Guidance on the Documentation and Evaluation of
Trace Metals Data Collected for
Clean Water Act Compliance Monitoring
Draft
July 1996
U.S. Environmental Protection Agency
Office of Water
Office of Science and Technology
Engineering and Analysis Division (4303)
401 M St. SW
Washington, DC 20460
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Acknowledgments
This guidance was prepared under the direction of William A. Telliard of the Engineering
and Analysis Division (BAD) within the U.S. Environmental Protection Agency's (EPA)
Office of Water (OW), Engineering and Analysis Division (BAD). This guidance was
prepared under EPA Contract 68-C3-0037 by the DynCorp Environmental Programs
Division with assistance from Interface, Inc.
Disclaimer
This document has been reviewed and approved for publication by the Analytical Methods
Staff within the Engineering and Analysis Division of the EPA Office of Water. Mention
of trade names or commercial products does not constitute endorsement or recommendation
for use.
Further Information
For further information, contact:
William A. Telliard, Chief
Analytical Methods Staff
Engineering and Analysis Division
U.S. Environmental Protection Agency
401 M Street
Washington, DC 20460
Phone: 202-260-7134
Fax: 202-260-7185
Requests for additional copies should be directed to:
US EPA NCEPI
11029 Kenwood Road
Cincinnati, OH 45242
513-489-8190
Draft, July 1996
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Chapter 1
Introduction
Numerous organizations, such as state pollution control agencies, health departments,
local government agencies, industrial dischargers, research facilities, and federal agencies (e.g.,
EPA, USGS), collect data on effluent and ambient metal concentrations for use in a variety
of applications, including: determining attainment status for water quality standards,
discerning trends in water quality, estimating effluent concentrations and variability,
estimating background loads for total maximum daily loads (TMDLs), assessing permit
compliance, and conducting research1. The quality of data used is an important issue, and,
in particular, the quality of trace level metals data may be compromised due to contamination
during sampling, filtration, storage, and analysis. In fact, one of the greatest obstacles faced
by laboratories attempting trace metals determinations is the potential for contamination of
samples during the sampling and analytical processes. Trace metals are ubiquitous in the
environment, and samples can readily become contaminated by numerous sources, including:
metallic or metal-containing labware, metal-containing reagents, or metallic sampling
equipment; improperly cleaned and stored equipment; and atmospheric inputs such as dirt,
dust, or other participates from exhaust or corroded structures.
The measurement of trace metals at EPA water quality criteria (WQC) levels has been
spurred by increased emphasis on a water quality-based approach to the control of toxic
pollutants. Current ambient WQC levels2 for trace metals require measurement capabilities
at levels as much as 280 times lower than those levels required to support technology-based
controls or achievable by routine analyses in environmental laboratories. Also, recent USGS
and EPA studies strongly indicate that rigorous steps must be taken in order to preclude
contamination during the collection and analysis of samples for trace metals.
In order to ensure that the data collected for trace metals determinations at ambient
water quality criteria levels are valid and not a result of contamination, rigorous quality
control (QC) must be applied to all sample collection, preparation, and analysis activities.
EPA has published analytical methods (1983, 1991) for monitoring metals in waters and
wastewaters, but these methods are inadequate for the determination of ambient
concentrations of metals in ambient waters due to the lack of some or all of the essential
quality control and handling criteria. This prompted the Engineering and Analysis Division
(BAD) to develop new sampling and analytical methods that include the rigorous sample
handling and quality control procedures necessary to deliver verifiable data at WQC levels.
The new sampling method is entitled, Method 1669: Sampling Ambient Water for Determination of Trace
Metals at EPA Water Quality Criteria Levels ("Method 1669"). The new analytical methods include
Methods 1631, 1632, 1636, 1637, 1638, 1639, and 1640 ("the 1600 Series Analysis Methods").
Many of these analysis methods were developed by supplementing existing EPA methods
Prothro, M., Acting Assistant Administrator for Water, Memorandum to Water Management Division Directors and
Knvironmental Services Division Directors, Oct. 1, 1993.
"Water Quality Standards; Establishment of Numeric Criteria for Priority Toxic Pollutants; States' Compliance" (also referred to
as "The National Toxics Rule"), 40 CFR Part 131, (57 PR 60848, December 22,1992), and Stay of Federal Water Quality Criteria
for Metals, 40 CFR Part 131 (60 PR 22228).
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with additional quality control and sample handling requirements; others are new methods
that are based on newly developed analytical procedures.
Appropriate quality assurance (QA) and quality control (QC) procedures are the key
to producing precise and accurate data unbiased by contamination. Examination of trace
metals data without data from blanks and other QC analyses yields little or no information
on whether sample data are reliable. Data quality must be documented through the use of
blanks (both field and laboratory blanks), standards, matrix spike/matrix spike duplicates,
and field duplicates, as well as other QC analyses. The results of all QC procedures must be
included in the data reporting package along with the sample results if data quality is to be
known.
The remainder of this document contains guidance that is intended to aid in the
review of trace metals data submitted for compliance monitoring purposes under the
National Pollutant Discharge Elimination System (NPDES) when these data are collected
in accordance with Method 1669 and analyzed by the 1600 Series Analysis Methods. Chapter
2 of this document outlines the data elements that must be reported by laboratories and
permittees so that EPA reviewers can validate the data. Chapter 3 provides guidance
concerning the review of data collected and reported in accordance with Chapter 2. Chapter
4 provides a Data Inspection Checklist that can be used to standardize procedures for documenting
the findings of each data inspection.
The guidance provided in these chapters is similar in principle to the data reporting
and review guidance provided in EPA's Guidance on Evaluation, Resolution, and Documentation of Analytical
Problems Associated with Compliance Monitoring (EPA 821-B-93-001), but has been specifically adapted
to reflect particular concerns related to the evaluation of data for trace metals.
This guidance is applicable to the examination of recently gathered trace metals data
and to historical data in existing EPA databases. It should be noted, however that some
qualification of historical data may be required before these data can be included in current
databases. A draft User's Guide to the Quality Assurance/Quality Control Evaluation Scale of Historical Datasets
(12/20/90, available from EPA EMSL-LV), provides guidance that may be used to qualify
data for inclusion into current databases. This EMSL-LV guidance stipulates that at least
some form of QA/QC must be associated with the historical data for evaluation. This
QA/QC may be in the form of various types of blanks (method, field, etc.), replicates field,
analytical, etc.), spikes (matrix, surrogate internal standard, etc.), and PE samples (certified
reference materials, QC check samples etc.). A scoring mechanism is applied to these
QA/QC data, and the usability of the sample data is based on the resulting score.
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Chapter 2
Checklist of Laboratory Data Required
to Support Compliance Monitoring for Trace Metals
Determined in Accordance with Method 1669
and the 1600 Series Analysis Methods
The items listed below describe the minimum data elements necessary to validate trace
metals data collected using the Method for Sampling Ambient Water for Determination of Thrace Metals at EPA
Water Quality Criteria Levels (Method 1669) and the 1600 Series Analysis Methods. It should be
noted that since different instrumentation yields different data output, the specific form of
the data will vary according to the analytical method.
1. Method Number
The method number of the EPA analytical method used in conjunction with Method
1669 must be provided. This information will allow a data reviewer and user to become
familiar with the method, if necessary, prior to reviewing the data. It will also assist the
reviewer and user in making any necessary determinations of the comparability of these data
with previously reported data, including qualified historical data. If more than one method
is needed to cover a complement of analytes, then all method numbers must be provided.
A clear delineation of the specific method used for each given analyte is required. Also, the
revision date or revision level and number/letter of the method must be given, so that the
reviewer or user tests the results submitted against the specific method used. Table 1
provides a list of EPA methods for analysis of trace metals along with the corresponding
water quality criterion published by EPA for each metal or metal species.
In recognition of advances that are occurring in analytical technology, the 1600 Series
Analysis Methods are performance-based. That is, an alternate procedure or technique may
be used if the performance requirements in the reference method(s) are met. The analyst
must start with one of the methods as a reference, and may improve upon this reference
method to reduce interferences or lower costs of measurements. Examples include using
alternate chelating or ion exchange resins, alternate matrix modifiers, additional cleanup
techniques, or more sensitive detectors. The objective of allowing method modifications is
to improve method performance on the sample being analyzed. At no time are changes that
degrade method performance allowed. Each method details the tests and documentation
that are required to support equivalent performance.
2. Detailed Narrative
A detailed narrative discussing any problems with the analysis, corrective actions
taken, and changes made to the reference method must be included in a complete data
reporting package. Reasons for changes to the reference method, supporting logic behind
the technical approach to the change, and the result of the change must be included in the
narrative. The narrative should be written by an analytical chemist in terms that another
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analytical chemist can understand. The results of the review must be written so that the data
user can understand the reason(s) for acceptance/rejection of the data or any changes to the
reference method.
3. Data Reporting Forms
The complete data reporting package must include data reporting forms that list all
samples analyzed, the metals and metal species determined, and the concentrations found.
Analytes detected in field samples at concentrations below the minimum level (ML) must be
reported as non-detect. However, all analyte concentrations detected in blank samples must be
reported, regardless of the level. Results must be listed for each sample analyzed, including
any dilutions and reanalyses. Metals should be listed by name and CAS Registry number.
The ML is the quantitation level as defined by the EPA 1600 series method used for
sample analysis. The laboratory is required to determine the MDL for each analyte in
accordance with the procedures described in 40 CFK Part 136, Appendix B- Definition and
Procedure for Determination of Method Detection Limit - Revision 1.11. That MDL multiplied by 3.18 must be
less than or equal to the ML given in the EPA 1600 Series Analysis Method.
The use of data qualifiers or flags by the laboratory is discouraged. Rather,
laboratories should attempt to correct all analytical problems and provide a detailed narrative
that thoroughly describes those problems and the corrective actions taken (see item 2 above).
Flags or data qualifiers should be assigned by data users to reflect their specific data quality
objectives and uses of the data. If the laboratory submits data with internally generated flags,
the laboratory must provide an explanation of the meaning of the flags used.
4. Summary of Quality Control Results
Results for all quality control analyses required by the reference EPA method must
be presented in the complete data reporting package. If more than one method was used or
if more than one set of samples was analyzed, it must be clearly evident which QC
corresponds to a given method and set of samples.
Results for QC procedures that must be provided include, but are not limited to, the
following (where applicable):
Instrument tuning
Calibration
Calibration verification (initial and following every 10 analytical samples)
Initial precision and recovery
Ongoing precision and recovery
Blanks
Laboratory (method) blanks
Field blanks
Calibration blanks
Equipment blanks
Matrix spike/matrix spike duplicates
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Field duplicates
Method of standard additions (MSA) results
Spectral interference checks
Serial dilutions
Internal standard recoveries
Method detection limits
Quality control charts and limits
Table 2 lists the required frequency and purpose of the QC procedures.
5. Raw Data
Raw data for all analyses must be kept on file at the laboratory (Chapter 2, Section 7)
and submitted for inspection to the data reviewer upon request. The instrument output
(emission intensity, peak height, area, or other signal intensity) must be traceable from the
raw data to the final result reported. The raw data must be provided for not only the analysis
of each field sample but also for all calibrations, verifications, blanks, matrix spike/matrix
spike duplicates, field duplicates, and other QC analyses required by the reference method.
Raw data are method and instrument specific and may include, but are not limited to,
the following:
Sample numbers and other identifiers
Digestion/preparation or extraction dates
Analysis dates and times
Analysis sequence/run chronology
Sample weight or volume
Volume prior to each extraction/concentration step
Volume after each extraction/concentration step
Final volume prior to analysis
Injection volume
Matrix modifiers
Dilution data, differentiating between dilution of a sample or an extract
Instrument (make, model, revision, modifications)
Sample introduction system (ultrasonic nebulizer, hydride generator, flow injection
system, etc.)
Column (manufacturer, length, diameter, chelating or ion exchange resin, etc.)
Operating conditions (char/ashing temperatures, temperature program, incident rf
power, flow rates, plasma viewing height, etc.)
Detector (type, wavelength, slit, analytical mass monitored, etc.)
Background correction scheme
Quantitation reports, data system outputs, and other data to link the raw data to the
results reported
Direct instrument readouts (e.g., strip charts, mass spectra, printer tapes, and other
recordings of raw data) and other data to support the final results
Lab bench sheets and copies of all pertinent logbook pages for all field and QC
sample preparation and cleanup steps, and for all other parts of the determinations
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6. Example Calculations
Example calculations that will allow an independent reviewer to determine how the
laboratory used the raw data to arrive at a final result must be provided in the data reporting
package if any adjustments are made to the equations included in the methods. Useful
examples include both detected and undetected compounds. If the laboratory or the method
employs a standardized reporting level for undetected compounds, this should be made clear
in the example calculation. Adjustments made for sample volume, dilution, internal
standardization, etc. should be evident.
7. Archiving Data on Magnetic Media
It is not necessary for the laboratory or responsible organization to submit digitized
binary, hexadecimal, or other raw signal recordings with the data package. However, the
laboratory that performs the analysis should archive these data so that the raw reduced data
can be reconstructed, and the laboratory or organization responsible for reporting the data
should be prepared to submit raw data on magnetic media, upon request by EPA. Magnetic
media may be required for automated data review, for diagnosis of data reduction problems,
or for establishment of an analytical database.
8. Names, Titles, Addresses, and Telephone Numbers of Analysts and QC Officer
The names, titles, addresses, and telephone numbers of the analysts who performed
the determinations and the quality control officer who verified the results must be included
in the data reporting package. If the data package is being submitted by a person or
organization other than the analytical laboratory, it is that person or organization's
responsibility to ensure that the laboratory provides all the data listed above and that all
method requirements are met. For example, with regards to effluent or ambient monitoring
data submitted by an NPDES permittee on a Discharge Monitoring Report (DMR), the task
of collecting and reporting quality control data falls to the permittee.
In addition, the personnel, titles, addresses, telephone numbers, and name (if different
from the laboratory that analyzed the field samples) of the facility that cleaned and shipped
the sampling equipment and generated the equipment blanks, the laboratory (if different) that
analyzed the equipment blanks, and the facility responsible for the collection, filtration, and
transport of the field samples to the laboratory must be obtained and included in the data
reporting package.
Table 1
Method Numbers, Analytical Techniques, Method Detection Limits, and Minimum Levels
1 Method
Technique
Metal
MDL (ug/L)3
ML
Lowest EPA 1
Water Quality 1
Criterion (ug/L)5 |
Method Detection Limit as determined by 40 CFK Part 136, Appendix B
Minimum Level (ML) calculated by multiplying laboratory-determined MDL by 3.18 and rounding result to nearest multiple of 1, 2, 5, 10,
20,50 etc., in accordance with procedures utilized by BAD and described in the EPADraft National Guidance for the Permitting, Monitoring,
and Enforcement of Water Quality-Based Effluent Limitations Set Below Analytical Detection/Quantitation Levels, March 22, 1994.
Lowest of the freshwater, marine, or human health WQC at 40 CFR Part 131 (57 FR 60848 for human health criteria and 60 FR 22228 for
aquatic criteria). Hardness-dependent freshwater aquatic life criteria also calculated to reflect a hardness of 25 mg/L CaCO3, and all aquatic
life criteria, except chronic criteria for Hg and Se, have been adjusted to reflect dissolved levels in accordance with equations provided in 60
FR 22228. Hardness-dependent dissolved criteria conversion factors for Cd and Pb also calculated at ahardness of 25 mg/L per 60FR 22228.
A complete listing of all WQC, including total, dissolved, and levels calculated with a hardness of 25 mg/L CaCO3 is provided in Appendix
A.
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1631
1632
1636
1637
1638
1639
1640
Oxidation/Purge
& Trap/CVAFS
Hydride AA
Ion
Chromatography
CC/STGFAA
ICP/MS
STGFAA
CC/ICP/MS
Mercury
Arsenic
Hexavalent
Chromium
Cadmium
Lead
Antimony
Cadmium
Copper
Lead
Nickel
Selenium
Silver
Thallium
Zinc
Antimony
Cadmium
Trivalent
Chromium
Nickel
Selenium
Zinc
Cadmium
Copper
Lead
Nickel
0.0002
0.003
0.23
0.0075
0.036
0.0097
0.013
0.087
0.015
0.33
0.45
0.029
0.0079
0.14
1.9
0.023
0.10
0.65
0.83
0.14
0.0024
0.024
0.0081
0.029
0.0005
0.01
0.5
0.02
0.1
0.02
0.1
0.2
0.05
1
1
0.1
0.02
0.5
5
0.05
0.2
2
2
0.5
0.01
0.1
0.02
0.1
0.012
0.018
10
0.37
0.54
14
0.37
2.4
0.54
8.2
5
0.32
1.7
32
14
0.37
57
8.2
5
32
0.37
2.4
0.54
8.2
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Table 2 ~ Quality Control Requirements, Frequency, and Purpose
Required QC Test
Instrument tuning
Calibration (CAL)
Calibration verification (VKR)
Initial precision and recovery
(IPR)
Method detection limit (MDL)
and minimum level (ML)
Ongoing precision and recovery
(OPR)
Blanks
Matrix spike/matrix spike
duplicate (MS /MSB)
Field duplicate
Method of standard addition
(MSA)
Internal standardization
Spectral interference check
Serial dilutions
Frequency
Prior to calibration
Prior to sample analysis and whenever calibration cannot be verified
Immediately prior to and foil owing the analysis of every batch of 10 or fewer
analytical samples analyzed at the same time
Prior to using the method for the first time and each time a modification to the
method is made
Prior to using the method and whenever there is change that will affect the
MDL and ML
Each sample batch (Sample batch size is method specific. Where not specified,
batch size is 10.)
Equipment blankPrior to use of any sampling equipment at a given site
Calibration blank Immediately following each calibration verification
Laboratory (method) blank (BLK) One method blank per sample batch
Field blank (FBK) Every ten samples collected at a given site or at least one per
sample site, whichever is more frequent
Each batch of 10 or fewer samples from the same site
Each batch of 10 or fewer samples from the same site
As needed to assure the reliability of results for GFAA or ICP analyses
All analyses by ICP/MS (EPA Methods 200.8 and 200.10)
Prior to using the method for the first time and periodically thereafter as
indicated by instrument stability, type of samples analyzed, and expected
interferences encountered
When analyte concentration is sufficiently high (minimally a factor of 10X the
MDL after dilution)
Purpose
To assure that the instrument will produce results equivalent to instruments in
other laboratories
To establish the working range of the analytical instrument
To verify the average response or curve from the initial calibration
To establish the ability of the laboratory to generate acceptable precision and
recovery
To determine the lowest level at which the analyte can be detected with 99%
confidence that the concentration is greater than zero
To assure that the laboratory remains in control
To assure that contamination of sampling devices and apparatus for sample
collection will be detected prior to shipment to the field site
To assure that contamination of the analytical system will be detected, if present
To assure that contamination of the analytical process will be detected, if present
To assure that contamination of field samples will be detected, if present
To determine bias caused by sample matrix effects
To measure the precision associated with sample collection, preservation,
transportation, and storage procedures, as well as with analytical procedures
To compensate for a sample constituent that enhances or depresses the analyte
signal
To correct instrument drift and other variations in the analytical process
To establish corrections for known interelement spectral interferences
To determine if a chemical or physical interference effect is present
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Chapter 3
Guidance for Reviewing Data
from the Analysis of Trace Metals Using
Method 1669 and the 1600 Series Analysis Methods
Use of the guidelines provided below, or of similarly developed standardized
protocols, is highly recommended as a tool with which Regional and State permitting
authorities can standardize data inspection and acceptance procedures and minimize
differences that might otherwise result between data reviewers and/or permittees responsible
for submitting data. A Data Inspection Checklist has also been developed and is provided in the
following chapter. This checklist provides a standardized format for documenting the
findings of each data inspection and an additional tool for standardizing the data review
process within a regulatory agency.
1. Purity and Traceability of Reference Standards
The accuracy of any non-absolute empirical measurement is dependent on the
reference for that measurement. In determining pollutants in water or other sample matrices,
the analytical instrument and analytical process must be calibrated with a known reference
material of documented purity and traceability. This information need not be provided with
every sample analysis. Rather, it should be maintained on file at the laboratory and provided
upon request. When analyses are conducted in a contract laboratory, such documentation
should be provided to the permittee the first time that the laboratory is employed for specific
analyses and updated as needed.
2. Number of Calibration Points
The 1600 Series Analysis Methods specify that a minimum of three concentrations are
to be used when calibrating the instrument. One of these points must be the Minimum Level
(ML, see item 5), and another must be near the upper end of the calibration range.
Calibration must be performed for each target metal before any samples or blanks are
analyzed. The use of the ML as a point on the calibration curve is the principal means by
which to assure that measurements made at this quantitation level are reliable.
The data reviewer should review the points used by the laboratory to calibrate the
instrument and make certain that the calibration range encompasses the Minimum Level and
that all sample and QC measurements are within the calibration range. Samples that
produced results which exceeded the calibration range should have been diluted and
reanalyzed in accordance with the specifications detailed in the 1600 Series Analysis Method
that was used by the laboratory. The diluted sample results need only apply to those analytes
that exceeded the calibration range of the instrument. In other words, it is acceptable to use
data for different analytes from different levels within the same sample. Some flexibility may
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be exercised in acceptance of data that are only slightly above (<10%) the calibration range.
Such data are generally acceptable as calculated.
If data from an analysis of the diluted sample are not provided, limited use can be
made of the data that are above the calibration range (>10%). The response of the analytical
instrument to concentrations of analytes will eventually level off at concentrations above the
calibration range. While it is not possible to specify the concentration at which this will
occur, it is generally safe to assume that the reported concentration above the calibrated
range is a lower limit of the actual concentration. Therefore, if the concentration above the
calibration range is also above a regulatory limit, it is a virtual certainty that the actual
concentration would also be above that limit.
3. Linearity of Calibration
The relationship between the response of an analytical instrument to the
concentration or amount of an analyte introduced into the instrument is referred to as the
"calibration curve". An analytical instrument can be said to be calibrated in any instance in
which an instrumental response can be related to the concentration of an analyte. The
response factor (RF, calculated for external standard calibration) or relative response factor
(RRF, calculated for internal standard calibration) is the ratio of the response of the
instrument to the concentration of the analyte introduced into the instrument. Equations
for calculating RFs and RRFs are provided in the 1600 Series Analysis Methods.
While the shape of calibration curves can be modeled by quadratic equations or higher
order mathematical functions, most analytical methods focus on a calibration range in which
the linear calibration is essentially a function of the concentration of the analyte. The
advantage of the linear calibration is that the RF or RRF represents the slope of calibration
curve, simplifying calculations and data interpretation. The 1600 Series Analysis Methods
contain specific criteria for determining the linearity of calibration curves determined by
either an internal or external standard technique. When the applicable criterion is met, the
calibration curve is sufficiently linear to permit the laboratory to use an average RF or RRF,
and it is assumed that the calibration curve is a straight line that passes through the zero/zero
calibration point. Linearity is determined by calculating the relative standard deviation (RSD)
of the RF or RRF for each analyte and comparing this RSD to the specified limit. The
specific acceptance criteria are listed in the Data Inspection Checklist (Chapter 4, Item 12)
and in the 1600 Series Analysis Methods. These methods also include alternative procedures
to be used in the event the linearity criteria fail specifications.
The laboratory must provide the RSD results by which an independent reviewer can
judge linearity, even in instances in which the laboratory is using a calibration curve. In these
instances, the data reviewer should review each calibration point to assure that the response
increases as the concentration increases. If it does not, the instrument is not operating
properly, and the data should not be considered valid.
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4. Calibration Verification
Calibration verification involves the analysis of a single standard, typically in the
middle of the calibration range, at the beginning (and, in some cases, at the end) of each
analytical shift. The concentration of each analyte in a reference standard is determined
using the initial calibration data and compared to specifications in the method. If results are
within the specifications, the laboratory may proceed with analysis without recalibrating. The
initial calibration data are then used to quantify sample results. Specific criteria for
acceptance of calibration verifications are provided in the Data Inspection Checklist
(Chapter 4, Item 17) and the 1600 Series Analysis Methods.
Calibration verification, which is used in the 1600 Series Analysis Methods, differs in
concept and practice from "continuing calibration", which is used in the SW-846 methods
and in the Superfund Contract Laboratory Program (CLP). In continuing calibration, a
standard is analyzed and new response factors are calculated on the basis of that analysis.
If the new factors are close to the average from the initial calibration, all subsequent sample
analyses are conducted using the new response factors. The degree of "closeness" is
generally measured as the percent difference between the old and new factors. The problem
with continuing calibration is that it amounts to a daily single-point calibration. Information
about the behavior of the instrument at concentrations above and below this single standard
can only be inferred from the initial multiple-point calibration.
The 1600 Series Analysis Methods require calibration verification after every ten
samples. Calibration verification is performed by analyzing an aliquot of the mid-point
calibration standard, and obtaining results that meet the specifications contained in the
methods. These specifications are given for each method and metal as a percentage of the
recovery of the mid-point calibration standard. If any individual value falls outside the range
given, system performance is considered unacceptable, and the laboratory may either
recalibrate the instrument or prepare a new calibration standard and make a second attempt
to verify calibration. The data reviewer should verify that each batch of 10 samples is
associated with a calibration verification that meets the required performance criteria.
5. Method Detection Limit and Minimum Level
The Minimum Level (ML) is defined in the 1600 Series Analysis Methods as the
lowest level at which the entire analytical system gives a recognizable signal and acceptable
calibration point. Therefore, each 1600 Series Analysis Method requires that the calibration
line or curve for each analyte encompass the method-specified ML.
The 1600 Series Analysis Methods also require each laboratory to perform a method
detection limit (MDL) study for each analyte in accordance with the procedures given in 40
CFR Part 136, Appendix B. The MDL studies are conducted to demonstrate that the
laboratory can achieve the MDLs listed in the methods. MDL determinations must be made
the first time that the laboratory utilizes the method and each time the laboratory utilizes a
new instrument or modifies the method in any way.
Each MDL and ML listed in the 1600 Series Analysis Methods represents the results
of MDL studies conducted by the EPA's Engineering and Analysis Division as part of its
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effort to validate the methods. The MDL studies were conducted by at least one laboratory
for each method and metal in accordance with the procedure given in 40 CFR Part 136,
Appendix B. The MLs shown in Table 1 were calculated by multiplying each laboratory-
determined MDL by 3.18 and rounding the result to the nearest multiple of 1, 2, 5, 10, 20,
50, etc. in accordance with the procedures described in the EPA Draft National Guidance for the
Permitting, Monitoring, and Enforcement of Water Quality-Eased Effluent Limitations Set Below Analytical
Detection/Quantitation Levels, March 22, 1994.
The 1600 Series Analysis Methods and Chapter 2 of this document require the
laboratory to report the concentration of all sample results that are at or above the ML. It
should be noted that this ML is a sample-specific ML and, therefore, reflects any sample
dilutions that were performed. If sample results are reported below the ML, the data
reviewer should require the responsible party to correct and resubmit the data, or if this
course of action is not possible, the reviewer should determine the sample-specific ML and
consider results below that level to be non-detects for regulatory purposes.
If sample results are reported above the ML, but are below the facility's regulatory
compliance level, then the data reviewer should consider the results to suggest that the
pollutant has been detected but is compliant with the facility's permit (assuming that all QC
criteria are met). If sample results are reported above the regulatory compliance level, the
data reviewer must evaluate laboratory QC samples in order to verify that the level of
pollutant is not attributable to analytical bias. In addition, the data reviewer must evaluate
all blank sample results in order to determine if the level of pollutant detected may be
attributable to contamination.
Although sample results are to be reported only if they exceed the ML, all blank
results are to be reported, regardless of the level. This reporting requirement allows data
reviewers the opportunity to assess the impact of any blank contamination on sample results
that are reported above the ML.
It is important to remember that if a change that will affect the MDL is made to a
method, the MDL procedure must be repeated using the modified procedure. Changes may
include alternate digestion, concentration, and cleanup procedures, and changes in
instrumentation. Alternate determinative techniques, such as the substitution of a
colorimetric technique or changes that degrade method performance are not allowed. The
data reviewer should verify that method modifications were appropriate and were capable
of producing the desired MDLs.
The procedures given in this document are for evaluation of results for determination
of regulatory compliance, and not for assessment of trends, for triggering, or for other
purposes. For such other purposes, the reporting of all results, whether negative, zero,
below the MDL, above the MDL but below the ML, or above the ML, may be of value and
may be required by the permitting authority as necessary to enforce in a particular
circumstance. Dealing with the multiplicity of consequences presented by such results, either
singly or in combination, is beyond the present scope of this document.
6. Initial Precision and Recovery
12 Draft, July 1996
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The laboratory is required to demonstrate its ability to generate acceptable precision
and accuracy data using the techniques specified in the 1600 Series Analysis Methods. This
test, which is sometimes termed the "start-up test", must be performed by the laboratory
prior to the analysis of field samples with the specified methods and prior to the use of
modified versions of the methods on field samples. EPA's experience has been that
laboratories that have difficulty passing the start-up test have such marginal performance that
they will have difficulty in the routine practice of the method.
The test consists of spiking four aliquots of reagent water with the metals of interest
at 2 - 3 times the ML concentrations listed in the methods and analyzing these four aliquots.
The mean concentration (x) and the standard deviation (s) are then calculated for each
analyte and compared to the specifications in the methods. If the mean and the standard
deviation are within the limits, the laboratory can use the method to analyze field samples.
If the start-up test data fail to meet the specifications in the method, none of the data
produced by the laboratory can be considered to be valid. If the laboratory did not perform
the start-up tests, the data cannot be valid, unless all other QC criteria have been met and the
laboratory has submitted IPR (and associated instrument QC) data that were generated after-
the-fact by the same analyst on the same instrument. If these conditions are met, then the
data reviewer may consider the data to be acceptable for most purposes. NOTE: The
inclusion of this alternative should not in any way be construed to sanction the practice of
performing IPR analyses after the analysis of field samples. Rather, EPA believes that
demonstration of laboratory capability prior to sample analysis is an essential QC
component; this alternative is provided only as a tool to permitting authorities when data
have already been collected without the required IPR samples. Once the problem has been
identified, all responsible parties are expected to implement corrective action necessary to
ensure that it is not repeated.
It is important to remember that if a change is made to a method, the IPR procedure
must be repeated using the modified procedure. If the start-up test is not repeated when
these steps are modified or added, any data produced by the modified methods cannot be
considered to be valid.
7. Analysis of Blanks
Because trace metals are ubiquitous in the environment, the precautions necessary to
preclude contamination are more extensive than those required to preclude contamination
when synthetic organic compounds and other non-ubiquitous substances are determined.
EPA has found that the greatest potential for contamination of samples analyzed for trace
metals has been from atmospheric input in the field and laboratory and from inadequate
cleaning of sample bottles and labware. In order to prove that such contamination is
avoided during sampling, sample transit, and analysis, Method 1669 and the 1600 Series
Analysis Methods specify the collection and analysis of numerous blank samples. These
include:
Equipment blanks that are collected prior to the use of any sampling equipment at a
given site and provide a means for detecting contamination of sampling devices and
apparatus prior to shipment to the field site,
Draft, July 1996 13
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Field blanks that are collected for each batch of 10 or fewer samples from the same
site and provide a means of detecting contamination that arises in the field,
Calibration blanks that are analyzed immediately after each calibration verification
and provide a means of detecting contamination that arises from the analytical system,
and
Laboratory (method) blanks that are analyzed for each batch of samples analyzed on
a particular instrument and provide a means of detecting contamination from the
analytical process.
While the analysis of a minimum of four blank samples per site may seem to be
excessive, particularly when very few (e.g., < 5) samples are collected, EPA has found that
the validity of entire studies may be suspect when pollutants are identified in samples that are
not associated with each of these blanks. In general, it is not necessary for a facility to report
the results of equipment blank analyses unless contamination is identified in field blanks.
Therefore, the permittee should obtain equipment blank results from its cleaning facility,
maintain these results on file, and provide them to the permitting authority upon request.
The data reviewer should evaluate equipment blank results only if it is necessary to identify
potential sources of contamination present in field blanks.
Controlling laboratory contamination is an important aspect of the quality assurance
plan for the equipment-cleaning facility, laboratory, and field team. Each party should
maintain records regarding blank contamination. Typically, these records take the form of
a paper trail for each piece of equipment and control charts, and they should be used to
prompt corrective action by the party associated with the contamination. For example, if
records at a single site suggest that equipment blanks, laboratory blanks, and calibration
blanks are consistently clean but that field blanks show consistent levels of contamination,
then the field sampling team should re-evaluate their sample handling procedures, identify
the problem, and institute corrective actions before collecting additional samples. Similarly,
equipment cleaning facilities and laboratories should utilize the results of blank analyses to
identify and correct problems in their processes.
Unfortunately, it is often too late for corrective action if data are received that suggest
the presence of uncontrolled contamination that adversely affects the associated data. The
exception to this rule is the case in which the field and equipment blanks show no
discernable levels of contamination, contamination is detected in the laboratory or
calibration blanks, sample holding times have not expired, and sufficient sample volume
remains to allow the laboratory to identify and eliminate the source of contamination and
reanalyze the associated sample(s). In all other cases, the reviewer must exercise one of
several options listed below when making use of the data.
14 Draft, July 1996
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If a contaminant is present in a blank but is not present in a sample, then there is little
need for concern about the sample result. (It may be useful, however, to occasionally
review the raw data for samples without the contaminant to ensure that the laboratory
did not edit the results for this compound.)
If the sample contains the contaminant at levels of at least 10 times that in the blank,
then the likely contribution to the sample from the contaminant in the sample is at
most 10%. Since most of the methods in question are no more accurate than that
level, the possible contamination is negligible, and the data can be considered to be
of acceptable quality.
If the sample contains the contaminant at levels of at least 5 times but less than 10
times the blank result, the numerical result in the sample should be considered an
upper limit of the true concentration, and data users should be cautioned when using
such data for enforcement purposes.
If the sample contains the contaminant at levels below 5 times the level in the blank,
the sample data are suspect unless there are sufficient data from analyses of multiple
blanks to perform a statistical analysis proving the significance of the analytical result.
Such statistical analyses are beyond the scope of this guidance.
If blank contamination is found in some types of QC samples but not others (e.g.,
only in the laboratory blank but not in the field blank), the data user should apply the
guidelines listed above, but may also use this information to identify the source of
contamination and take corrective actions to prevent future recurrences.
There are two difficulties in evaluating sample results relative to blank contamination.
First, the reviewer must be able to associate the samples with the correct blanks. Field blanks
are associated with each group of field samples collected from the same site. Calibration
blanks are associated with samples by the date and time of analysis on a specific instrument.
Laboratory (method) blanks are associated with each batch of 10 samples prepared and
digested in accordance with a particular method during a single shift. If the reviewer cannot
associate a batch of samples with a given blank, the reviewer should request this association
from the laboratory so that the results for the samples can be validated.
The second difficulty involves samples that have been diluted. The dilution of the
sample with reagent water represents an additional potential source of contamination that
will not be reflected in the results for the blank unless the blank was similarly diluted.
Therefore, in applying the 10-times rule stated above, the concentration of the sample is
compared to the blank results multiplied by the dilution factor of the sample. For instance,
if 1.2 ppb of a contaminant is found in the blank, and the associated sample was diluted by
a factor of six relative to the extract from the blank prior to analysis, then the diluted sample
result would have to be greater than 1.2 x 6 x 10 or 72 ppb to be acceptable. Diluted sample
results between 36 and 72 ppb would be considered an upper limit of the actual
concentration, and diluted sample results that were less than 36 ppb would be considered
unacceptable in the absence of sufficient blank data to statistically prove the significance of
the result.
Draft, July 1996 15
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In most cases, the practice of subtracting the concentration reported in the blank
from the concentration in the sample is not recommended as a tool to evaluate sample
results associated with blank data. One of the most common problems with this approach
is that blank concentrations are sometimes higher than one or more associated sample
results, yielding negative results.
Nearly all of the 1600 Series Analysis Methods are capable of producing MDLs that
are at least 10 times lower than the lowest water quality criteria (WQC) published in the
National Toxics Rule. Since most discharge permits require monitoring at levels that are
comparable to or higher than the WQC published in the National Toxics Rule, EPA believes
that, in nearly all cases, laboratories should be capable of producing blank data that are at
least 10 times less than the regulatory compliance level. It should also be noted that
laboratories cannot be held accountable for contamination that is present in field blanks but
not present in laboratory blanks; in such cases the sampling crew should take corrective
measures to eliminate the source of contamination during their sample collection and
handling steps.
8. Ongoing Precision and Recovery
The 1600 Series Analysis Methods require laboratories to prepare and analyze an
"ongoing precision and recovery" (OPR) sample with each batch of up to 10 samples started
through the extraction process on the same twelve hour shift. This OPR sample is identical
to the aliquots used in the IPR analyses (see Item 6), and the results of the OPR are used to
ensure that laboratory performance is in control during the analysis of the associated batch
of field samples.
The data reviewer must verify that the OPR sample has been run with each sample
batch and that the applicable recovery criteria in the analytical method have been met. If the
recovery criteria have not been met, the reviewer may use the following guidelines when
making use of the data:
If the concentration of the OPR is above method specifications but that analyte is not
detected in an associated sample, then it unlikely that the sample result is affected by
the failure in the OPR.
If the concentration of the OPR is above method specifications and that analyte is
detected in the sample, then the numerical sample result may represent an upper limit
of the true concentration, and data users should be cautioned when using the data for
enforcement purposes.
If the concentration of the OPR is below method specification but that analyte is
detected in an associated sample, then the sample result may represent the lower limit
of the true concentration for that analyte.
If the concentration of the OPR is below method specification and that analyte is not
detected in an associated sample, then the sample data are suspect and cannot be
considered valid for regulatory compliance purposes.
16 Draft, July 1996
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If the OPR standard has not been run, there is no way to verify that the laboratory
processes were in control. In such cases, a data reviewer may be able to utilize the field
sample data by examining the matrix spike recovery results (see item 9), the IPR results, OPR
results from previous and subsequent batches, and any available historical data from both
the laboratory and the sample site. If the matrix spike results associated with the sample
batch do not meet the performance criteria in the methods, then the results for that set of
samples cannot be considered valid. If the laboratory's IPR results and the matrix spike
results associated with the sample batch in question meet the all applicable performance
criteria in the methods, then the data reviewer may be reasonably confident that laboratory
performance was in control during field sample analysis. This level of confidence may be
further increased if there is a strong history of both laboratory performance with the method
and method performance with the sample matrix in question, as indicated by additional OPR
and matrix spike data collected from the laboratory and samples from the same site.
9. Precision and Recovery of Matrix Spike and Matrix Spike Duplicate Compounds
The 1600 Series Analysis Methods require that laboratories spike the analytes of
interest into duplicate aliquots of at least one sample from each group of ten samples
collected from a single site. The first of these spiked sample aliquots is known as the matrix
spike sample; the second is known as the matrix spike duplicate. These spiked sample
aliquots are used to determine if the method is applicable to the sample matrix in question.
The 1600 Series Analysis Methods are applicable to the determination of metals at
concentrations typically found in ambient water samples and certain treated effluents (e.g.,
the part-per-trillion to low part-per-billion range). These methods may not be applicable to
marine samples and many effluent and in-process samples collected from industrial
dischargers. Therefore, it is important to evaluate method performance in the sample matrix
of interest.
In evaluating matrix spike sample results, it is important to examine both the precision
and accuracy of the duplicate analyses. Precision is assessed by examining the relative percent
difference (RPD) of the concentrations found in the matrix spike and matrix spike duplicate
samples, and comparing the RPD to the acceptance criteria specified in the analytical
method. If the RPD of a matrix spike/matrix spike duplicate pair exceeds the applicable
criterion, then the method cannot be considered to be applicable to the sample matrix, and
none of the associated sample data can be accepted for regulatory compliance purposes.
If RPD criteria are met, the method is considered to be capable of producing precise
data in these samples, and the data reviewer must then verify that the method is capable of
producing accurate data. Accuracy is assessed by examining the recovery of compounds in
the matrix spike and matrix spike duplicate samples. If the recovery of the matrix spike and
duplicate are within the method-specified limits, then the method is judged to be applicable
to that sample matrix. If, however, the recovery of the spike is not within the recovery range
specified, either the method does not work on the sample, or the sample preparation process
is out of control.
If the method is not appropriate for the sample matrix, then changes to the method
are required. Matrix spike results are necessary in evaluating the modified method. If the
Draft, July 1996 17
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analytical process is out of control, the laboratory must take immediate corrective action
before any more samples are analyzed.
To separate indications of method performance from those of laboratory
performance, the laboratory should prepare and analyze calibration verification standards
and OPR samples. If the results for either of these analyses are not within the specified
range, then the analytical system or process must be corrected. After the performance of the
analytical system and processes have been verified (through the successful analysis of CCV
and OPR samples), the spike sample analysis should be repeated. If the recovery of the
matrix spike and duplicate are within the method-specified range, then the method and
laboratory performance can be considered acceptable. If, however, the recovery of the
matrix spike does not meet the specified range, the laboratory should attempt to further
isolate the metal and repeat the test. If recovery of the metal remains outside the acceptance
criteria, the data reviewer may apply the following guidelines when attempting to make use
of the data:
If the recovery of the matrix spike and duplicate are above method specifications but
that metal is not detected in an associated sample or is detected below the regulatory
compliance limit, then it unlikely that the sample result is affected by the failure in the
matrix spike.
If the recovery of the matrix spike and duplicate are above method specifications and
that metal is detected in an associated sample above the regulatory compliance level,
then the sample result may represent the upper limit of the true concentration, and
the data should not be considered valid for regulatory compliance purposes.
If the concentration of the matrix spike and duplicate are below method
specifications but that metal is detected in an associated sample, then the sample result
may represent the lower limit of the true concentration for that metal. If the metal
was detected in the sample at a concentration higher than the regulatory compliance
limit, then it is unlikely that the sample result is adversely affected by the matrix. If,
however, the metal was detected below the regulatory compliance limit, the data
should not be considered valid for regulatory compliance purposes.
10. Statements of Data Quality for Spiked Sample Results
The 1600 Series Analysis Methods specify that after the analysis of five spiked samples
of a given matrix type, a statement of data quality is constructed for each analyte. The
statement of data quality for each analyte is computed as the mean percent recovery plus and
minus two times the standard deviation of the percent recovery for the analyte. The
statements of data quality should then be updated by the laboratory after each five to ten
subsequent spiked sample analysis.
The statement of data quality can be used to estimate the true value of a reported
result and to construct confidence bounds around the result. For example, if the result
reported for analysis of selenium is 10 ppb, and the statement of data quality for selenium
is 84% ± 25% (i.e., the mean recovery is 84% and the standard deviation of the recovery is
18 Draft, July 1996
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25%), then the true value for selenium will be in the range of 9.4 - 14.4 ppb, with 95%
confidence. This range is derived as follows:
Lower Limit = [(10 - .84) - (10 x .25)] = [11.9 - 2.5] = 9.4 ppb
Upper Limit = [(10 - .84) + (10 x .25)] = [11.9 + 2.5] = 14.4 ppb
Many laboratories do not provide the data quality statements with the sample results,
in which case the data reviewer must determine if the data quality statements are being
maintained for each analyte and may need to obtain the data. If necessary, the reviewer can
construct the data quality statement from the individual data points. The lack of a data
quality statement does not invalidate results but makes some compliance decisions more
difficult. If statements of data quality are not being maintained by the laboratory, there may
be increased concern about both specific sample results and the laboratory's overall quality
assurance program.
11. Statements of Data Quality for Spiked Reagent Water Results
In addition to statements of data quality for results of analyses of the compounds
spiked into field samples, the 1600 Series Analysis Methods require that statements of data
quality be constructed from the initial and ongoing precision and recovery data. The purpose
of these statements is to assess laboratory performance in the practice of the method, as
compared to the assessment of method performance made from the results of spiked field
samples. Ideally, the two statements of data quality would be the same. Any difference could
be attributable to either random error or sample matrix effects.
12. Field Duplicates
Method 1669 requires the collection of at least one field duplicate for each batch of
field samples collected from the same site. The field duplicate provides an indication of the
overall precision associated with entire data gathering effort, including sample collection,
preservation, transportation, storage, and analysis procedures. The data reviewer should
examine field duplicate results and use the following equation to calculate the relative percent
difference between the duplicate and its associated samples.
RPD - 2
(D1+D2)
where:
Dl = concentration of the analyte in the field sample
D2 = concentration of the analyte in the duplicate field sample
If the analyte of interest was not detected in either replicate of the field sample, then
the RPD will be zero. If the analyte was detected in each field sample replicate, but the
results are highly disparate (indicated by a large RSD), the reviewer should apply the
following guidelines when making use of the data:
Draft, July 1996 19
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If the analyte was detected in each replicate and at similarly variable concentrations
in the blank samples, then the field sample variability may be attributable to variable
contamination, and the data may not be valid for regulatory compliance purposes.
If the analyte was detected in each replicate at a concentration well above the
regulatory compliance level, but was not detected in the associated blank samples,
then it is likely that the sample results are not adversely affected.
Ideally, the RPD between field duplicates and MS/MSD samples will be identical.
Any difference between the two is attributable to variability associated with the field sampling
process.
20 Draft, July 1996
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Chapter 4
Data Inspection Checklist
The following pages contain a data inspection checklist that may be used by data
reviewers, laboratory personnel, and other parties to document the results of each data
inspection in a standardized format.
Draft, July 1996 21
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Data Inspection Checklist
Summary Information
1. Name of Reviewer:
Tide:
Required Samples
Sample Results Provided
Sample Location or
Sample ID
Analyte(s)
Sample Location or
Sample ID
Analyte(s)
2. Metiiod Used:
3. Total No. of analytical shifts per instrument (determined from analysis run 1
Instrument
4. Total No. of CCVs Required:
(one for each 10 samples after the
first 10 samples on each instrument)
5. Total No. of CCBs Required:
(one for each CCV)
6. Total No. of Field Blanks Required:
(one per site or per 10 samples, whichever
is more frequent)
7. Total no. of Lab Blanks Required:
(one per batch* per method/instrument)
8. Total no. of OPR analyses Required:
(one per batch per method/instrument)
9. Total no. of MS/MSD samples Required:
(one per 10% per matrix per site)
10. Total no. Field Duplicates Required:
(one per 10 samples per site)
11. Total no. of MDL results required:
(one per method and per analyte)
No. of Shifts
Total No. of CCVs Reported:
Total No. of CCBs Reported:
Total No. of Field Blanks Reported:
Total No. of Lab Blanks Reported:
Total No. of OPR Analyses Reported:
Total No. of MS/MSD samples Reported:
Total No. of Field Duplicates Reported:
Total No. of MDL Results Reported:
22
Draft, July 1996
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12. Initial Calibration
a. Was a multiple point initial calibration performed*? Gyes Gno
b. Were all sample concentrations reported within the calibration range? Gyes
If no, list method and analytes for which initial calibration was not performed or which exceeded the
calibration range.
c. Analyte No ICAL (Y/N) Exceeded ICAL Range (Y/N)
d. Did the initial calibration meet linearity criteria? Gyes Gno
e. If no, was a calculation curve used to calculate sample concentrations? Gyes Gno
* A three point (minimum) initial calibration should be performed for each analyte; if the RSD of the mean RRF is less than 15%, or if the RSD of the mean RF i
less than 25%, then the averaged RRF or RF, respectively, may be used for that analyte.
13. Method Detection Limit (MDL)/Minimum Level (ML)
a. Did the laboratory demonstrate their ability to achieve the required MDL? Gyes Gno
b. Did the initial calibration range encompass the ML? Gyes
c. Were all field samples detected below the ML reported as non-detects? Gyes Gno
d. If the answer to item a, b, or c above was "no", describe problem:
14. Initial Calibration Verification (ICV)/Initial Calibration Blanks (ICB):
a. Was an ICV run prior to field samples? Gyes Gno
b. Were ICV results within the specified windows? Gyes Gno
c. Was the ICV followed by an ICB? Gyes
d. Was the ICB free from contamination? Gyes Gno
e. If any item in a - d above was answered "no", list problems below:
Analyte Failed ICV Recovery Concentration Detected in ICB Affected Samples
Draft, July 1996 23
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15. Initial Precision and Recovery (IPR)
a. Were IPR data reported for each analyte? Gyes Gno
b. Did all IPR aliquots meet required recovery criteria (x)? Gyes Gno
c. Did the standard deviation (s) of each IPR series meet the required criterion? Gyes Gno
d. If any item in a - c above was answered "no", document problem below.
Analyte Aye. Result Reported (X) RSD Reported Affected Samples
16. Ongoing Precision and Recovery (OPR)
a. Were OPR data reported for each analyte, instrument, and batch? Gyes Gno
b. Did all OPR samples meet required recovery criteria (x)? Gyes Gno
c. If item a or b above was answered "no", document problem below.
Analyte OPR Recovery (X) Reported Shifts Missing OPR Affected Samples
17. Continuing Calibration Verification (CCV)/Continuing Calibration Blank (CCB)
a. Were CCVs run prior to each batch of 10 samples on each instrument? Gyes Gno
b. Were all CCV results within the specified windows? Gyes Gno
c. Was each CCV followed by a CCB? Gyes Gno
d. Was each CCB free from contamination? Gyes Gno
e. If any item in a - d above was answered "no", list problems below:
Analyte Affected Samples Shift Missing CCV/CCB Failed CCV/CCB ID
24 Draft, July 1996
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18.
a.
b.
c.
19.
a.
b.
c.
20.
a.
b.
c.
d.
e.
Laboratory (Method) Blanks
Was a method blank analyzed for each instrument & sample batch? Gyes Gno
Was each method blank demonstrated to be free from contamination? Gyes Gno
If the answer to item a or b was "no", document problems below.
Analvte Affected Samples
Was a field blank analyzed for each
Was each field blank demonstrated
Blank Concentration Reported Shift Missing MB
Field Blanks
10 samples per site? Gyes Gno
to be free from contamination? Gyes Gno
If the answer to item a or b was "no", document problems below.
Analvte Affected Samples
Blank Concentration Reported Shift Missing FB
MS/MSD Results
Were appropriate number of MS/MSD pairs analyzed? Gyes Gno
Were all MS/MSD recoveries within specified windows? Gyes Gno
Were all RPDs within the specified
window? Gyes Gno
Was appropriate corrective action (e.g., MSA for GFAA, serial dilution
for ICP) employed on affected samples? Gyes Gno
If the answer was "no" to items a -
d above, document affected samples:
Analvte MS % R MSD % R MS/MSD RPD Affected Samples
21.
a.
b.
c.
d.
Additional Information
Were Instrument Tune Data Provided? Gyes Gno
Were equipment blanks demonstrated to be free from contamination? Gyes Gno
Were statements of data quality provided? Gyes Gno
Did field duplicate demonstrate acceptable precision? Gyes Gno
Draft, July 1996 25
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Glossary
Accuracy: The degree of agreement between a measured value and the true or expected value
of the quantity of concern.
Calibration Blank: A sample of reagent water analyzed after the calibration verification
standard to check for contamination attributable to the analytical system.
Calibration Range (Calibration Curve): A graphical relationship between the known values for
a series of calibration standards and instrument responses, specifically the linear portion of
this relationship between calibration standards.
Dissolved Metals: The concentration of metal(s) that will pass through a 0.45 micron filter
assembly, prior to acidification of the sample.
Equipment Blank: An aliquot of reagent water that is subjected in the laboratory to all aspects
of sample collection and analysis, including contact with all sampling devices and apparatus.
The purpose of the equipment blank is to determine if the sampling devices and apparatus
for sample collection have been adequately cleaned prior to shipment to the field site. An
acceptable equipment blank must be achieved before the sampling devices and apparatus are
used for sample collection.
Field Blank: An aliquot of reagent water that is placed in a sample container in the laboratory,
shipped to the sampling site, and treated as a sample in all respects, including contact with
the sampling devices and exposure to sampling site conditions, storage, preservation, and all
analytical procedures, which may include filtration. The field blank is used to determine if
field sample handling processes, sample transport, and sampling site environment have
caused sample contamination.
Field Duplicates: Two identical aliquots of a sample collected in separate sample containers
at the same time and place under identical circumstances and sample collection techniques,
and handled in exactly the same manner as other samples. Field duplicates are used as a
measure of the precision associated with sample handling, preservation, and storage as well
as laboratory handling, preparation, and analytical procedures.
Initial Precision and Recovery (IPR): A series of four consecutively analyzed aliquots of reagent
water containing the analyte(s) of interest at 2 - 3 times the ML. IPRs are performed prior
to the first time a method is used and any time the method or instrumentation is modified.
The IPR is used to demonstrate the analyst/laboratory ability to generate acceptable
precision and accuracy through the calculated mean (x) and standard deviation (s) for each
analyte.
Laboratory Blank: An aliquot of reagent water that is treated exactly as a sample including
exposure to all glassware, equipment, solvents, reagents, internal standards, and surrogates
that are used with samples. the laboratory blank is used to determine if analytes or
interferences are present in the laboratory environment, reagents, or the apparatus.
26 Draft, July 1996
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Magnetic Media: A storage medium on which all instrumentally acquired raw data may be
retained.
Matrix Spike (MS) and Matrix Spike Duplicate (MSD): Aliquots of an environmental sample to
which known quantities of analytes are added in the laboratory. The MS and MSD are
analyzed under the same conditions as other samples and are used to quantify the bias and
precision associated with the sample matrix. The background concentration of the analytes
in the sample are determined and subtracted from the MS and MSD results.
Method Blank: See "laboratory blank".
Method Detection Limit (MDL): The minimum concentration of an analyte that, in a given
matrix and with a specified method, has a 99% probability of being identified, qualitatively
or quantitatively measured, and reported to be greater than zero.
Minimum Level (ML): The lowest level at which the entire analytical system gives a
recognizable signal and acceptable calibration point.
Ongoing Precision and Recovery (OPR): An aliquot of reagent water containing the analyte(s)
of interest. The OPR is used to demonstrate continuing ability of the analyst/laboratory to
generate acceptable results based on target and standard recoveries.
Quality Assurance (QA): An integrated system of activities involving planning, quality control,
quality assessment, reporting, and quality improvement to ensure that a product or service
meets defined standards of quality with a stated level of confidence.
Quality Control (QC): The overall system of technical activities designed measure and control
the quality of a product or service so that it meets the needs of users. The aim is to provide
quality that is satisfactory, adequate, dependable, and economical.
Precision: The degree of mutual agreement characteristic of independent measurements as
the result of repeated applications of the process under specified conditions.
Reagent Water: Water demonstrated to be free from the metal(s) of interest at the method
detection limit (MDL) of the analytical method to be used for determination of the metal(s)
of interest.
Reference Standards: A material or substance, one or more properties of which are sufficiently
well established to be used for the calibration of analytical apparatus, the assessment of a
measurement method, or assigning of values to materials.
Trace Metals: Concentrations of metals found at or near their established water quality
criteria levels.
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Appendix A
EPA Water Quality Criteria for
Priority Pollutant Metals and Metals Species
The table provided on the following page provides the freshwater, marine, and human health
water quality criteria published by EPA for priority pollutant metals and metals species.
Human health criteria reflect values published by EPA in the National Toxics Rule at 57 PR
60848. Aquatic criteria reflect values published by EPA in the National Toxics Rule and in
the Stay of Federal Water Quality Criteria for Metals (60 PR 22228). This table includes
criteria for both total recoverable metals and dissolved metals. In addition, the table includes
freshwater criteria that are based on a hardness of 100 mg/L. In order to provide a worst-
case scenario, the table also includes criteria that are based on a hardness of 25 mg/L CaCO3.
Calculations for deriving these values were published by EPA at 60 PR 22228.
28 Draft, July 1996
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EPA Ambient Water Quality Criteria for Total Recoverable and Total Dissolved Priority Pollutant Metals and Metal Species
Calculated at a Hardness of 100 mg/L and 25 mg/L CaCO3
Metal
Sb
As
Cd'6'
Cr (III)'6'
Cr (VI)
Cu'''
pbW
Hg
Ni<6'
Se
Ag<"
TI
Zn<6'
Ambient Water Quality Criteria'1' (re/L)
Freshwater Criteria
Acute'2'
Tot. Rec.
100 mg/L
CaCOj
360
3.9
1700
16
18
82
2.4
1400
20
4.1
120
Acute'3'
Tot. Diss.
100 mg/L
CaCO3
360
3.7
550
15
17
65
2.1
1400
___P)
3.4
110
Acute<4>
Tot. Rec.
25 mg/L
CaCOj
360
0.82
560
16
4.8
14
2.4
440
20
0.37
36
Acute'3"4'
Tot. Diss.
25 mg/L
CaCO3
360
0.82
180
15
4.6
14
2.1
440
___P)
0.32
35
Chrome'2'
Tot. Rec.
100 mg/L
CaCOj
190
1.1
210
11
12
3.2
0.012
160
5.0
110
Chrome'3'
Tot. Diss.
100 mg/L
CaCO3
190
1.00
180
10
11
2.5
(?)
160
___P)
100
Chronic'4'
Tot. Rec.
25 mg/L
CaCOj
190
0.38
67
11
3.6
0.54
0.012
49
5.0
33
Chronic'3'-'4'
Tot. Diss.
25 mg/L
CaCOj
190
0.37
57
10
3.5
0.54
(?)
49
___P)
32
Marine Criteria
Acute'2'
Tot. Rec.
69
43
1100
2.9
220
2.1
75
290
2.3
95
Acute'3'
Tot. Diss.
69
42
1100
2.4
210
1.8
74
290
2.0
90
Chronic'2'
Tot. Rec.
36
9.3
50
2.9
8.5
0.025
8.3
71
86
Chronic'3'
Tot. Diss.
36
9.3
50
2.4
8.1
(7)
8.2
71
81
Human Health Criteria
H2O /organism'2'
Tot. Rec.
ws>
O.OttP>
0.14
610'5'
1.W
organism'3'
Tot. Rec.
4300'5'
0.14'5'
0.15
4600'5'
6.3'5'
WQC promulgated at 40 CFR Part 131 (57 FR 60848 and 60 FR 22228). Cntna for metals listed at 40 CFR Part 131 are expressed as total recoverable at a hardness of 100 mg/L CaCO3 and a water effect ratio (WER) of
1.0. The lowest WQC for each analyte is shaded.
As listed in the NTR at 40 CFR Part 131 for total recoverable metals. Hardness dependent freshwater acute and chronic criteria expressed at a hardness of 100 mg/L CaCO3 and a WER of 1.0.
For As, Cd, Cr(III), Cr(VI), Cu, Ni, Pb, and Zn, acute and chronic criteria for dissolved metals and metal species were calculated in accordance with the equations provided at 60 FR 22228. Hardness-dependent dissolved
criteria conversion factors for Cd and Pb also cacluated at a hardness of 25 mg/L per 60 FR 22228.
Hardness dependent freshwater acute and chronic criteria recalculated at a hardness of 25 mg/L CaCO3 and a WER of 1.0 as specified at 40 CFR Part 131.36 (b)(2). For dissolved metals, hardness calculations were performed
prior to adjusting for dissolved levels.
Criterion reflects recalculated value using IRIS.
Freshwater criteria are hardness dependent for this metal.
Metal is bio accumulative and, therefore, it is not appropriate to calculate WQC for dissolved levels. (Guidance Document on Dissolved Criteria: Expression oJA.quatic Life Criteria, October 1993. Attachment 2 to memorandum
from Martha Pro thro to Water Management Division Directors, October 1, 1993.)
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