng/L)
6.0
17.0
8.0
6.0
23.0
22.0
30.0
1
a.m.
S-3
7.1
U
U
12.8
26.6
53.1
2042
p.m.
S-4
6.5
U
U
U
37.9
49.3
2177
Detected
2
a.m.
S-4
U
U
U
11.6
22.8'
50.3
1882
FOR EMSL-LV
ANALYSES
Concentration, |ig/L, for Demonstration
p.m.
S-3
U
U
U
10.1
22.6'
49.3
2006
3
a.m. p.m.
S-4 S-3
U U
U U
U U
8.3 11.3
19.8' 25.3
41.4 50.2
1915 1824
4
a.m. p.m.
S-4 S-3
U 6.2
U U
U U
7.6 13.5
19.4* 24.3
42.9 54.9
1837 2188
Days 1 through 6
5
a.m.
S-3
6.4
U
U
13.5
27.8
56.1
2204
p.m.
S-4
U
U
U
8.2
17.3'
39.4
2157
a.m.
S-3
7.9
U
U
17.4
38.5
73.1
2133
6
p.m.
S-4
5.9'
U
U
10.1
27.7
45.3
2207
TABLE 3-1 (b). TREATMENT TRAIN
Compound
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
trichloroethene
tetrachloroethene
UDL
(H9/L)
2.5
0.5
1.0
1.0
3.5
1.5
0.5
1
a.m.
S-3
9.2
U
4.1
16.5
30.3
56.3
1924
SAMPLE RESULTS
p.m.
S-4
11.7
2.4
4.8
21.0
51.7
82.6
2713
Detected
2
a.m.
S-4
9.8
U
2.6
12.8
20.1
48.1
1986
FOR THE AVOAS ON-LINE ANALYSES
Concentration, ng/L, for
p.m.
S-3
6.8
1.4
4.1
17.6
33.8
64.3
2124
3
a.m. p.m.
S-4 S-3
4.0 7.4
U 2.2
2.7 4.4
12.5 19.7
23.5 36.2
48.6 74.4
2058 2368
Demonstration
4
a.m. p.m.
S-4 S-3
7.1 7.1
U 1.6
3.3 3.7
13.4 20.0
25.0 33.2
50.1 72.6
2249 2370
Days 1 through 6
a.m.
S-3
5.8
U
3.4
19.3
36.8
77.3
2366
5
p.m.
S-4
4.9
1.7
3.5
15.5
30.5
63.0
2385
a.m.
S-3
3.7
U
3.7
23.8
45.8
95.1
3030
6
p.m.
S-4
5.2
1.5
3.4
17.7
36.6
72.3
2758
TABLE 3-1 (C). TREATMENT TRAIN
SAMPLE RESULTS
FOR THE AVOAS OFF-LINE ANALYSES
Detected Concentration, ug/L, for
Compound
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
trichloroethene
tetrachloroethene
UDL
(H9/L)
2.5
0.5
1.0
1.0
3.5
1.5
0.5
1
a.m.
S-3
7.3
U
4.2
16.7
35.0
58.0
1944
p.m.
S-4
9.1
1.7
3.8
15.7
39.2
63.3
2406
2
a.m.
S-4
5.0
U
2.6
12.2
26.4
49.3
2123
p.m.
S-3
5.3
1.3
3.8
17.8
35.7
64.7
2195
3
a.m. p.m.
S-4 S-3
3.2 6.9
U 1.5
2.6 4.2
11.8 20.5
25.3 37.4
46.6 72.3
2039 2365
Demonstration
4
a.m. p.m.
S-4 S-3
5.3 6.4
U 0.9
3.0 3.5
12.9 18.5
25.8 36.4
50.9 71.0
2289 2391
Days 1 through 6
a.m.
S-3
3.1
U
3.2
17.6
39.8
73.6
2219
5
p.m.
S-4
5.3
1.7
3.2
14.7
32.3
64.2
2278
a.m.
S-3
3.3
U
3.7
23.1
45.5
93.2
2921
6
I-J'
6.1
1.1
3.8
16.3
36.3
70.1
2806
Vinyl chloride and 1,2-dichloroethane were not detected by either EMSL-LV or the AVOAS, so those compounds are not included in this table.
MDL: Method Detection Limit
U: Below instrument detection limits.
': Estimated value; measured concentration below calculated method detection limit.
24
-------
Table 3-4 summarizes the results of analysis
of variance (ANOVA) computations, performed to
determine the significance of effects on the data
attributable to port (S-3 or S-4); time of day (mom-
ing- or afternoon-collected samples); day-to-day
differences over the demonstration period; and
mode or analytical system differences (AVOAS
on-line, AVOAS off-line, and EMSL-LV). Mea-
sured concentrations were used for the ANOVA
computations. Results for each compound were
computed separately for the EMSL-LV dat«. the
AVOAS data, and for the AVOAS and EMSL-LV
data combined.
Mode Comparisons
AVOAS On-line and Off-line Mode Compari-
sons For all compounds and ports, the measured
concentrations were greater for on-line than for
off-line measurements (except for 1,1,1-TCA).
The difference in mean %R results indicated, how-
ever, that this difference was not significant or only
slightly significant for most pairs. The difference
in mean %R was greater for the two most volatile
compounds (1,1-DCE and trans-1,2-DCE) than for
the other compounds. It must be pointed out that
the concentrations for the higher volatility com-
pounds in the TT samples were very low (close to
instrument detection limits) for 1,1-DCE, trans-
1,2-DCE, and 1,1-DCA compared to the lower vol-
atility compounds, particularly TCE and PCE,
which had concentrations of around 65 (ag/L and
over 2300 jig/L, respectively. For TCE and PCE,
the differences in mean %R between on-line and
off-line sample analyses were very low (less than
TABLE 3-2(a). SUMMARY OF MEAN, STANDARD DEVIATION, AND %RSD FOR PORT MEASUREMENTS FOR
EMSL-LV, AVOAS ON-LINE, AND AVOAS OFF-LINE ANALYSES OF TREATMENT TRAIN SAMPLES ACROSS
THE SIX DAYS OF THE DEMONSTRATION
Compound
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
trichloroethene
tetrachloroethene
Compound
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
trichloroethene
tetrachloroethene
Hean
EHSL
LV
*
U
U
13.1
27.5
56.1
2066
Hcan
EHSL
LV
6.2
U
U
9.2C
24.2
44.8
2029
Concentration, iig/L
AVOAS
On-Llne
6.7
b
3.9
19.5
36.0
73.3
2364
AVOAS
Off-line
5.4
b
3.8
19.0
38.3
72.1
2339
Concentration, iig/L
AVOAS
On-Llne
7.1
b
3.4
15.5
31.2
60.5
2358
AVOAS
Off-lint
5.7
b
3.2
13.3
30.9
57.4
2324
Port 3
Standard Deviation
EHSL-
LV
2.5
5.7
8.7
142
AVOAS
On-Llne
1.8
b
0.4
2.5
5.3
13.1
373
Port 4
AVOAS
Off-lint
1.8
b
0.4
2.4
3.9
11.9
323
EHSL-
LV
-
19.1
20.6
15.5
6.9 .
Standard Deviation
EHSL-
LV
0.4
1.7
7.6
4.4
168
AVOAS
On-Llne
3.0
0.8
3.3
11.6
14.8
325
AVOAS
Off-line
1.9
0.5
1.9
6.0
9.7
270
EHSL-
LV
6.8
18.0
31.6
9.7
8.3
%RSD
AVOAS
On-Llne
27.4
b
9.3
12.9
14.8
17.9
15.8
%RSD
AVOAS
On-Llne
42.9
23.3
21.6
37.1
24.4
13.8
AVOAS
Off-line
33.8
b
10.4
12.4
10.2
16.4
14.0
AVOAS
Off-line
34.2
17.1
13.6
19.3
16.8
11.6
U: Below instrument detection limits.
1 Six of 12 values were 'U'; no computations.
* Trans-1,2-dichlomothene was detected in p.m. samples only.
" Based on n=5, because one value was 'U.'
25
-------
TABLE 3-2(b). SUMMARY OF MEAN, STANDARD DEVIATION, AND %RSD FOR SAMPLE TIME MEASURE-
MENTS FOR EMSL-LV, AVOAS ON-LINE, AND AVOAS OFF-LINE (A.M. AND P.M.) ANALYSES OF TREATMENT
TRAIN SAMPLES ACROSS THE SIX DAYS OF THE DEMONSTRATION
Compound
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroelhane
cis-1,2-dichloroethene
1,1,1-trichloroelhane
trichloroethene
tetrachloroethene
Compound
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
trichloroethene
tetrachloroethene
Mean
EMSL
LV
a
U
U
11.9
25.8
52.8
2002
Mean
EMSL
LV
6.2
U
U
10.6e
25.9
48.1
2093
Concentration, ug/L
On
6.6
U"
3.3
16.4
30.3
62.3
2269
OH
4.3
U"
3.2
15.7
33.0
61.9
2256
Concentration, ng/L
On
7.2
1.8
4.0
18.6
37.0
71.5
2453
Off
6.5
1.4
3.7
17.3
36.2
67.6
2407
A.M.-
Collected
Samples
Standard Deviation
EMSL-
LV
0.8
-
-
3.6
7.1
11.5
148
P.M.-
On
2.6
b
0.6
4.5
9.6
19.7
408
Collected
Off
1.7
b
0.6
4.4
8.5
18.1
348
Samples
EMSL-
LV
10.5
-
30.4
27.5
21.7
7.4
Standard Deviation
EMSL-
LV
0.3
1.9C
6.9
5.2
150
On
2.4
0.40
0.5
2.0
7.5
7.2
240
Off
1.4
0.33
0.3
2.1
2.3
4.0
211
EMSL-
LV
4.8
-
18.3C
26.5
10.9
7.2
%RSD
On
39.0
b
17.4
27.3
31.7
31.6
18.0
%RSD
On
34.0
22.5
13.8
10.9
20.4
10.0
9.8
Off
36.7
b
19.7
27.7
25.8
29.3
15.4
Off
21.7
23.3
9.1
12.2
6.3
5.9
8.8
U: Below instrument detection limits.
1 Six ol 12 values were 'U'; no computations.
b Trans-12-dichloroethene was detected in p.m. samples only.
c Based on n=5, because one value was 'U.'
5% overall). The ANOVA results support the find-
ing of no significant difference due to on-line or off-
line modes, except for the high volatility, low con-
centration analytes 1,1-DCE and trans- 1,2-DCE.
AVOAS and EMSL-LV Comparisons The
very high concentrations of PCE required sample
dilution to bring PCE concentrations to within the
linear range of the EMSL-LV detector. Sample
dilution reduced the quantity of the lower concen-
tration analytes (1,1-DCE, trans- 1,2-DCE, 1,1-
DCA, cis-1,2-DCE, and 1,2-DCA) to below the
MDLs of the EMSL-LV instrument. Furthermore,
the MDLs for the EMSL-LV instrument were some-
what higher than those for the AVOAS; i.e., the
AVOAS instrument had greater sensitivity than the
EMSL-LV instrument. For these reasons, the
AVOAS results indicate detectable concentrations
of analytes for a number of samples for which con-
centrations were below the MDLs of the EMSL-
LV detector.
For analytes detected by both instruments,
virtually all of the AVOAS concentrations for both
the on-line and off-line modes were higher than the
EMSL-LV values, and all differences in mean %R,
with the exception of 1,1-DCE and PCE for port S-
3, were statistically significant at the 10% level.
For the on-line AVOAS and EMSL-LV compari-
sons, the difference for TCE was approximately
21% for samples from both ports, and for PCE,
approximately 12% for samples from both ports.
The ANOVA results reinforce the finding of a sig-
nificant effect due to analytical system. Figure 3-1
26
-------
shows EMSL-LV and AVOAS on-line and off-line of all compounds measured for port S-3 samples,
TT sample results, averaged over port and time of except for 1,1-DCE, were greater than those for
day- port S-4 samples. The ANOVA results indicate that
Sample Port Differences For all AVOAS ** differences were statistically significant for 1,1-
on-line and off-line measurements, concentrations DG\, cis-l,2-DCE, 1,1,1-TCA, and TCE. It is
possible that these differences reflect actual differ-
TABLE 3-3. DIFFERENCE IN MEAN PERCENT RECOVERIES FOR TREATMENT TRAIN SAMPLES ANALYZED
BY THE AVOAS AND EMSL-LV.
On-line - Off-line AVOAS
Compound
1,1-dichloroethene*
trans- 1 ,2-dichloroethene*
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
trichloroettiene
tetrachloroethene
Ports
19S
37 NS
4M
2NS
6S
2NS
1 NS
Port 4
25 NS
26 NS
6NS
12 M
1NS
5NS
INS
Off-lint -
Port3
3NS
c
c
31 S
29 S
23 S
11 M
EVSL-LV
Port 4
27 S
c
c
45 S
22 S
21 S
12 S
On-lint -
Ports
16 NS
c
c
34 S
23 S
21 S
12 M
EMSL-LV
Port 4
52 S
c .
c
57 S
23 S
26 S
13S
Vinyl chloride and 1,2-dichloroethane were not detected by either EMSL-LV or the AVOAS, so those compounds are not included in this table.
1 For EMSL-LV, two of six samples for Port S-3 and four of six samples for Port S-4 had concentrations below Instrument detection limits.
6 All morning AVOAS measurements had concentrations below instrument detection limits.
e Compound not detected by EMSL-LV Instrument; no computation possible.
NS: Not significant (p> 0.10).
M: Moderately significant (0.05 0.10).
M: Moderately significant (0.05
-------
ences in water composition for samples from each
port. However, for the EMSL-LV measurements,
the significance of port among analytes was vari-
able. The data are confounded by higher concen-
trations detected by the AVOAS in some afternoon
collected/analyzed samples compared to morning
samples.
Time Differences No significant differ-
ences for time of sample collection were detected
for any compound measured by the EMSL-LV
instrument; however, for the AVOAS, time of col-
lection/analysis effects were significant or highly
significant for every compound. The results for the
AVOAS afternoon analyses were always greater
Treatment Train Sample Results for 1,1-Dichloroethene
20-1
-5
10-
5-
Treatment Train Sample Results (or 1,1-Dlchloroethane
I
10-1
8-
4-
2-
3 DAY *
. AVOAS ON4JNC
5 6
AVOAS OFf-UNE
3 DAY *
AVOAS ON4JNE
AVOAS OFF-LINE
Treatment Train Sample Results for cls-1,2-Dlchloroethene Treatment Train Sample Results for 1,1,1 -Trlchloroethane
30
25
20
15
10
5
0
SO-i
40-
30-
20-
10-
1 2
- AVOAS ON4JN8
3 DAY*
5 8
AVOAS OFF-LW8 -M- EMSL-LV
Treatment Train Sample Results for THchloroethene
100.
80.
60.
40
20
DAY
-m- AVOAS OfHJM -e- AVOAS OfF-UHE -M-EMSL-LV
Treatment Train Sample Results for Tetrachloroethene
3500.
3000
3
1 z*00
8
2000
1500
2 3 DAY 4 5
»- AVOAS ON4JNI -«- AVOA3 OFF-UNI -M- EMSL-LV
1 2
I- AVOAS ON4JNI
3 DAY *
5
AVOAS OFHJM -M- EMSL-LV
Rgure 3-1. Treatment Train Sample Results. (Over all ports and times.)
28
-------
than those for the morning analyses. For example,
none of the morning AVOAS measurements con-
tained detectable concentrations of trans-1,2-DCE,
whereas all afternoon samples did. This finding is
consistent with carryover from higher concentra-
tion samples analyzed between the morning and
afternoon analyses. The superhigh-concentration
SPEW samples were analyzed between the mom-
ing and afternoon TT analyses using the same loop
as that used for the TT samples. The TT samples
contained much lower concentrations of all ana-
lytes (except TCE and PCE) than the superhigh-
concentration SPEW samples.
Day-to-Day Differences For the EMSL-
LV data, no significant differences in results from
day to day were observed. For the AVOAS, day-
to-day differences were statistically significant for
all compounds but one (trans-1,2-DCE). Although
the differences are significant, the magnitude is not
great Most values for TCE and PCE were within
± 30% of the 6-day mean concentrations. Possible
explanations for this finding could include: 1)
actual changes in treatment train water concentra-
tions over the demonstration period; 2) factors
intrinsic to the AVOAS, such as variations in
instrument function over the demonstration period;
or 3) random variability. The fact that the EMSL-
LV measurements show no significant day-to-day
difference suggests that variation in treatment train
water over the 6-day period is not an explanation.
Precision for Treatment Train Samples
Percent RSD values for both the AVOAS and
EMSL-LV were less than 25%, except for 1,1-DCE
for the AVOAS, which was 35% for the on-line
mode and 33% for off-line. Precision results for
the AVOAS in the off-Ike mode tended to be
slightly better than those for the on-line mode,
except for 1,1,1-TCA.
For EMSL-LV, the %RSDs for TCE and PCE
were 18% and 7% for all data over the 6 days. For
the AVOAS the corresponding %RSDs for TCE
and PCE were 20% and 12% for the off-line mode
and 22% and 14% for the on-line mode.
For all compounds except PCE, the %RSD
values for port S-4 were the same or greater than
those of port S-3.
Comparison of the AVOAS and Method
502.2 Results for Spiked Purged Effluent
Water Samples
Tables 3-5(a-d) are compilations of the
SPEW sample results of the AVOAS and EMSL-
LV analyses for each of the nine compounds at
each of the four concentration ranges. Table 3-6
summarizes data for differences in mean %Rs. The
results of paired-sample t-tests of the hypothesis of
no significant difference in mean %Rs between the
AVOAS and EMSL-LV are included in that table.
Plots of mean %Rs for both methods are shown in
Figure 3-2.
Mean %Recoveries Averaged Ovw Compound*
AVOAS SPIKED PURGED EFFLUENT WATER SAMPLES
140
130
120
110
100
90
80
70
60
SO
LOW
DAY
-e-MOM
-8UPHWMH
Mean %necovsns9j Averaged Over Compounds
EMSU.V SPIKED PURGED EFFLUENT WATER SAMPLES
140
130
120
110
100
90
80
70
60
SO
1 2
LOW -«.
3 DAY*
S 8
-M-SUPMMH
MMH %Racov*riM Averaged Over Compounds
and Levels
SPWED PURGED EFFLUENT WATER SAMPLES
140
130
120
110
100
90
80
70
80
SO
3 DAY4
.AVOAS
Figure 3-2. Spiked Purged Effluent Water Results.
29
-------
In every case, the mean %R was greater for the spiked target values; i.e., the %Rs were less
the AVOAS than for the corresponding EMSL-LV than 100%, whereas the AVOAS results were usu-
analysis. All but three of the differences were sig- ally close to or above the spiked values. The over-
nificant (p<0.05). For most analytes, the EMSL- all %R averaged over all compounds, days, and
LV measured concentrations were near or below concentration levels for EMSL-LV was 74%; that
TABLE 3-5
-------
for the AVOAS was 104%. Possible explanations
for these findings include: 1) differences in per-
formance of the instruments, 2) variability in ana-
lyst technique, or 3) transport or holding time
effects. The data indicate that a combination of
these sources may have contributed to the observed
results.
The day-to-day patterns for the AVOAS and
EMSL-LV are similar, though hot identical. Some
exceptions can be noted. For example, the AVOAS
results for the medium-concentration SPEW sam-
ple for day 4 had markedly lower concentrations of
all analytes compared to the other days and to
those for the EMSL-LV instrument; for day 3, the
TABLE 3-5(b). MEDIUM-CONCENTRATION SPIKED PURGED EFFLUENT WATER SAMPLE RESULTS FOR
EMSL-LV AND AVOAS ANALYSES
EMSL-LV
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
AVOAS
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
Detected Concentration,
Target
Cone.
(Mfl)
37.4
91.1
97.5
45.6
23.7
91.1
39.2
53.8
88.7
1
38.9
67.0
76.0
39.4
20.5
74.0
33.1
40.5
75.0
2
29.5
55.0
66.0
38.2
19.2
67.0
33.6
40.6
66.0
3
26.2
53.0
62.0
36.0
17.9
62.0
32.2
38.2
63.0
4
28.0
48.9
57.0
32.9
16.2
58.0
28.9
34.6
55.0
Detected Concentration,
Target
Cone.
(ug/i)
37.4
91.1
97.5
45.6
23.7
91.1
39.2
53.8
88.7
1
60.2
75.0
98.1
55.8
25.5
110
45.5
56.5
88.6
2
56.6
72.0
99.6
53.6
25.1
108
42.4
57.2
89.8
3
51.8
67.8
90.9
52.2
23.2
104
40.0
51.1
82.3
4
34.7
43.2
60.5
34.4
15.1
62.9
28.0
34.1
52.2
ng/L, by Day
5
33.9
58.0
61.0
34.5
16.7
62.0
28.1
35.3
56.0
6
27.0
44.3
52.0
29.4
14.2
60.0
26.9
30.0
46.8
Mean
Cone.
(Mrl)
30.6
54.4
62.3
35.1
17.5
63.8
30.5
36.5
60.3
ng/L, by Day
5
54.5
71.1
71.1
53.3
23.5
97.4
43.6
51.9
80.2
6
58.0
70.1
97.2
55.0
24.0
112
42.6
55.6
91.3
Mean
Cone.
(ng/L)
52.6
66.5
86.2
50.7
22.7
98.9
40.4
51.1
80.7
Summary
Standard
Deviation
4.9
7.8
8.2
3.6
2.2
5.8
2.8
4.1
9.8
%RSD
16.0
14.4
13.2
10.4
12.9
9.1
9.3
11.2
16.3
Mean
%R
82
60
64
77
74
70
78
68
68
Summary
Standard
Deviation
9.2
11.7
16.4
8.1
3.8
18.4
6.3
8.7
14.6
%RSD
17.6
17.6
19.1
16.0
16.8
18.6
15.6
17.0
18.1
Mean
%R
141
73
88
111
96
109
103
95
91
Target Cone.: Concentration of spiking solution.
Mean Cone.: Mean concentration over 6 days.
The standard deviation listed is for the measured concentrations (not for the %Rs).
%flSO: Percent relative standard deviation.
Mean %R: Mean percent recovery.
31
-------
EMSL-LV analyses of the low-concentration
SPEW samples had markedly lower concentrations
for all components than on the other days.
Precision for the AVOAS and for the EMSL-
LV instruments for the combined values across all
concentrations and compounds was similar (12.8
and 13.0%). Results for all four concentration
ranges were <30 %RSD for both the AVOAS and
the EMSL-LV data, with the exception of 1,1,1-
TCA in the low-concentration samples. The higher
(31 to 32%) RSD for the 1,1,1-TCA replicates was
TABLE 3-5
-------
a consequence of an exceptionally high concentra-
tion of this compound in the sample analyzed at
both locations on the last day of the demonstration.
It is possible that 1,1,1-TCA or a coeluting con-
taminant (i.e., a compound with a chromatographic
retention time close to that of 1,1,1-TCA) was
introduced into the samples at the site during
SPEW sample preparation. The average precision
for the AVOAS across all concentrations and com-
pounds was 12.6 %RSD; that for EMSL-LV was
13.3%. This difference is so small as to be of no
practical significance.
TABLE 3-5(6). SUPERHIGH-CONCENTRATION SPIKED PURGED EFFLUENT WATER SAMPLE RESULTS FOR
EMSL-LV AND AVOAS ANALYSES
EMSL-LV
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
AVOAS
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
Detected Concentration,
Target
Cone.
(1*9/1.)
747
1946
911
467
1822
788
1067
1774
1
580
1330
720
345
1280
650
810
1460
2
510
1240
680
305
1270
580
730
1240
3
580
1170
620
286
1310
530
690
1390
4
450
-
970
540
261
1080
493
590
1020
Detected Concentration,
Target
Cone.
(M9/L)
747
1946
911
467
1822
788
1067
1774
1
1211
2024
1109
547
2368
899
1277
2227
2
1038
1954
969
489
1861
784
1220
2129
3
1131
1823
949
456
1946
788
1127
1929
4
930
1754
881
430
1667
687
1071
1958
jig/L, by Day
5
730
1340
700
306
1380
570
750
.1310
6
630
1210
720
329
1280
550
720
1200
Mean
Cone.
(H9/L)
580
-
1210
663
305
1267
562
715
1270
ug/L, by Day
5
1218
1897
945
463
1973
747
1121
1935
6
1415
2114
1111
535
2494
955
1324
2450
Hem
Cone.
(M/L)
1157
1928
994
487
2053
810
1190
2150
Summary
Standard
Deviation
96.7
-
135
70.9
29.9
99.9
53
73.1
155
%RSD
16.7
-
11.2
10.7
9.8
7.9
9.4
10.2
12.2
Mean
%R
78
-
62
73
65
70
71
67
72
Summary
Standard
Deviation
167
132
94.6
46.3
313
99.1
99.2
208
%RSD
14.4
6.8
9.5
9.5
15.2
12.2
8.3
9.9
Mean
%fl
1S5
-
99
109
' 104
112
103
112
119
Target Cone.: Concentration of spiking solution.
Mean Cone.: Mean concentration over 6 days.
The standard deviation listed is for the measured concentrations (not for the %Rs).
%RSD: Percent relative standard deviation.
Mean %R: Mean percent recovery.
33
-------
TABLE 3-6. DIFFERENCE IN MEAN PERCENT RECOVERIES FOR SPIKED PURGED EFFLUENT WATER
SAMPLES ANALYZED BY THE AVOAS (OFF-LINE) AND EMSL-LV
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroettiene
tetrachloroethene
Low Spike
58
6NS
20
31
25
41
23
23
16
Medium Spike
59
13
25
34
22
39
25
27
23
High Spike
40
13 M
18 M
25
20
22
17
23
21
Superhigh
Spike
77
b
37
36
39
43
31
45
47
Mem, All
59
11
25
32
26
36
24
29
27
" All values significantly different, except as noted (p < 0.05).
* /, 1-dichlonethene not in superhigh-concentration sample.
NS: Not significantly different (p > 0.10).
U: Moderately significant (O.OS
-------
Transport Study - Medium Spited Samples
TETRACHLOROETHENE
Transport Study - High Spited Samples
TETRACHLOROETHENE
1*0
140
120
100
SO
CO
40
160
140
120
100
80
80
40
1
DAY
TRANSPORTED
4 5
. NOT TRANSPORTED
3
OAV
> TRANSPORTED
4 5
MOT TRANSPORTED
Figure 3-3b. Transport Study Results for Medium- and High-concentration Spiked Samples for
Tetrachloroethene.
TABLE 3-7(a). TRANSPORT STUDY RESULTS FOR MEDIUM SPIKED SAMPLES*
Detected Concentration, |ig/L,
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
Target
Cone.
(M9/L)
37.4
91.1
97.5
45.6
23.7
91.1
39.2
53.8
88.7
Trim
36.5
36.6
61.0
61.0
68.0
68.0
39.2
38.4
19.4
18.8
66.0
65.0
33.5
33.3
40.9
39.7
65.0
57.0
1
Not
Trim'
35.5
53.0
60.0
33.8
16.2
60.0
31.7
34.1
54.0
2 3
Trim
47.9
38.3
74.0
61.0
81.0
68.0
46.4
38.5
22.2
18.8
80.0
64.0
36.8
32.8
46.9
38.5
76.0
63.0
Not
Trim
36.3
51.0
70.0
75.0
78.0
80.0
41.6
43.1
21.9
20.8
48.4
70.0
35.8
36.0
42.3
46.8
67.0
79.0
Trim
35.8
54.0
60.0
99.0
39.4
50.0
26.1
30.5
17.3
20.8
34.3
38.7
25.2
27.8
27.8
33.3
37.8
45.9
Not
Trim
55.0
44.2
82.0
66.0
97.0
70.0
47.3
38.6
24.9
18.9
56.0
65.0
37.6
31.6
50.0
39.7
86.0
63.0
by Simple
4
Trim
103
86.1
97.6
98.6
94.1
95.4
53.3
52.2
25.5
29.5
89.7
101
41.9
47.7
56.0
54.7
81.9
87.2
Not
Trim
84.1
92.5
93.5
102
91.9
105
51.6
56.2
26.1
26.3
95.8
89.6
44.9
42.5
59.4
56.1
87.4
84.7
5
Trim
80.6
81.7
92.3
94.1
98.2
91.6
59.4
51.8
28.6
24.8
103
87.7
46.1
23.8
62.5
51.9
80.3
80.9
Not
Tram
93
127
102
130
99.5
128
56.8
78.4
27.1
36.3
99.6
127
44.6
61.5
57.7
77.4
86.9
110
" Results for duplicate samples for each treatment.
6 Duplicate sample not analyzed.
Trans: sample transported.
Not trans: sample not transported.
35
-------
TABLE 3-7(b). SUMMARY OF TRANSPORT STUDY RESULTS FOR MEDIUM SPIKED SAMPLES
Mean Concentration
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
Tram
59.8
79.9
75.4
43.6
22.6
72.9
34.9
45.2
67.5
Not Tram
68.7
85.9
89.9
49.7
24.3
79.0
40.7
51.5
79.8
Standard
Deviation
Trans
25.3
17.9
20.2
10.8
4.3
23.8
8.3
11.1
16.7
Not Tram
31.7
23.4
20.5
13.3
5.8
25.6
9.3
13.0
16.6
%RSD
Tram
42.1
22.4
26.8
24.7
19.1
32.6
23.8
24.4
24.7
Not Tram
46.1
27.2
22.8
26.7
24.0
32.3
22.8
25.2
20.8
Mean %R
Tram
160.6
87.7
77.3
95.6
96.4
80.1
89.0
84.0
76.1
Not Tram
183.8
94.3
92.2
109.0
103.8
86.8
103.8
96.6
89.9
Difference
in
Mean %R
23.2
6.7
14.9
13.4
7.2
6.7
14.8
11.7
13.9
Mean Concentration: Mean concentration tor duplicate samples lor live sample pairs.
%RSD: Percent relative standard deviation.
Mean %R: Mean percent recovery for duplicate samples (or live sample pairs.
Difference in mean %R: Difference in mean percent recovery between samples not transported and those transported.
Several instances for which transport effects
may have influenced the results can be observed.
The estimated loss in TCE concentration for the
medium-range transported sample was approxi-
mately 12%. However, the 90% confidence inter-
val expands the potential loss to approximately
28%, which is consistent with the results for the
AVOAS and EMSL-LV differences in mean %R
for SPEW samples.
Most of the %Rs for both transported and
nontransported samples, at both concentration
ranges, were less than 100%. It is impossible to
attribute with certainty a cause for these results;
however, explanations could include: 1) analyte
concentrations in the standards were less than the
certified amounts, and 2) chemist spiking or ana-
lytical technique. For the SPEW samples, EMSL-
LV %Rs also tended to be <100%. However, the
%Rs of the SPEW samples analyzed by the
AVOAS were close to 100%. The transport study
samples were made using the same spiking solu-
tions as those for the SPEW samples. In contrast,
the QCCS samples, which were prepared at the
respective locations, had %Rs close to 100% for
both the AVOAS and EMSL-LV. The stock solu-
tion used to make the QCCSs was not the same as
that used for the SPEW samples.
The results suggest that inter-analyst variabil-
ity was significant; that is, the difference in recov-
eries obtained by the two chemists was larger in
magnitude than any transport effect This inter-
analyst variability occurred despite the fact that
each analyst had recalibrated the instrument before
their respective days on the study. The analyst
variability seems to differ for the medium- and
high-concentration spikes. One explanation may
be the difference in dilution techniques used by the
analysts for the high-concentration samples. How-
ever, wide confidence intervals for each of the
spiking concentrations preclude definitive conclu-
sions. The analyst-to-analyst difference is similar
in magnitude to the AVOAS - EMSL-LV differ-
ences found in the TT and SPEW sample compari-
sons, leading one to speculate whether the real
differences between the AVOAS and EMSL-LV
mean %Rs are due to transport phenomena, differ-
ences between instruments, differences between
analysts, or a combination of these or other factors.
Linearity Study Results
Data for off-line analyses of the SPEW sam-
ples were used to check the linearity of response of
the AVOAS. The results suggest little evidence for
nonlinearity for most of the target analytes at most
36
-------
TABLE 3-8(a). TRANSPORT STUDY RESULTS FOR
HIGH SPIKED SAMPLES
Detected Concentration, ng/L, by Sample
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
1
Target Not
Cone. Trant Tram
227
45.6
138
91.1
281
91.1
90.2
213
237
282 255
252 295
46.9 43.2
42.7 48.0
116 121
107 122
76.0 81.0
71.0 79.0
235 237
220 274
74.0 90.0
74.0 95.0
75.0 77.0
72.0 88.0
181 187
162 213
197 203
195 233
Trant
265
234
47.8
51.0
121
118
76.0
70.0
235
240
70.0
53.0
75.0
78.0
182
184
213
199
2
Not
Trant
301
249
54.0
53.0
128
124
78.0
78.0
250
260
69.0
60.0
82.0
86.0
195
200
207
200
Tram
331
358
56.0
55.0
121
124
76.0
78.0
214
215
58.0
65.0
75.0
72.0
193
197
183
188
3
Not
Trant
355
311
59.0
50.0
137
120
85.0
77.0
258
235
77.0
71.0
84.0
75.0
201
178
213
195
4
5
Not Not
Tram Tram Trant Trant
341
303
44.7
41.6
96.3
89.9
61.4
58.1
136
168
57.2
50.7
60.2
53.8
157
131
177
144
301
328
41.6
49.9
82.7
99.6
53.7
63.0
157
182
44.0
59.7
51.4
58.3
121
143
120
159
350
323
45.2
45.1
103
97.5
66.9
61.9
192
180
63.3
56.9
59.6
58.4
178
143
189
156
322
288
42.6
37.8
93.2
78.7
60.9
50.6
176
150
57.1
47.7
58.9
59.8
138
113
145
123
a Results for duplicate samples lor each treatment.
b Duplicate sample not analyzed.
Trans: sample transported.
Not trans: sample not transported.
TABLE 3-8(b). SUMMARY OF TRANSPORT STUDY RESULTS FOR HIGH SPIKED SAMPLES
Mean
Concentration
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1 ,2-dichloroethane
trichloroethene
tetrachloroethene
Trant
303.9
47.6
109.4
69.5
203.5
62.2
67.9
170.8
184.1
Not Trtnt
300.5
47.9
110.6
70.6
217.9
67.0
72.0
168.7
179.8
Standard Deviation
Tram Not Tram
43.6
4.9
12.2
7.2
33.9
8.4
8.8
21.8
20.6
32.0
6.6
20.3
12.4
46.6
16.8
13.6
36.6
39.9
Tram
14.3
10.3
11.2
10.3
16.7
13.5
13.0
12.7
11.2
%RSD
Not Tram
10.6
13.7
18.4
17.5
21.4
25.1
18.9
21.7
22.2
Mean
Trant
135.6
104.4
79.3
76.3
72.4
68.3
75.3
80.2
77.7
*R
Not Tram
II
132.4
105.1
80.2
77.5
77.5
73.5
79.9
79.2
75.9
Dltt. In
lean %R
1.5
0.7
0.9
1.2
5.1
5.2
4.6
1.0
1.8
Mean Concentration: Mean concentration for duplicate samples for five sample pairs.
%RSD: Prcent relative standard deviation.
Mean %ft: Mean percent recovery for duplicate samples for five sample pain.
Difference in mean %R: Difference in mean percent recovery between samples not transported and those transported.
37
-------
concentrations; however, responses for TCE and
PCE show some nonlinearity in the superhigh-con-
centration range. The elevated concentrations of
those compounds (in the TT, as well as in the
superhigh-concentration SPEW samples) required
use of the smallest sampling loop. One explana-
tion for this finding could be carryover of those
compounds in that loop.
Quality Assurance and Quality Control
Results
Results for QC Samples
QCCS Results: Percent Recoveries
Measured concentrations for the QCCS sam-
ples are shown in Tables 3-9(a,b). Percent recov-
ery results are presented in Tables 3-10(a,b).
Figure 3-4 shows QCCS %R results for each com-
pound for both the AVOAS and EMSL-LV.
Method 5022 With the exception of 1,1-
DCE, all but two (of 30) data points for the EMSL-
LV QCCS samples were within the DQO of 100
±30 %R. The theoretical spike value for 1,1-DCE
was 2.0 ug/L; five of the six %Rs for 1,1-DCE
were between 175 and 195%, or 3 to 4 ug/L. The
impact of the 1,1-DCE results in this demonstra-
tion was minimal. Two other results exceeded the
DQO: one for VC and one for 1,1,1-TCA.
AVOAS AVOAS results for VC were more
variable than those of EMSL-LV, with %Rs rang-
ing from 64-170%. Four of the six recoveries for
VC exceeded ±30 %R of the theoretical spiked
concentration. In contrast to the EMSL-LV results,
only one 1,1-DCE result exceeded ±30% of the tar-
get value. TCE, PCE, and 1,1,1-TCA each had one
value that exceeded ±30% of the target value.
For both EMSL-LV and the AVOAS, all com-
pounds (except 1,1,1-TCA for EMSL-LV) had
their highest %R on the first day of analysis. For
TABLE 3-9(8). QUALITY CONTROL CHECK STANDARD RESULTS FOR EMSL-LV
Detected Concentration, jig/L, by Day
Compound
vinyl chloride
1,1-dichloroethene
1,1,1-trichloroethane
trichloroethene
tetrachloroethene
Target Cone.
(ng/L)
20.0
2.0
10.0
2.0
15.0
1
27.2
3.9
10.0
1.9
16.7
2
22.6
3.6
7:9
1.6
13.7
3
23.9
3.9
9.0
1.8
15.1
4
25.0
3.6
10.1
1.8
14.8
5
25.3
3.5
8.4
1.6
13.7
6
21.4
2.4
6.5
1.8
14.0
Vean Cone.
(H9/L)
24.2
3.5
8.7
1.8
14.7
Summary
Standard
Deviation
2.1
0.6
1.4
0.1
1.2
%RSD
8.5
16.0
15.8
7.0
7.9
TABLE 3-9(b). QUALITY CONTROL CHECK STANDARD RESULTS FOR THE AVOAS
Datictid Concantratlon, (ig/L, by Day
Compound
vinyl chloride
1,1-dichloroethene
1,1,1-trichloroethane
trichloroethene
tetrachloroethene
Targat Cone.
(M9/M
20.0
2.0
10.0
2.0
15.0
1
33.9
2.3
15.2
5.4
18.3
2
29.8
1.7
11.4
2.1
13.9
3
12.8
1.1
8.0
1.4
9.6
4
15.9
1.4
7.2
1.4
10.9
5
25.6
1.7
9.2
1.9
11.9
6
27.7
1.9
10.8
2.3
14.1
Mean Cone.
(H9/M
24.3
1.7
10.3
2.4
13.1
Summary
Standard
Deviation
8.2
0.4
2.9
1.5
3.1
%RSD
33.8
24.4
28.1
61.9
23.3
%RSD: Percent relative standard deviation
Mean % R: Mean percent recovery.
38
-------
the following days, results for 1,1,1-TCA, TCE,
and PCE tended to be near or less than 100% R.
The cause for either of these observations is uncer-
tain.
QCCS Results: Precision
Method 502.2 Percent RSDs for EMSL-
LV analyses ranged from 7 to 16% among com-
pounds.
AVOAS For the AVOAS QCCS samples,
although the mean %Rs for each compound across
days were good (84 to 122%), the %RSDs tended
to be high, ranging from 23 to 62%. The 62 %RSD
for TCE is a result of an inexplicably high %R of
approximately 270% on the first day of analysis.
The variability for the EMSL-LV QCCS sam-
ples was notably less than that for the AVOAS,
probably because the QCCS used by EMSL-LV
was prepared from a single ampoule spiked into
reagent water, and the same solution was used for
the entire demonstration; for the QCCS used for
the AVOAS. A new ampoule was opened daily and
a fresh standard was prepared. As one would
expect, this procedure led to less variability in the
EMSL-LV results than those of the AVOAS for the
QCCS analyses. Variabilities in spiking technique
and in analyte concentrations in the commercially
prepared spiking solutions would be expected to
contribute to the lower precision values for the
AVOAS.
Surrogate Recoveries
A surrogate compound was not used for the
AVOAS analyses. Surrogate (2-bromo-l-chloro-
propane) recoveries ranged from 85 to 116%, all
within the 80 to 120% acceptance limits for
Method 502.2.
Instrument Blank Results
Method 5022 Instrument blanks showed
no analytes present at concentrations greater than
the MDLs.
AVOAS The blank samples run on the
AVOAS showed small amounts of one or more of
TABLE 3-10(a).
PERCENT RECOVERIES FOR QUALITY CONTROL CHECK STANDARDS
Percent Recovery, by
Compound
vinyl chloride
1,1-dichloroetherte
1,1,1-trichloroethane
trichloroethene
tetrachloroethene
1
136
195
100
95
111
2
113
180
79.0
80.0
91.3
3
120
195
90.0
90.0
101
4
125
180
101
90.0
98.7
Oiy
5
127
175
84.0
80.0
91.3
6
107
120
65.0
90.0
93.3
Hem
%R
121
174
86.5
87.5
97.8
FOR EMSL-
Summtry
Standard
Deviation
10.4
27.8
13.6
6.1
7.6
LV
%RSD
8.6
16.0
15.8
7.0
7.8
TABLE 3-1 0(b).
PERCENT RECOVERIES FOR QUALITY CONTROL CHECK STANDARDS
Percent Recovery, by
Compound
vinyl chloride
1,1-dichloroethene
1,1,1-trichloroethane
trichloroethene
tetrachloroethene
1
170
115
152
270
122
2
149
85.0
114
105
92.7
3
64.0
55.0
80.0
70.0
64.0
4
79.5
70.0
72.0
70.0
72.7
Diy
5
128
85.0
92.0
95.0
79.3
6
139
95.0
108
115
94.0
Mem
%R
122
84.2
103
121
87.5
FOR THE AVOAS
Summary
Standard
Deviation
41.3
20.6
28.8
75.3
20.5
%RSD
33.9
24.5
28.0
62.3
23.4
39
-------
the target analytes; however, with the exception of
PCE, all were at concentrations less than the MDL
or PQL of the instrument. The PQL for the 10-mL
sampling loop used for blanks was 0.10 (ig/L for
PCE; PCE was present in all blanks at approxi-
mately 0.3 to 1.2 \ig/L. However, because the low-
est sample concentration of PCE in this study was
15 |lg/L (in the QCCS), no data were invalidated
by the presence of the small amounts of PCE
detected in the blanks.
Travel Blank Results
Travel blank samples were not run for the
AVOAS, because samples were not shipped.
Quality Control Check Standard Results
VINYL CHLORIDE
Quality Control Check Standard Results
1,1-OICHLOROETHENE
200-]
150-
100-
50
200<
140-
100-
50
2 J DAY *
AVOAS
Quality Control Check Standard Results
1,1,1-TOCHLOROETHANE
DAY
AVOAS -«. EMSL-LV
Quality Control Check Standard Results
TRtCHLOROETHENB
200-|
150
100-
50
200-1
150-
100-
50 -*T
3 DAY *
-- AVOAS -*- EMSL-U
2 3 DAY *
-- AVOAS -e- EKSL-CV
Quality Control Check Standard Results
TETRACHLOROETHENE
200-1
150-
100-
50 JT
2 3 DAY *
HH AVOAS -O- BWH.V
Figure 3-4. Quality Control Check Standard Results.
40
-------
Travel blanks analyzed by EMSL-LV during the Continuing Calibration Check Standard
demonstration contained concentrations of PCE Results
below the MDL; 1,1,1-TCA was detected in one
aeck Standard results
no demonstration data were impacted by contami-
nation during transport.
TABLE 3-11(8). PERCENT DIFFERENCES
EMSL-LV
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
for EMSL-LV and the AVOAS are shown in Tables
3-ll(a,b).
FOR CONTINUING CALIBRATION CHECK STANDARDS
1
6.4
5.6
7.9
-8.2
9.6
14.8
8.3
10.6
14.4
2
0.7
2.3
2.6
1.0
2.7
7.1
2.0
1.1
3.2
Percent Difference,
3
5.8
6.4
4.4
4.8
4.9
5.6
4.3
1.1
3.2
byOiy
4
6.8
5.4
2.7
2.4
7.2
5.3
6.8
4.0
4.3
5
3.9
4.5
1.4
1.3
1.3
10.0
0.6
0.7
0.2
FOR
6
0.85
0.30
7.1
6.2
2.6
12.7
-2.2
3.8
6.3
TABLE 3-11(b). PERCENT DIFFERENCES
AVOAS
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
FOR CONTINUING CALIBRATION CHECK STANDARDS
1
8.3
2.3
6.4
8.6
-7.0
-20.1
3.6
10.2
7.5
2
28.4
16.3
-0.18
-5.6
3.3
13.6
1.7
5.9
4.0
Percent Difference,
3
10.7
9.9
9.3
9.1
6.2
22.9
1.9
10.8
8.3
byDiy
4
35.5
21.6
3.1
4.0
2.0
7.4
1.5
6.2
5.8
5
30.5
24.9
1.2
7.8
5.5
18.8
2.9
9.9
6.8
FOR THE
6
24.9
21.2
6.8
13.2
11.8
30.1
9.5
16.4
18.6
Percent Difference * C,-C2 100/C,; C, = response for initial calibration; C2 a response for continuing calibration.
EMSL-LV data are the mean of two measurements.
Target concentrations for all analytes lor EMSL-LV were 20 fig/L, and for the AVOAS, 400 (ig/L.
41
-------
Method 502.2 All %Ds for the EMSL-LV
CCCSs were within the acceptance criteria of <20
%D. The EMSL-LV instrument was recalibrated
once, on the second day of the demonstration
because %Ds of nearly 15% were noted for two
compounds on the first day. All EMSL-LV sam-
ples were analyzed within acceptable instrument
calibration.
AVOAS Over the 6 days of analysis, 10 of
54 of the %Ds for individual analytes were >20%.
These high %Ds occurred with three compounds:
VC, 1,1-DCE, and 1,1,1-TCA. Two of the VC
responses exceeded 30 %D. If the data associated
with those two CCCSs are considered suspect, 10
of the 30 spiked sample results would be invalid.
Most of these are for VC, for which the majority of
QCCS and SPEW samples had %Rs in excess of
100 ±30%.
Results for Data Quality Objectives
Representativeness
To determine whether or not the data from
spiked samples introduced into the AVOAS in the
off-line mode were representative of data obtained
when the instrument was operated in the automated
mode, the results for AVOAS on-line and off-line
TT samples were compared. Vinyl chloride and
1,2-DCA were not detected by the AVOAS or
EMSL-LV in the TT samples. Of the remaining
seven analytes, the difference between the on-line
and off-line AVOAS results was not significant or
only slightly significant for most compounds. The
TT sample results indicate that data generated
using off-line spiked samples should be representa-
tive of data generated by the AVOAS in an on-line,
automated mode.
Completeness
The QC data for the EMSL-LV instrument
indicated acceptable conditions for all measure-
ments. For the AVOAS, although data in excess of
the QC limits occurred, no statistical outliers were
identified. All of the AVOAS data values were uti-
lized in performing the statistical tests and in
developing the conclusions for this demonstra-
tion. Completeness is therefore considered to be
100%.
Accuracy
Comparisons of accuracy results for the
AVOAS and EMSL-LV were made using %R data
for QCCS and SPEW samples. The QCCS data
were discussed previously and are summarized in
Table 3-10(a,b).
SPEW sample differences in mean %R
results were discussed previously. Percent recov-
eries for individual days are presented in Tables 3-
12(a,b). A total of 210 %Rs for SPEW samples
were collected on each of the instruments.
Method 5022 Percent recoveries ranged
from 48 to 122%, with no results above the limit
and 39% of the results below 70 %R.
AVOAS Fourteen percent of the AVOAS
SPEW sample results were in excess of ±30% of
the target concentrations; recoveries for those sam-
ples were all greater than 100%. Only three of the
24 VC recoveries were within 100 ±30 %R. Ana-
lytes other than VC with %Rs that exceeded 100
±30% included 1,2-DCA, 1,1,1-TCA, TCE, and
PCE. With the exception of VC, virtually all of the
analyte results were within a 100 ±50 %R window.
Precision
Precision for TT and SPEW sample results
was discussed earlier. Precision for AVOAS and.
EMSL-LV QCCS sample results are not compara-
ble because of the different QCCS preparation pro-
cedures used.
Comparability
Results concerning the comparability of the
AVOAS and Method 502.2 were discussed previ-
ously in the sections on TT, SPEW, and QCCS
sample results.
Performance and Systems Audits
Performance audits use samples spiked with
known concentrations of analytes to quantitatively
evaluate the measurement capability of a system.
No samples were specifically designated as perfor-
mance audits in this demonstration, because many
of the samples were inherently similar to perfor-
mance audit samples. That is, they were samples
spiked with known concentrations of target ana-
lytes.
Systems audits are qualitative evaluations of
operational details, performed to ensure that the
protocols of the QAPjP are properly imple-
mented. Systems audits were conducted at both
the EMSL-LV laboratory and the Wobum site early
in the demonstration by experienced QA auditors
from LESC. Facilities, equipment, and operations
(such as sample collection and handling, record-
42
-------
keeping, chain-of-custody and sample tracking,
data reporting, and QA procedures) were audited.
The EMSL-LV audit indicated satisfactory condi-
tions and compliance with the QAPjP. For the field
site, no serious problems were found. The absence
of written operating procedures for the AVOAS
was noted. Also, high variability in the early
QCCS results for the AVOAS was observed; how-
ever, it was too early in the study to determine the
significance of or to identify a cause for that find-
ing.
Qualitative Observations
The short duration of this demonstration did
not permit a comprehensive qualitative evaluation
of the AVOAS. However, several observations
regarding system features were made incidental to
the field demonstration and these are summarized
below.
Ruggedness and Adaptability
The AVOAS hardware is well-designed and
ruggedly constructed. The system is sturdy and
without extraneous frills or packaging. The basic
components are visible and accessible, facilitating
maintenance and troubleshooting. The AVOAS
components are designed to accommodate field-
automated analyses: the stripping cell is self-
cleaning between sampling events', sample port
and sample volume can be automatically or manu-
TABLE 3-1 2(a). PERCENT RECOVERIES FOR SPIKED PURGED EFFLUENT WATER SAMPLES FOR EACH
DEMONSTRATION DAY FOR EMSLV
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dich!oroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,2-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
1
92.9
87.7
71.9
71.4
76.6
61.5
78.7
76.5
80.2
1
107.0
92.1
76.3
74.6
79.5
67.0
80.9
80.7
83.6
2
89.7
87.7
71.9
73.5
76.6
71.4
76.5
78.3
81.6
2
79.2
66.2
57.4
59.3
60.2
68.1
66.5
66.6
66.7
Low
3
47.8
61.4
53.8
56.0
61.3
56.0
67.6
61.9
64.6
High
3
76.2
71.7
59.6
60.4
62.0
58.2
63.2
63.8
64.8
Spikl
4
92.0
85.5
71.2
71.4
74.5
67.0
75.4
75.0
76.0
Split*
4
104.0
88.2
74.1
75.7
76.3
71.4
79.8
74.6
76.0
Medium Spike
5
96.4
92.1
74.9
76.8
81.6
77.9
86.5
86.3
87.8
6
90.2
109.6
71.2
73.5
74.5
122.9
74.3
75.5
83.2
1 2
104.0 78.9
73.5 60.4
77.9 67.7
86.4 83.8
86.5 81.0
81.2 73.5
84.4 85.7
75.3 75.5
84.6 74.4
3
70.1
58.2
63.6
78.9
75.5
68.1
82.1
71.0
71.0
4
74.9
53.7
58.5
72.1
68.4
63.7
73.7
64.3
62.0
5
90.6
63.7
62.6
75.7
70.5
68.1
71.7
65.6
63.1
6
72.2
48.6
53.3
64.5
59.9
65.9
68.6
55.8
52.7
Super High Spike
5
120.7
103.5
90.1
88.9
87.3
94.4
87.6
87.7
86.1
6
102.2
84.9
69.8
68.1
68.4
75.7
73.2
69.9
68.4
1 2
77.8 68.3
i a
68.3 63.7
79.0 74.6
73.9 65.3
70.3 69.7
82.5 73.6
75.9 68.4
82.3 69.9
3
77.6
a
60.1
68.1
61.2
71.9
67.3
64.7
78.4
4
60.2
a
49.8
59.3
55.9
59.3
62.6
55.3
57.5
5
97.7
a
68.9
76.8
65.5
75.7
72.3
70.3
73.8
(
343
i
622
79.0
70.4
70.3
69.8
67.5
67.6
1,1-dicMonethene was not spiked into superhigh-concentration spiked purged effluent water samples.
43
-------
ally selected; and the system can be adapted to dif-
ferent purgeable analytes by using the appropriate
GC column, temperature program, and detector.
Maintenance Requirements
The maintenance requirements of this instru-
ment are similar to those for other analytical instru-
mentation. Routine GC maintenance procedures
are required, e.g., changing gas cylinders, cleaning
detectors, and replenishing integrator paper. Sys-
tem-specific maintenance includes cleaning or
changing the inlet water filters to the injector
(about once a day); changing the peristaltic pump
tubes on the injector (about once a week); and
changing the drying trap on the injector (about
once a week). These routine maintenance proce-
dures do not appear to be time-consuming or diffi-
cult
According to the AVOAS developer, they can
be completed in less than 15 min and can be done
at the time of the continuing calibration check.
Facility and Supplies Requirements
The AVOAS requires an environment consis-
tent with that found in an analytical laboratory: a
sturdy bench or tabletop (approximately 80 x 30
in), a clean source of water, constant temperature
(ideally 20°C, ± 3°C), and a relatively clean, VOC-
free environment If telecommunications are
desired, a dedicated telephone line is necessary.
The instrument is not suitable for quick setup in a
harsh environment (e.g., as required for emer-
TABLE 3-12(b). PERCENT RECOVERIES FOR SPIKED PURGED EFFLUENT WATER SAMPLES FOR EACH
DEMONSTRATION DAY FOR THE AVOAS
Low Spiki
Compound
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
1
145.7
97.8
96.3
101.3
96.5
95.9
97.6
96.0
92,0
2
164.3
98.0
99.1
104.5
101.3
104.1
97.1
104.0
98.4
3
125.1
82.5
86.9
95.5
93.9
93.9
93.4
92.1
88.9
4
135.4
94.5
74.1
95.1
97.9
104.5
98.8
93.4
90.7
5
141.1
91.9
78.4
103.7
106.7
114.4
106.2
100.8
93.2
6
142.9
98.2
99.0
106.7
97.3
189.5
102.5
105.6
104.7
1 2
160.9 151.3
82.3 79.0
100.6 102.1
122.4 117.6
107.4 105.7
120.6 118.0
116.0 108.2
104.9 106.3
99.9 101.2
High Splk*
vinyl chloride
1,1-dichloroethene
trans-1,2-dichloroethene .
1,1-dichloroethane
cis-1,2-dichloroethene
1,1,1-trichloroethane
1,2-dichloroethane
trichloroethene
tetrachloroethene
1
146.1
97.7
95.7
98.7
95.0
94.4
95.4
97.3
96.3
2
157.0
101.1
97.8
98.5
96.3
96.0
91.6
102.0
98.2
3
118.3
87.3
85.8
91.8
88.3
89.5
88.2
93.0
91.2
4
130.7
89.7
82.8
88.5
77.3
75.8
76.4
80.2
79.7
5
132.5
103.0
74.6
102.6
101.6
110.3
102.9
103.2
98.9
6
136.7
103.7
98.1
98.9
94.4
97.8
99.0
104.2
105.7 .
1 2
162.1 138.9
a a
104.0 100.4
121.7 106.4
117.1 104.7
130.0 102.1
114.0 99.5
119.7 114.3
125.5 120.0
Medium Spike
3
138.4
74.5
93.2
114.5
97.7
114.0
102.0
94.9
92.8
4
92.8
47.4
62.1
75.4
63.8
69.1
71.5
63.4
58.9
5
145.7
78.0
72.9
117.0
99.2
106.9
111.3
96.5
90.4
6
155.0
76.8
99.6
120.4
100.8
123.1
108.6
103.4
102.9
Superhlgh Spike
3
151.4
a
93.7
104.1
97.5
106.8
100.0
105.6
108.7
4
124.5
a
90.1
96.7
92.0
92.0
87.1
100.4
110.4
5
163.1
a
97.5
103.7
99.1
108.3
94.8
105.1
109.1
6
189.4
a
108.6
121.9
114.5
136.9
121.2
124.1
138.1
/, 1-dichloroethene not spiked into superhigh-concentration spiked purged effluent water samples.
44
-------
gency-response screening analyses), but is
designed for long-term monitoring in an undis-
turbed location. A constant 20-A, 120-V power
source is required. Any extended interruptions in
power require a warmup time to ensure that the
detection system has reached a stable equilibrium.
After a power interruption, a calibration check is
required to ensure that the system instrument has
not changed.
A water supply is required for flushing the
lines and sample loops between analyses. The
AVOAS includes a sparging system that uses high-
purity inert gas to purge a water source of VOCs.
At most sites, local tapwater could be used as a
source for rinse-water. Otherwise, bottled purified
water can be used.
The instrument should be operated in a con-
stant-temperature environment because a fluctua-
tion of more than a few degrees would probably
alter the sparging efficiencies of the target volatile
analytes. This situation was not encountered or
studied during the demonstration.
Provision must be made for treatment and
disposal of waste water generated by the AVOAS
during its operation. Several liters of treatment
train water (500 mL/min for several minutes) are
generated during sampling. The amount depends
on the length of the sampling lines. At the Wobum
site, the contaminated waste water was collected
and recycled into the treatment system, so waste
water disposal was not a problem.
In addition to compressed gases used to oper-
ate the GC, the AVOAS requires zero-grade helium
for the injector purge gas, and standard-grade
helium for the rinse-water purification system.
Other supplies are the same as those required for
standard GC analyses of VOCs in water.
System Costs
The AVOAS is currently not for sale. The
developer intends to initially lease AVOAS units at
rates that will depend upon the specific system
configuration; a one-time fee for system setup and
operator training will be charged. An additional
expense in using the AVOAS would be that for an
operator. Although an operator was present for
about 14 hr/day during the demonstration, during
routine monitoring, an operator's presence would
be required for at most 1 hr/day.
The AVOAS was leased at the Wells G and H
Superfund Site for $8000 per month. Assuming
that 20 samples/day could be processed under rou-
tine monitoring operations (not including QC sam-
ples), the cost per sample over a month would be
less than $15, not including operator labor cost.
The cost per sample for comparable analysis by
conventional methods is approximately $225-275,
depending on the method used and the number of
target analytes. However, because of sample turn-
around time (usually on the order of several days),
conventional methods are not typically suited to
high-frequency, long-term monitoring, so the costs
may not be directly comparable.
Summary of Results and Discussion
1. For most of the TT samples, concentrations
measured by the AVOAS in the on-line mode
were slightly higher than those measured off-
line; however, the difference was not significant
for most compounds. This indicated that the
findings for samples analyzed off-line (e.g.,
SPEW and QCCS samples) could be considered
representative of on-line performance, and
could be used for comparisons of the AVOAS
and EMSL-LV results.
2. Nearly all recoveries for both TT and SPEW
samples were higher for the AVOAS than for the
EMSL-LV analyses. However, the overall mean
%R for EMSL-LV (for all compounds, concen-
tration ranges, and days) for SPEW samples was
74%, in comparison to 104% for the AVOAS.
These findings seem to indicate that the AVOAS
gave results more nearly equivalent to the target
concentrations than EMSL-LV. QCCS %R
results for EMSL-LV close to 100% and CCCS
results consistently within acceptable ranges
would seem to argue against a problem in instru-
ment calibration. Transport or holding time
effects are a possible explanation for the finding
of lower EMSL-LV analyte concentrations.
3. The effect of transport on sample results is open
to question. The variability due to analyst
appears to exceed that due to transport.
4. Treatment train samples analyzed by the
AVOAS in the afternoon had slightly higher
analyte concentrations than those analyzed in
the morning, especially for the less volatile
compounds. This finding is consistent with car-
ryover from superhigh-concentration SPEW
samples analyzed between the morning and the
afternoon. Both TT and superhigh-SPEW sam-
ples were collected through the smallest sam-
pling loop. The increases in concentration are,
however, low enough to be of no practical sig-
nificance.
45
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5. AVOAS %R results for vinyl chloride were van-.
able and substantially exceeded those for other
compounds analyzed by that system, and they
were proportionately higher than those of the
EMSL-LV analyses. The source of the problem
cannot be determined from the demonstration
data. If the AVOAS were considered for use at a
site having vinyl chloride as a contaminant, the
system's performance in measuring that com-
pound would need to be more rigorously evalu-
ated.
The question of false-positive results arises
with respect to compounds detected by the AVOAS
but not by EMSL-LV in the TT samples. In all of
the sample pairs for which the AVOAS had detect-
able concentrations of compounds but EMSL-LV
did not, the concentrations measured by the
AVOAS were less than the detection limits for the
EMSL-LV instrument Thus, it is unlikely that the
AVOAS results reflect false positives.
Although false-negative results (i.e., not
detecting a contaminant when in fact it is present)
were not studied in this evaluation, such erroneous
results are possible, and steps should be taken to
minimize them. The consequence of a false-nega-
tive result could be to not recognize a failure or
decline in function of some component in the treat-
ment system. False-negative results could poten-
tially occur if there were a problem in either the
sampling or the analytical system; for example, if a
sampling line were clogged or if the manifold were
not functioning properly. Ongoing instrument cali-
bration checks are important, as are confirmatory
analyses, particularly of samples from effluent
ports, where the risk of actual VOC concentrations
exceeding measured values is of most concern; i.e.,
where the potential exists for releasing water con-
taining VOC concentrations above the allowable
effluent limits.
The data from this study were also evaluated
by Stanley Deming and John Palasota, of the Uni-
versity of Houston Department of Chemistry under
a cooperative agreement with the EMSL-LV. Their
findings are summarized in a technical report sub-
mitted to the EPA through a cooperative agree-
ment. Although their approach to data analysis
was somewhat different (i.e., ratios of paired data
rather than differences in mean %Rs were evalu-
ated), the findings were similar. That is, the
AVOAS gave results that were comparable to those
obtained using Method 502.2. Bias exists; the
AVOAS results are high compared to the EMSL-
LV results. The source for this bias is not possible
to determine from the data of this study. Possible
explanations could include calibration differences
between the two locations or degradation of sam-
ples due to sample shipment and holding time. The
QC data do not indicate a calibration problem, and
the potential for a holding time effect is not sup-
ported by the TT sample data or the transport study
results. Whether bias would occur in general (i.e.,
for routine use of the AVOAS) is yet to be learned.
An interpretation of the data from this dem-
onstration, and any extension of the results to other
similar evaluations, must be tempered by several
considerations. Throughout the demonstration the
AVOAS was being operated by its inventor, who
was there daily monitoring and adjusting its perfor-
mance. Also, the demonstration was conducted
shortly after the system was installed, so that any
long-term effects, such as loss in performance due
to wear and tear on the system or contamination of
its various components (e.g., sampling Ones, mani-
fold, sampling loops, sparging unit) could not be
evaluated.
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Section 4
Conclusions and Recommendations
Conclusions
The AVOAS demonstration went smoothly,
and was considered by both the AVOAS developer
and EMSL-LV to be a fair evaluation of its perfor-
mance under the study conditions. All samples
specified by the demonstration design were ana-
lyzed, and all of the data were judged to be of suffi-
cient quality to be included in the data base upon
which the following conclusions for this demon-
stration are made. The qualitative and quantitative
findings generated in this demonstration provided
the basis for the following conclusions regarding
the performance of the AVOAS:
1. Mean concentration values generated by the
AVOAS for all analytes in all SPEW and TT
treatment train samples were higher than those
measured by Method 502.2. The cause of this
bias is difficult to determine from the data avail-
able. The bias is more likely due to sample
holding time and/or transportation effects, ana-
lyst techniques for calibration, preparing spiked
samples, or analysis, or some combination of
these, than to the instrument itself.
2. The precision obtained by the AVOAS was com-
parable to that obtained by the laboratory instru-
ment, within the range of expected variability
for samples containing VOCs.
3. The AVOAS performed well in analyzing sam-
ples with VOC concentrations in the low-ppb to
ppm range.
4. The system used by the AVOAS for stripping
VOCs from water (one of the proprietary fea-
tures of the AVOAS) is simple in design and
function, self-cleaning, and more adaptable to
field automation than the traditional purge-and-
trap procedure.
5. The fact that the AVOAS was operational
shortly after installation, and was running nearly
24 hours per day for the duration of this demon-
stration indicates the potential reliability of the
system is high.
6. Based on the findings of this demonstration, the
AVOAS appears to have the potential to provide
data comparable to that which would be
obtained using established sampling and analyti-
cal methods. The discrepancies in accuracy and
precision are not substantial enough to offset the
advantages of the system and are probably
attributable factors other than instrument perfor-
mance.
Advantages of the AVOAS
1. The AVOAS is simple in design, and has easily
accessible components. The LESC scientist
present at the field site observed that the minor
instrumental problems encountered during the 6
days of analysis were relatively easy to diagnose
and repair.
2. The AVOAS appears to be capable of providing
the benefits of automated sampling and analysis
discussed in Section 1 of this report; i.e., rapid
results and the elimination of separate sample
collection, handling, shipping, and analysis
steps.
3. The potential cost savings per sample for use of
the AVOAS in comparison to use of established
methods could be substantial. Savings would be
realized not only in the activities related to sam-
pling and analysis, but in the increased effi-
ciency brought about by real-time monitoring of
the performance of ground-water treatment sys-
tems. We must emphasize that, with a dedi-
cated, on-line system, sampling frequency
would probably be greater than if conventional
methods were used. For that reason, the cost per
sample would be lower. In addition, the likeli-
hood of detecting a change in system perfor-
mance would be increased.
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Limitations of the AVOAS
Although the following items were identified
as potential limitations to the AVOAS, many of
them are merely factors to be kept in mind by pro-
spective users of the AVOAS. The AVOAS devel-
oper has since taken steps to correct equipment or
procedural problems.
1. The AVOAS requires a temperature-controlled
environment in an atmosphere free of contami-
nation. Extra measures to ensure these condi-
tions may be required in a typical field situation
or industrial facility.
2. Water samples high in paniculate matter tend to
clog a filter in the injector inlet This problem
can be minimized if water is pre-filtered before
being conveyed to the AVOAS or if the inlet fil-
ters are cleaned or changed as part of the routine
daily maintenance.
3. Internal standards cannot be analyzed by the
AVOAS in the on-line mode. Such standards
provide an ongoing indication of instrument per-
formance. It is possible to indirectly monitor
instrument performance through calibration
checks and observation of analyte concentra-
tions for each port However, this approach is
not recommended, and is not diagnostic for
problems with the analytical versus the sam-
pling and sparging portions of the system.
4. Carryover in the smallest sample loop of the
AVOAS was suggested by the finding of an
increase in trace concentrations of several ana-
lytes in TT samples between the morning and
afternoon analyses. The corresponding EMSL-
LV data do not reflect these findings. Because
of the low concentrations involved, the possibil-
ity of carryover is not a serious impediment to
use of the AVOAS for higher concentration ana-
lytes. The AVOAS developer has modified the
design of the manifold to reduce dead volume
significantly, and expects this change to greatly
reduce the carryover problem.
5. The volume of sample injected by the smallest
sampling loop was difficult to measure accu-
rately because the dead volume of the sample
valve (i.e., the internal volume of valve parts,
aside from sample volume measurement hard-
ware) was disproportionately large. The devel-
oper is examining better approaches to
estimating volumes for each of the sampling
loops.
6. Most of the problems, albeit minor, encountered
with the AVOAS during the field demonstration
were due to problems in the software. Some
were solved during the demonstration, and plans
were made to correct the others shortly after the
demonstration was completed.
Limitations of the AVOAS Demonstration
This demonstration was designed to evaluate
specific aspects of the AVOAS performance rela-
tive to an established method; the demonstration
was not a comprehensive evaluation of all of the
proposed advantages or potential limitations of the
system. The conditions of this demonstration were
atypical of those that would probably exist under
routine monitoring operations. A number of sam-
ple types were analyzed in the off-line mode and
the demonstration was performed with the AVOAS
inventor closely checking and adjusting the sys-
tem's performance. The capability of the AVOAS
to be operated unattended from a remote location
under software control was not evaluated; nor
were the repeatability and reliability of calibration
and maintenance procedures, or the long-term per-
formance of the system.
Recommendations
Recommendations are made here specifically
for the AVOAS and for future SITE Program dem-
onstrations. A number of the issues encountered for
the AVOAS demonstration design apply to the
demonstration of virtually any technology. Reso-
lution of these issues would facilitate collection of
high quality data for future SITE demonstrations.
Recommendations Specific to the AVOAS
1. Further development of the AVOAS is encour-
aged. A fair evaluation at a future stage of
development would require monitoring the sys-
tem's performance when operated totally in the
automated mode, without interruption or inter-
vention. Performance data should be generated
for this system when used at other sites and by
different operators.
2. Instrument calibration should be checked regu-
larly, on a schedule based on the performance of
the detector. A daily calibration check is recom-
mended. If this is not feasible, at a minimum,
detector performance should be monitored daily
over a period of several weeks after instrument
installation. An appropriate calibration schedule
should be developed and followed for the long-
48
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term use of the system, especially for unat-
tended, remote operation.
3. A mechanism for introducing surrogate or inter-
nal standards into the AVOAS with each analy-
sis would provide an ongoing indication of
analytical instrument performance.
4. Depending on the data quality objectives for
instrument performance at a particular site,
blank samples should be periodically analyzed
on all sampling loops used for analysis to ensure
that carryover from high-concentration into low
concentration samples is not occurring.
5. In this demonstration, response factors for three
of the sampling loops were based on estimated
loop sizes. Errors in estimating the sample loop
sizes are thought to have influenced the calcu-
lated response factors for some of the loops, par-
ticularly the smallest size. A procedure for more
accurately determining sample loop size should
be developed. Alternatively, each sample loop
should be individually calibrated.
6. During the initial stages of long-term monitor-
ing, concentrations and precision for each sam-
pling port should be closely monitored to
generate baseline conditions. Also, periodic
confirmatory analyses by established methods
should be performed to verify AVOAS results.
7. An instruction and procedural manual for the
system should be written. QA/QC procedures
should be included as part of the standard oper-
ating procedures.
Recommendations for Future Studies
1. A more rigorous evaluation of holding time and
transport effects on measured concentrations of
VOCs in water samples is recommended.
2. An investigation of the stripping efficiency for
various VOCs from water, in purge and trap and
similar processes (e.g., the method used by the
AVOAS), for samples of different concentra-
tions and volumes is recommended.
3. A study to distinguish the variability due to cali-
bration-standard spiking procedures of various
analysts from the variability due to instrument
performance is recommended.
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