EFtt
United States
Environmental Protection
Agency
Protocol for the Evaluation of Alternate Test Procedures
for Organic and Inorganic Analytes in Drinking Water
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Off ice of Water (MS-140)
EPA815-R-15-007
February 2015
Questions concerning this document should be addressed to:
Steyen_C.JA/ende|kenJ_PhD
U.S. EPA, Office of Ground Water and Drinking Water, Standards and Risk Management Division-
Technical Support Center, 26 W. Martin Luther King Dr. Cincinnati, OH 45268
Phone:(513)569-7491
wendelken.steve@epa.gov
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ii -!""• -ord
This document provides guidelines for the submission and validation of analytical methods under the
drinking water alternate test procedures (ATP) program. This ATP protocol provides guidance for the
modification or development of drinking water methods for compliance monitoring. It incorporates
current recommendations for method validation that have been developed by the Forum on
Environmental Measurements. Under the drinking water ATP program, applicants are required to
demonstrate that the alternate method being proposed is equally effective as an existing EPA-approved
method. This protocol provides basic information on the criteria the Agency generally uses in deciding
whether a method is suitable for evaluation under the ATP program and the analyses that are generally
needed to demonstrate method equivalency. In this protocol, applicants are also directed to
demonstrate adequate ruggedness of the ATP method through sufficient multi-laboratory validation to
support their use at a national level. The drinking water regulations are national standards and as such,
single laboratory or regional approvals are not permitted.
EPA anticipates that the standardized procedures described herein will expedite the processing of ATPs,
encourage the development of innovative technologies and enhance the overall utility of the EPA-
approved methods for compliance monitoring under the National Primary Drinking Water Regulations.
The Office of Ground Water and Drinking Water reviewed and approved this document for publication.
Neither the U.S. government nor any of its employees, contractors, or their employees make any
warranty, expressed or implied, or assumes any legal responsibility for any third party's use of, or the
results of such use, of any information, apparatus, product, or process discussed in this protocol. The
mention of company names, trade names or commercial products does not constitute an endorsement
or recommendation for use.
This document does not alter, substitute for, establish or affect legal obligations under Federal
regulations. This document is not a rule, is not legally enforceable, and does not confer legal rights or
impose legal obligations on any federal or state agency or on any member of the public. Interested
parties are welcome to suggest procedures that are different from what's recommended in this
document. EPA reserves the right to change this protocol without prior notice.
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Foreword ii
Disclaimer ii
1 Introduction 1
1.1 Background and Objectives 1
1.2 Scope of ATP 1
2 Overview of the ATP Process 1
2.1 Submission (initial application and subsequent documentation) 1
2.2 Application Information 1
2.2.1 Justification for ATP 2
2.3 Confidential Information in Applications 2
3 Method Development and Validation Study 3
3.1 Introduction 3
3.2 Development of a Validation Study Plan 3
3.2.1 Background 4
3.2.2 Study Management 4
3.2.3 Sample HoldingTime and Preservation 4
3.2.4 Method Procedures 4
3.2.5 Identification of Critical Steps and Plans for Addressing Critical Steps 4
3.2.6 Potential Interferences and Plans to Address Them 4
3.2.7 Demonstration Data 5
3.2.8 Fortified Reagent Water Analyses 5
3.2.9 Matrix Analyses 5
3.2.10 Quality Control 6
3.3 Method Validation Study Report 6
3.3.1 Background 6
3.3.2 Study Implementation 6
3.3.3 Detailed Method Procedure and Demonstration Data 7
3.3.4 Calculations, Data Analysis and Discussion 7
3.3.5 Conclusions 7
3.3.6 Validation Study Plan 7
4 EPA Review and Approval 7
4.1 EPA Review of Candidate ATP Method 7
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4.2 Approval Recommendation 7
4.3 Joint Drinking Water Wastewater Applications 8
Appendix A: Application and Document Submission Form A-l
Appendix B: Standard EPA Method Format B-l
Appendix C: Method Validation C-l
Table 1. Reference Values generally used for Drinking Water Method Development C-3
Appendix D: Validation Report Template D-l
IV
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1.1 I I i i"h I in ! Objectives
Pursuant to the Safe Drinking Water Act, EPA promulgates test procedures (analytical methods) for data
gathering and compliance monitoring under National Primary Drinking Water Regulations.
Under the Agency's ATP program, an organization may request evaluation of a method as an alternate
test procedure to a method already approved in the drinking water regulations. These alternate
methods will be referred to as "candidate" test methods through the remainder of this document. The
organization or entity seeking the evaluation is responsible for validating the candidate test method.
EPA evaluates test methods used to measure regulated contaminants in drinking water for nationwide
approval. Accordingly, EPA assesses any candidate test method in such a manner that its interlaboratory
range in accuracy, precision and detection capability can be compared to EPA approved test methods
measuring the same target analyte(s). To be considered for approval, the candidate test method must
be equally as effective as the approved method (see Safe Drinking Water Act §1401(1)); that is, the
method's performance characteristics in general must be equivalent to, or better than, those of existing
approved methods for the contaminant of interest. This allows EPA to ensure that data gathered under
the Safe Drinking Water Act are comparable on a nationwide basis. For those methods that demonstrate
acceptable performance through their ATP evaluation, EPA will initiate an appropriate approval action.
1,2 Scope of ATP
The ATP evaluation process is based on demonstrating ruggedness of a method (that is the method
yields reliable, accurate results over the range of field and lab conditions specified in the method) and
the use of designated quality control acceptance criteria against which ATP methods are tested for
equivalency relative to approved methods.
2 Overview oi l h< ,M hccess
Agency staff reviews the application, including justification for the ATP provided by the applicant and
determines whether an ATP evaluation is warranted. If the application is accepted for ATP
consideration, the applicant then develops a validation study plan in consultation with ATP staff. Once
the study plan is approved, the applicant performs the validation study and submits a validation study
report to the ATP program. If laboratory validation demonstrates performance equivalent to or better
than that obtained with an approved method, EPA will generally recommend approval using one of two
options: 1) approval through the conventional "notice and comment" rulemaking process, or 2) approval
through the expedited method approval process. Find additional information on UWsjJxgedJtedi
2.1 Submission (initial application and subsequent documentation)
Applicants should submit ATP applications (see Aj3|3eridix_A) to the Drinking Water ATP Coordinator.
Upon receipt of the application, the ATP staff will assign an identification number to the application. The
applicant should use the identification number and Appendix A as a cover sheet for all future
communications and any supplemental documentation concerning the application.
2,2 Application Information
Information required on the ATP application includes: the name and address of the applicant; the date
of submission of the application; the title of the proposed candidate method; the analyte(s) for which
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the ATP is proposed; a brief summary of the proposed method and the justification for proposing the
ATP. All required application information and any associated attachments should be submitted in order
for the application to be considered complete.
2.2.1 Justification for ATP
The applicant should provide a brief justification for why the ATP is being proposed. Because EPA review
and evaluation of proposed ATPs can entail considerable effort, EPA strives to minimize the submission
of impractical methods or method modifications that fall within the scope of flexible options already
allowed in an approved method or in EPA's "Technical Notes on Drinking Water Methods" (EPA
Document No. EPA-600-R-94-173, October 1994). Examples of appropriate justifications include but are
not limited to: the candidate method successfully overcomes some or all of the interferences associated
with the approved method; the candidate method reduces the amount of hazardous wastes generated
by the laboratory; the cost of analyses or the time required for analysis is reduced; or, the quality of the
data is improved.
It is highly recommended that the method developer consult with ATP staff concerning the proposed
candidate method and its justification prior to extensive method development.
2,3 Confidential Information in Applications
When you submit information with the proposed ATP application, you may, if you desire, assert a
business confidentiality claim covering part or all of the information. The method for submitting a claim
is described in the Code of Federal Regulations (CFR) at 40 CFR 2.203(b). EPA staff will handle such
information according to the regulations in subparts A and B of 40 CFR Part 2. Information covered by
such a claim will be disclosed by EPA only to the extent, and by means of the procedures, set forth in 40
CFR Part 2, Subpart B. If no such claim accompanies the information when it is received by EPA, it may
be made available to the public by EPA without further notice to the business.
Specifically, in accordance with 40 CFR §2.203(b), a business may assert a business confidentiality claim
covering the information by placing on (or attaching to) the information at the time it is submitted to
EPA, a cover sheet, stamped or typed legend, or other suitable form of notice employing language such
as trade secret, proprietary or company confidential. Confidential portions of otherwise non-confidential
documents should be clearly identified and may be submitted separately to facilitate identification and
handling by EPA. If confidential treatment is only required until a certain date, the notice should state so
accordingly. It should be noted, however, that any methods to be proposed for approval in the Federal
Register cannot themselves be claimed as confidential business information.
If a claim of business confidentiality is received after the information itself is received, EPA will make
such efforts as are administratively practicable to associate the late claim with copies of the previously
submitted information in EPA files. However, EPA cannot ensure that such efforts will be effective in
light of the possibility of prior disclosure or widespread prior dissemination of the information, See
§2.203(c).
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3 I I'Mlc ' I I v -p'f r i , h ,!u' , i , '
3.1 Introduction
Method development and validation is the process by which a laboratory substantiates the performance
of a method by demonstrating that the method can meet EPA's acceptance criteria and that the method
is rugged, that is, yields acceptable method performance and data quality over the range of drinking
water sample types and over the range of laboratory conditions specified in the method. In order to
produce a method that is rugged and meets quality control acceptance criteria, the method developer
needs to have a firm understanding of the chemistry involved in the method. Because methods vary
widely in their chemistry and procedures, no definitive global guidance can be provided on how to
develop a rugged method. In general, though, all candidate methods should: (a) identify critical points of
each step in the procedure, (b) demonstrate that these critical points are satisfactorily addressed or
controlled in the method and (c) demonstrate that acceptable method performance is attained using all
procedural options specified in the method.
Critical points of a method can take a variety of forms depending on the method. For example, certain
methods may require extraction of an analyte at a specific pH or narrow pH range. Thus, for the method
to be truly rugged, pH control (for example, use of buffers) may be required to ensure that other
samples, laboratory conditions or chemists obtain satisfactory results using the method. For candidate
methods intended to be used in the field, ambient temperature may be a critical factor affecting
performance of the method. The applicant should examine and control such factors or limit the
conditions under which the method can be used. Other examples of critical steps requiring ruggedness
demonstration are:
• Determination of the breakthrough volume in solid phase extraction.
• Effect of laboratory temperature on a purge and trap method.
• Determination of a critical solvent to sample ratio in liquid-liquid extraction.
Many methods have procedural options in certain steps, for example, a choice of two sample
preservation agents. If more than one preservation option is specified in a candidate method, the
applicant must demonstrate acceptable method performance using both preservation options. Similarly,
if a candidate method specifies either of two different solid phase sorbents for extraction, the applicant
must demonstrate acceptable performance using both sorbents.
Once an application has been accepted by the ATP program, the applicant should discuss their plans to
address method ruggedness with ATP staff prior to formulating the validation study plan. Such
consultation will help avoid both inadequate study plans (for example, not enough analyses addressing
critical points of the method) and study plans with unnecessary analyses. The following sections
summarize the major components of the validation study plan.
3.2 ID eve I o p irn e in t of a Va I i d a tii o in St u d y IP I a in
Prior to conducting the candidate method validation study, the applicant should prepare and submit a
detailed study plan for EPA approval. Guidelines describing the parameters that should be addressed in
a method validation study are provided in AjD]Dendix_C. In general, the validation study plan will consist
of the following sections.
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3.2.1 Background
The Background section of the validation study plan should:
• Include a summary of the candidate method.
• List the analytes measured by the candidate method including corresponding Chemical
Abstracts Service Registry identification.
3.2.2 Study Management
The Study Management section of the validation study plan should:
• Identify the organization responsible for managing the study.
• Identify the laboratories or other organizations that will participate in the study.
• Delineate the study schedule.
3.2.3 Sample Holding Time and Preservation
In general, candidate methods are expected to use the sample holding times, extract holding times (if
applicable) and preservation agents specified in approved EPA methods for the analyte, unless these
parameters are being explicitly modified in the candidate method. If no changes to holding times or
preservation are proposed in a given candidate method and no additional analytes are being added to a
method, then this part of the validation study plan is likely to require little discussion. If however, the
proposed candidate method alters, or could affect holding times or the preservation of the sample, a
holding time or preservation study or both will be required.
3.2.4 Method Procedures
This section of the validation study plan details the step-by-step procedures of the candidate method.
This includes all equipment, reagents and materials required and data evaluation or calculation
procedures. Unless the applicant is a consensus standards organization or government organization that
has their own method format requirements, all applicants should submit the candidate method written
in the standard EPA method format. Applicants from organizations having their own format
requirements should compare their specific method format with the EPA method format to ensure that
all sections of the EPA method format are addressed. The 17 sections listed in Aj3j3end]xj| of this
document should be included for all candidate test methods. Recent drinking water methods published
by EPA (for example, methods 524.3, 525.3) may also be consulted for format and the level of detail
required.
3.2.5 Identification of Critical Steps and Plans for Addressing Critical Steps
As mentioned previously, a properly developed and validated method recognizes and controls critical
steps in terms of the chemistry or ruggedness, or both, of the method. The applicant should make every
attempt to identify those parts of the procedures that could be vulnerable to technician expertise or
result in poorer performance with slight but realistic departures from ideal conditions. The Plan should
identify, when possible, the steps that will be taken to control these critical steps.
3.2.6 Potential Interferences and Plans to Address Them
Many chemical methods are subject to chemical or physical interferences or both which, if left
uncontrolled, result in inaccurate monitoring results. Through an understanding of the chemistry of the
method, the applicant should identify potential interferences to the candidate method and plans to
address and control these interferences.
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3.2.7 Demonstration Data
In this section, the applicant will specify the data to be collected using the candidate method and the
approved reference method. Generally, all candidate methods will determine precision and accuracy of
the method using both fortified reagent water and different real or synthetic drinking water matrices.
Synthetic drinking water matrices should be prepared to provide objective evidence of method
capabilities in a "worst case" situation (for example, high hardness or ionic strength and high total
organic carbon.)
3.2.3 Fortified Reagent Water Analyses
Generally, ATP candidate methods are required to determine precision, accuracy and sensitivity in
reagent water fortified with the contaminant(s) of interest at relevant concentrations. Accordingly,
multiple replicates at the relevant concentration levels will be needed. Concentration levels evaluated in
the precision and accuracy studies are expected to extend both above and below the published
regulatory Maximum Contaminant Level effectively demonstrating the candidate method will satisfy all
regulatory measurement requirements.
Fortified reagent water samples should incorporate the preservation agent(s) specified in the method
and any other reagents or treatments specified in the method. Fortified reagent water samples should
be prepared and analyzed for every option specified in the method. For example, if two or more
preservation agents are specified as options in the method, reagent water analyses should be
performed using each preservation agent given in the method.
3.2.9 Matrix Analyses
For ATP candidate methods, precision and accuracy should be examined using different drinking water
matrices that may be encountered during routine sample analysis. These drinking water matrices may
be actual or synthetic and the exact number and type needed will be determined when the validation
study plan is constructed. Generally the matrices are a combination of the following types: (1) finished
drinking water drawn from a hard ground water source (hardness > 250 mg/L as CaCO3), (2) finished
drinking water drawn from a surface water source and containing total organic carbon (TOC > 2 mg/L),
(3) artificial drinking water matrix high in ionic strength and (4) artificial drinking water matrix high in
organic content. Additional matrices may need to be examined to document adequate performance of
the method as appropriate. For example, if chloride is known or suspected to interfere with a given
method, the validation study plan may need to include a public water supply sample or artificial matrix
having the maximum, tolerable chloride concentration that the applicant has determined for the
candidate method. If a method is designed to measure a particular disinfection byproduct it may be
necessary to examine various finished drinking waters to adequately test the method. ATP staff will
work with the applicant to determine appropriate matrices to include in the validation study plan.
Analysts should review an applicable approved or published method for indications of matrix effects
that are unique to the analyte separation and measurement technologies used in the ATP. Water quality
characteristics that can affect analysis of drinking water samples include, but are not limited to, pH, total
organic carbon content, turbidity, total organic halogen content, ionic strength, sulfate, metal
contamination and trihalomethane contamination of the drinking water sample.
For each drinking water matrix specified in the validation study plan, replicates are fortified at a
concentration sufficiently below the Maximum Contaminant Level, along with a midrange and a high
level spike. Precision and accuracy are determined for each set of replicates. As noted above for reagent
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water analyses, additional replicates or fortified concentration levels may be required depending on the
method. Also, as noted previously, each sample is tested using any and all options specified in the
candidate method.
3.2.10 Quality Control
Quality control is an important aspect of method performance. Quality control needs to be incorporated
within each ATP candidate method and the applicant should address the quality control specified in the
method. Common quality control parameters include:
• Initial calibration and calibration verification.
• Blanks.
• Ongoing precision and accuracy.
• Surrogate recovery.
• Internal standard response.
• Fortified matrix precision and accuracy.
summarizes the above quality control parameters as they are addressed for organic
and inorganic contaminants in EPA drinking water methods.
33 Method Validation Study Report
The applicant should document the results of the validation study in a formal validation study report
containing the elements described in this section. In all cases, a copy of all required validation data
should be maintained at the laboratory or other organization responsible for developing the method.
The information and supporting data in the validation study report must be sufficient to enable EPA to
support an equivalent method performance determination, relative to an approved method.
Consistent with the validation study plan, the validation study report contains background information
and describes the study design. In addition, the validation study report details the process and results of
the study, provides an analysis and discussion of the results and presents study conclusions. The
approved validation study plan should be appended to and referenced in, the validation study report.
The validation study report should identify and discuss any deviations from the validation study plan
that were made in implementing the study along with problems encountered and corrective actions.
3.3.1 Background
The Background section of the validation study report describes the candidate method. The Background
section of the validation study report should:
• Include a method summary.
• Summarize the justification for the ATP evaluation and the proposed benefits the candidate
method offers to drinking water monitoring.
• List the analytes measured by the candidate method, including corresponding Chemical
Abstracts Service Registry identification.
3.3.2 Study Implementation
The Study Implementation section of the validation study report describes the methodology and
approach undertaken in the study. This section should:
• Identify the laboratories or other organizations or both that participated in the study.
• Delineate the study schedule that was followed.
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• Explain how samples were collected and handled.
• Specify the numbers and types of analyses performed by the laboratory.
• Identify any problems encountered or deviations from the study plan and their resolution or
impact on study performance or results or both.
3.3.3 Detailed Method Procedure and Demonstration Data
This section of the validation study report presents a detailed version of the method. Format should
follow that specified in AjgjaendixJI. Following the detailed method, the report should include the
demonstration data for the analyzed samples. For each sample, the report should compare method
performance data obtained with the candidate method to the approved reference method performance
data. Demonstration data should be provided for samples using all procedural options specified in the
method.
3.3.4 Calculations, Data Analysis and Discussion
This section of the validation study report should provide sufficient documentation of the data obtained
with the candidate method to permit an independent reviewer to verify the study results. Example
calculations are required as part of the results and should be included in the validation study report. The
test data and calculations should be electronically reported in a format compatible with Microsoft Office
applications. The discussion should address any discrepancies between the results and the quality
control acceptance criteria.
3.3.5 Conclusions
The Conclusions section of the validation study report describes the conclusions drawn from the study
based on the data analysis discussion. The Conclusions section should contain a statement(s) regarding
achievement of the study objective(s).
3.3.6 Validation Study Plan
The approved validation study plan should be appended to the validation study report.
i M • !\ , ie\A 'h : ,(,'M - J
II ! I I I - -new I iiv iih! in 11 Method
EPA's ATP program reviews the drinking water ATP candidate methods and the validation data. If a
candidate method is determined to provide equivalent method performance relative to an approved
reference method, it will be recommended for approval.
4.2 Approval Recommendation
EPA will complete its review and notify the applicant of EPA's recommendation. If the candidate test
method is recommended for approval, EPA will pursue formal approval using one of two options: 1)
approval via the conventional "notice and comment" rulemaking process or 2) approval via the
expedited method approval process. Find additional information on ^PA^s_e)
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4.3 Joint Drinking Water Wastewater Applications
Candidate methods can be submitted for ATP evaluation for both drinking water and wastewater
applications. However, the requirements for compliance monitoring under the National Primary
Drinking Water Regulations differ from those under the National Pollutant Discharge Elimination System
permit program. Review and evaluation of ATP candidate methods that are submitted for dual
applications are thus handled separately by the Drinking Water ATP program and the Wastewater ATP
program.
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Appendix
EPA Office of Ground Water and Drinking Water
Alternate Test Procedure Candidate Method Application
D Initial Application
D Supplemental Documentation
D Final Application
Applicant Information
Applicant Name:
Address:
State:
Zip Code:
Contact name:
Phone number:
Email address:
Submission Date:
Candidate method:
Analyte(s):
Candidate test method title:
Reference method number or name or both:
Attachments
D Justification for Candidate Test Method
D Validation Study Plan
D Validation Study Report
D Raw Data Package (spreadsheets, calibrations, etc.)
D Data Collection Certification
D Other Documentation:
EPA use only
Case number:
A-l
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Appendix B: Standard EPA Method Format
[Note: Each method should be a free-standing document, providing all information necessary for the
method user to perform the method. References within a method should be restricted to associated or
source material. Procedural steps or instructions should not be referenced as being found elsewhere, but
should be included in totality within the method.]
1 Scope and Application
[This section outlines the purpose, range, limitations, and intended use of the method and identifies
target analytes.]
2 Summary of M-1 i iod
[This section provides an overview of the method procedure and quality assurance.]
3 Definitions
[This section includes definitions of terms, acronyms and abbreviations used in the method. If preferred,
definitions may be provided in a glossary at the end of the method or manual. In this case, the
definitions section should still appear in the method, with a notation that definitions are provided in a
glossary (refer to the specific section number of the glossary) at the end of the method.]
4 Interferences
[This section identifies known or potential interferences that may occur during use of the method and
describes ways to reduce or eliminate these interferences.]
5 :-J|.M\
[This section describes special precautions needed to ensure personnel safety during the performance
of the method. Procedures described here should be limited to those which are above and beyond good
laboratory practices. The section should contain information regarding specific toxicity of analytes or
reagents.]
6 Equipment and Supplies
[This section lists and describes all non-consumable supplies and equipment needed to perform the
method.]
7 Reagents and Standards
[This section lists and describes all reagents and standards required to perform the method and provides
preparation instructions or suggested suppliers or both as appropriate.]
8 !.'>['' i! , i %l I > "•> ,11, .'I,! ^ i ^ ,
[This section provides requirements and instructions for collecting, preserving and storing samples.]
B-l
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[This section cites the procedures and analyses required to fully document the quality of data generated
by the method. The required components of the laboratory's quality assurance program and specific
quality control analyses appropriate to the method are described in this section. It should at least
address the quality control specifications listed in A£ge_ndi^QJ^ab|e_jl of this document.]
[This section describes the method or instrument calibration and standardization process and the
required calibration verification. Corrective actions are described for cases when performance
specifications are not met.]
11 Procedure
[This section describes the sample processing and instrumental analysis steps of the method and
provides detailed instructions to analysts.]
12 Data / ,r. J1: i ^ ,-nJ ' J- "| ,[iv,|,
[This section provides instructions for analyzing data, equations, and definitions of constants used to
calculate final sample analysis results and their uncertainties.]
13 Method Performance
[This section provides method performance criteria for the method, including precision or bias
statements regarding detection limits and sources or limitations of data produced using the method.]
i h
[This section describes aspects of the method that minimize or prevent pollution known to be or
potentially attributable to the method.]
15 Waste Management
[This section describes minimization and proper disposal of waste and samples.]
lt • I i ices
[This section lists references for source documents and publications that contain ancillary information.]
[This section contains all the method, tables, figures, diagrams, example forms for data recording and
flowcharts. This section may also contain validation data referenced in the body of the method.]
B-2
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Appendix C: Method Validation
Method validation is the process of demonstrating that an analytical method is suitable for its intended
use and involves conducting a variety of studies to evaluate method performance under defined
conditions. Method validation studies may involve a single laboratory (intralaboratory) or multiple
laboratories (interlaboratory). The goal is to demonstrate that analytical results produced by the
application of a particular method are fit for an intended purpose. Properly designed and successful
method validation studies create confidence in the reliability of a test method. Method validation is one
of several important quality system components that are designed to ensure the production of
scientifically valid and useful analytical data.
The information in this appendix is intended to serve as a guideline only. Because methods vary
significantly in chemistry and technology it is not possible to define a single set of performance criteria
that can be applied to all methods. This is due to the severe problems in translation of a complex
domain of knowledge such as analytical chemistry into a mathematical statement. This appendix lists
critical elements of the general method validation process that may not apply in all cases. The actual
validation components that will be necessary will be determined during the creation of the method
validation study plan.
Storage Stability
Before validating an analytical method, it is necessary to ensure that proper sample preservation and
storage stability studies were performed during method development. Storage stability should
investigate the stability of the analyte(s) from the time of sampling through the time of analysis. If an
extraction is performed, the extract stability should also be investigated. Analytes may be lost through
volatilization, sorption, chemical degradation (abiotic reactions) and microbial degradation.
Traditionally, preservation to prevent chemical degradation is evaluated but preservation to prevent
microbial degradation has been historically ignored. Microorganisms have the potential to degrade
target analytes and represent a significant pathway for the fate and destruction of organic compounds.
Instrum in • • hLiatiion
Instrument calibration refers to the procedures used for correlating instrument response to an amount
of analyte (concentration or other quantity). The characteristics of a calibration function and
justification for a selected calibration model should be demonstrated during a method validation study.
The performance of a calibration technique and the choice of calibration model (for example, first order,
second order, weighting, etc.) are critical for minimizing sources of instrument bias and optimizing
precision. The parameters of the model are usually estimated from the responses of known, pure
analytes. Calibration errors can result from failure to identify the best calibration model; inaccurate
estimates of the parameters of the model; or inadequately studied, systematic effects from matrix
components.
During method development and validation, calibration models are typically evaluated by analyzing
multiple levels of calibration standards over a selected working range. After a calibration curve is
constructed from the responses, the concentrations of the standards are calculated from the curve.
These values are then compared to the appropriate quality control criteria to determine the curve's
adequacy. The calibration study results should be included in a method validation report. Access to
C-l
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information about calibration performance characteristics assists the user in implementing new
methods and verifying that a laboratory's instrument performance is acceptable.
Accuracy (Bias)
Bias refers to the overall magnitude of known systematic (determinate) errors associated with the use of
an analytical method. The presence of systematic errors can only be determined by comparison of the
average of many results with a reliable, accepted reference value. Method bias may be estimated by
measuring materials whose composition is reasonably well known or by analyzing fortified materials.
Rigorous evaluations of bias should be included in method validation studies. Minimally, bias should be
evaluated at the extremes of the quantitation range, at regulatory levels and in representative matrices.
IP red si on
The general term "precision" is used to describe the magnitude of random (indeterminate) errors
associated with the use of an analytical method. The sources of random error evaluated depend upon
the range of conditions over which the data are collected.
Precision should be evaluated at the extremes of the quantitation range, at regulatory levels and in
representative matrices. Common measures of dispersion are the standard deviation and the percent
relative standard deviation of repeated measurements. The repeatability and reproducibility conditions
should be clearly stated so that the measures of dispersion can be properly interpreted and evaluated.
Quantitation I limits and Range
The term "quantitation range" is used to describe the span of analyte levels, as contained in a sample
matrix, for which method performance has been tested and data quality is deemed acceptable for its
intended use. For compliance, a quantitation range includes either a regulatory or other type of action
level for the compound being analyzed.
A lower limit and an upper limit bound a quantitation range. A quantitation range may be wider than an
instrument's calibration range because of dilution or concentration steps performed during sample
preparation. Dilution factors or concentration factors are used to relate the calibration range to the
quantitation range. Analyte concentration will have an effect on most method performance
characteristics, including bias and precision. At a minimum, method bias and precision should be
evaluated at the extremes of the quantitation range.
The lower limit of the quantitation range is commonly referred to as the "limit of quantitation." The
method reporting limit should always be above the "limit of quantitation" and both should be at or
above the lowest calibration standard.
Detection Limit(s)
The term "detection limit" is used to describe the lowest analyte level that can be confidently identified.
There are many specific definitions for this term and it is used to describe the detection capabilities of
detectors, instruments and analytical methods. Currently Office of Ground Water and Drinking Water is
trying to phase out the use of detection limits and focus more on the application of method reporting
limit. Where they are still required by regulation the procedure described at 40 CFR, Part 136, Appendix
B is being used to determine them.
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R u gged in ess Testii in g
Ruggedness refers to the extent to which an analytical method remains unaffected by minor variations
in operating conditions. Ruggedness testing involves experimental designs for examining method
performance when minor changes are made in operating or environmental conditions. The changes
should reflect expected, reasonable variations that are likely to be encountered in different laboratories.
Ruggedness testing is generally conducted at the end of method development but before an
interlaboratory method validation study.
Quality Control Targets for Method Development
As previously mentioned, the necessary validation components will be determined during the creation
of the method validation study plan. This includes the numeric limits for specific quality control
parameters. These values will depend on the regulation, intended data use, the quality control
parameters for existing reference methods and the individual technology that is being applied. Table 1
provides reference values that are generally used by Office of Ground Water and Drinking Water for
method development.
Table 1. Reference Values generally used for Drinking Water Method Development
Parameter
Method Blank
Initial Demonstration
of Capability Accuracy
or bias, Continuing cal
checks and Calibration
curve checks (as %
recovery)
Surrogate Recovery
Initial Demonstration
of Capability Precision
and Duplicate Samples
(% Relative Standard
Deviation)
Internal Standard
Organic Methods
< 1/3 MRL
>2xMRL±30%, <2x
MRL ±50%
±30%
±30%
> 50% of the Internal
Standard area or
response in the active
calibration
Inorganic Methods (Ion
Chromatography or
wet)
< 1/3 MRL
>2xMRL±15%, <2x
MRL ±20%
± 15%
±20%
Same
Metals or Inductively
Coupled Plasma
< 1/3 MRL
>2xMRL±10%, <2x
MRL ±20%
Not Applicable
± 15%
60%-125%
Additionally, the general validation study would require the method to be evaluated by two independent
certified laboratories in addition to the vendor's lab.
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Appendix D: Validation Report Template
Microsoft© Word
This template is to be used to prepare final validation study reports for ATPs. The template sets up the
primary validation study report sections along with brief instructions for each section. The template is
prepared using an Adobe®-supported font for proper .pdf conversion. Please do not make any changes
to fonts or styles.
If the alternate test method demonstrates equivalency to an approved method, EPA may grant formal
approval for compliance monitoring through either conventional notice-and-comment rulemaking or
through the expedited methods approval process. In either case, this validation report will be
incorporated in the public docket associated with the approval action.
If typing the validation study report directly into the template, replace the text of the template and
begin typing your report (that is, select the Title section and replace it with your title). This page of
instructions can be deleted upon completion of the validation study report.
Insert graphics within the text in TIFF, JPEG or Microsoft© Office compatible file format (*.wmf or
*.emf).
Save the file with the graphics in place as a document file (.doc).
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Alternate Test Procedure (ATP) Validation Study Report
Title
[The title should clearly and concisely specify the name of the method, the scope of the measurement
(for example, "measurement of turbidity", "nitrate analysis", etc.) and the instrumentation (if
applicable).]
Date
Name and address of organization
Author name(s)
[Include individual(s) with responsibility for overseeing development of the alternate test method and
verifying accuracy of the data presented in the validation study report. Designate the appropriate point
of contact in the event questions arise after review of the report.]
Phone number and email address
[Author or point of contact phone number and email address.]
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1 Background
[Provide a method summary discussing the experimental technique.]
1,1 Method Justification
[Specifically cite the approved method that the alternate method is being compared to: cite the
organization (for example, ASTM, Standard Methods, EPA, etc.) and the method number. Summarize
justification for the ATP and describe the advantages the new method affords relative to the approved
method, especially in terms of improved sample throughput, reduction of hazardous waste, cost
reduction, elimination of interferences, etc.]
1,2 Met IT -1 I "]ui valency
[Summarize the quality control acceptance criteria as defined in the approved method and describe how
the alternate method meets these specifications. Clearly indicate in the final sentence whether the
alternate method is "equally effective" in meeting quality acceptance criteria as the approved method.]
1.3 Analytes
[Identify the analytes that are determined using the alternate method and list the corresponding
Chemical Abstracts Service registry numbers.]
2 .Study Implementation
[Clearly identify the managing organization responsible for development of the alternate test method
validation study plan and all of the laboratories participating in the study. Explain why specific
laboratories were selected to participate and whether they received compensation for the work
performed. Identify whether the study involved the use of different types of instrumentation (for
example, gas chromatography-mass spectrometry analyses using ion trap detectors and triple
quadrupole detectors).]
2.1 Study Schedule
[Delineate the study schedule.]
2,2 Sample Collection
[Describe how samples were collected and handled. Specify whether required holding times were met.]
2,3 Types of Analyses Performed
[Describe the number and types of analyses performed by each laboratory (for example, specify how
many replicate analytical runs were performed to evaluate precision and accuracy in each drinking
water matrix, incorporation of blanks, etc.]
2.4 Study Plan Deviations
[Fully describe any problems encountered or deviations from the study plan and the resolution or
impact of these issues on the study plan performance results.]
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3 i ' •
[The alternate method should be prepared in standard EPA method format and submitted with the
initial validation study plan. In this final validation report, the method should be attached as an
addendum and referenced as such in this section. Compare and contrast procedural differences
between the alternate method and the approved method.]
3.1 Validation Study Demonstration Data
[Submit complete demonstration data for both reagent water and drinking water matrix analyses in
tables, graphs or figures, as appropriate. The data should clearly present the alternate method data in
comparison with the required reference method quality control criteria. Address the items in the
following subsections, as appropriate.]
3.1.1 Calibration
[Demonstrate acceptable calibration performance as defined in the validation study plan. Include
calibration verification through incorporation of calibration checks.]
3.1.2 Initial Demonstration of Capability
[Demonstrate acceptable low system background, precision and accuracy and detection limit or
minimum reporting level confirmation (as specified in the validation study plan).]
3.1.3 Quality Controls
[Include verification of method performance through the use of blanks, surrogates, internal standards
and other quality controls as specified in the validation study plan.]
3.1.4 Precision and Accuracy
[Include all precision and accuracy data for reagent water and drinking water matrix samples.]
3.2 Hoi" IINI i I in HI'S r Storage Stability
[If specified in the validation study plan, submit storage stability data. Otherwise, indicate that a holding
time study was not required.]
4 Data Analysis and Discussion
[Provide a comparison of the alternate method data to the approved method to confirm equivalency of
performance. Discuss in detail any discrepancies between the results and quality control acceptance
criteria. Discuss method ruggedness based on overall performance as specified in the validation study
plan (for example, multi-laboratory studies, analyses performed on multiple instruments, assessments
of various drinking water matrices, etc.)]
I, J
[Discuss achievement of validation study objectives.]
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Appendix «kl ,u i. i'\! i I
[Append the approved validation study plan.]
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Raw Data
[Submit raw data in an excel spreadsheet. Identify instruments used and operating conditions,
chromatographic column specifications, high-performance liquid chromatography gradients, gas
chromatography temperature programs, detectors, injection volumes, solid phase extraction media and
extraction procedures.]
IE xa irn p I e Ca I c u I a tii o in s
[Provide sample calculations to verify that the laboratory has used the raw data to correctly arrive at the
final results.!
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M iii (cation
It is the expectation of the ATP program that all data will be collected as outlined in the validation study
plan. Applicants must attest on the application that the data collection was performed as outlined in the
validation study plan.
The applicant hereby certifies that the data included with this application were collected as outlined in
the validation study plan.
Applicant (print name)
Applicant (signature) and (Date)
[Questions, comments or applications should be directed to:
Steven C. Wendelken^j^hD.
U.S. EPA, OGWDW-TSC
26 W. Martin Luther King Dr.
Cincinnati, OH 45268
Phone:(513)569-7491
Fax:(513)569-7837
wendelken.steve@epa.gov]
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