1、 Analytical Detection and Quantification Limits: Survey of State and Federal ApproachesRegulatory Analysis and Scientific AffairsPUBLICATION NUMBER 4721JUNE 2002Analytical Detection and Quantification Limits:Survey of State and Federal Approachesprepared forAmerican Petroleum Institute1220 L Street
2、NWWashington, DC 20005prepared byTischler/Kocurek107 South Mays StreetRound Rock, TX 78664Detection/Quantification Limits Review iACKNOWLEDGMENTSTHE FOLLOWING PEOPLE ARE RECOGNIZED FOR THEIR CONTRIBUTIONS OF TIME ANDEXPERTISE DURING THIS STUDY AND IN THE PREPARATION OF THIS REPORT:API STAFF CONTACTR
3、oger Claff, Regulatory Analysis and Scientific AffairsMEMBERS OF THE CLEAN WATER ISSUES TASK FORCEDavid Pierce, Chairman, ChevronTexaco CorporationGary Morris, Vice-Chairman, ExxonMobil CorporationYvette Baxter-Drayton, BP P.L.C.Deborah Bolton, ChevronTexaco CorporationPaul Cole, ExxonMobil Corporat
4、ionJohn Cruze, Phillips Petroleum CompanyClay Freeburg, ChevronTexaco CorporationRobert Goodrich, ExxonMobil Research and EngineeringLeanne Kunce, BP P.L.C.Rees Madsen, BP P.L.C.Jonnie Martin, Equiva Services LLCGreg Moore, Marathon Ashland Petroleum LLCPat Netsch, ChevronTexaco CorporationMichael P
5、arker, ExxonMobil CorporationJames Robinson, BP P.L.C.James Scialabba, Marathon Oil CompanyPaul Sun, Equilon Enterprises LLCPeter Velez, Shell Exploration and Production CompanyDetection/Quantification Limits Review iiAbstractAs analytical methods and technologies continue to improve, and traceconce
6、ntrations of pollutants in ambient waters are better quantified, regulatory agenciesare increasingly setting effluent permit limits for some pollutants near analyticaldetection limits, and establishing policies for determining compliance with these stringentlimits. The American Petroleum Institute (
7、API) conducted a review of state policiesrelated to analytical detection and quantification limits, with particular focus on waterquality and wastewater issues in permitting and compliance. Of the ten states consideredin this review, every state was found to incorporate detection or quantification t
8、erms in itsregulations to some extent. Some of the states prefer to have the most detailed policies intheir water quality implementation procedures; other states prefer to put the detail directlyin the regulations. Most of the states specify, either in their regulations orimplementation procedures,
9、how compliance is demonstrated. Permittees can ensure thatthey obtain permit limits that do not cause compliance monitoring problems by payingparticular attention to effluent data during the permit application process, by identifyingearly in the permitting process the need for site-specific detectio
10、n and quantificationlimits, and by understanding the states permit requirements and policies specifying howcompliance is to be demonstrated.Detection/Quantification Limits Review iiiTable of ContentsExecutive Summary 1Introduction 2Overview of Report. 2Overview of Approaches. 2State Policies 8Recomm
11、endations for Compliance Monitoring . 29AppendixList of State Regulations Citing Detection/Quantification Terms . 31Tables1 Detection and Quantification Terms 32 Other Detection and Quantification TermsUsed in Federal Water and Wastewater Programs 43 Comparison of Detection and Quantification Terms
12、94 Detection and Quantification Terms Used in Other Federal Programs 125 Summary of Analytical Detection and Quantification Terms Used by States . 151Analytical Detection and Quantification Limits:Survey of State and Federal ApproachesExecutive SummaryThe American Petroleum Institute (API) conducted
13、 a review of state policiesrelated to analytical detection and quantification limits, with particular focus on waterquality and wastewater issues in permitting and compliance. Ten states were reviewed:Alabama, California, Illinois, Louisiana, New Jersey, Ohio, Oklahoma, Pennsylvania,Texas, and Washi
14、ngton.Summary findings of this review are: Every state incorporates detection or quantification terms in its regulations.Terms referenced in regulations are usually defined in the regulations, but notalways. The most frequently used terms are detection limit/level, methoddetection limit (MDL), and p
15、ractical quantitation level (PQL). Minimum level(ML) is used by Alabama, California, Illinois, and Ohio. The states vary in the extent to which detection and quantification terms areincorporated into their regulatory language. Some states prefer to have themost detailed policies in their water quali
16、ty implementation procedures; otherstates prefer to put the detail directly in the regulations. The states will set wastewater permit limits at or below detection orquantification levels, where considered protective of water quality. Moststates specify, either in their regulations or implementation
17、procedures, howcompliance is demonstrated in such cases. Compliance with a maximumconcentration limit is demonstrated by a less-than analytical result (adetection or quantification limit, as applicable). Where a mass load or averageconcentration is calculated, most states specify that zero be used i
18、n lieu ofless-than values. In some situations, one-half the detection limit must be used. Although the states have procedures for allowing wastewater permittees todevelop site-specific detection or quantification limits based on state- or EPA-defined methods, none of the states had specific procedur
19、es for developing orapproving alternative methods. State staff indicated that approval ofalternative methods would be on a case-by-case basis, and likely coordinatedwith the USEPA. Permittees can ensure that they obtain permit limits that do not causecompliance monitoring problems related to detecti
20、on and quantificationissues. During the permitting process, permittees should pay particularattention to effluent data in the application, the need for site-specific detectionand quantification limits or procedures, and permit requirements specifyinghow compliance is to be demonstrated.2Introduction
21、The purpose of this review was to determine the analytical detection andquantification limit policies of various state agencies. Of particular interest were policiesfor setting wastewater discharge permit limits at or below detection or quantificationlimits, for determining compliance with such limi
22、ts, and for using alternative approachesto determining detection or quantification limits. Although the main focus of this reviewwas on state policies involving water quality issues, included in the review were thepolicies of programs in other environmental areas as well as in federal regulations an
23、dstatutes.Ten states were selected for review: Alabama, California, Illinois, Louisiana, NewJersey, Ohio, Oklahoma, Pennsylvania, Texas, and Washington. State environmentalregulations and water quality implementation procedures were reviewed, and stateenvironmental staff were contacted and interview
24、ed, to obtain information on detectionand quantification limit policies.Overview of ReportPresented first is an overview of approaches for analytical detection andquantification limits in environmental programs. The overview describes variousdetection and quantification terms, including method detec
25、tion limit (MDL), minimumlevel (ML), practical quantitation (or quantification) level (PQL), alternative minimumlevel (AML), interlaboratory quantification estimate (IQE), and others. Next, the policiesof the ten selected states are presented. Lastly, recommendations are provided for settingeffluent
26、 limits and compliance monitoring requirements in wastewater discharge permits.Overview of ApproachesThis section provides an overview of selected approaches for determining analyticaldetection and quantification levels used in environmental programs. Table 1 lists theterms most often used in these
27、programs, as well as two alternatives (AML, IQE) thathave been suggested by others. In the following sections, these terms, as they are used inwastewater programs, are discussed in detail, and their similarities and differences arecompared. Terms used in other environmental programs, both state and
28、federal, areidentified.Water and Wastewater ProgramsThe most common detection and quantification limits in water and wastewaterprograms are the MDL, ML, and PQL. The MDL can be used to calculate both the MLand the PQL. Variations of these and other related terms can be found in water andwastewater p
29、rograms. Definitions of these terms as given in the regulations are provided3Table 1Detection and Quantification TermsDetection TermsDL Detection limitLOD Limit of detectionMDL Method detection limitQuantification TermsAML Alternative minimum levelIQE Interlaboratory quantification estimateLOQ Limit
30、 of quantitationML Minimum levelPQLPractical quantitation levelPractical quantification levelin Table 2; no references to analytical detection terms were found in federalenvironmental statutes. These basic definitions are discussed in the following sections.Detection LevelsThe USEPA has a specific d
31、efinition of the MDL in its regulations. Among thevarious state and federal programs, there may be modifications to this definition orreferences to other detection terms (some defined and some not).Method Detection Limit (MDL)The MDL is a detection term defined by the USEPA as:the minimum concentrat
32、ion of a substance that can be measured and reportedwith 99% confidence that the analyte concentration is greater than zero and isdetermined from analysis of a sample in a given matrix containing the analyte.40 CFR 136, Appendix BThe typical MDL procedure is to analyze seven aliquots of a sample at
33、a lowconcentration, 1 to 5 times the estimated MDL. The MDL can be measured in reagentwater (water with no impurities) or in any wastewater matrix (matrix-specific MDL). Ifthe sample does not already contain the analyte in this concentration range, it is spikedwith the analyte. The standard deviatio
34、n of the seven analytical values is calculated. The4Table 2Other Detection and Quantification TermsUsed in Federal Water and Wastewater ProgramsTerm Definition ReferenceDrinking WaterDetection level The lowest concentration of a targetcontaminant that a given method or piece ofequipment can reliably
35、 ascertain and report asgreater than zero (e.g., instrument detectionlimit, method detection limit, or estimateddetection limit).40 CFR 141.35Practical quantitation level No definition given in regulations 40 CFR 141.8140 CFR 141.89Effluent GuidelinesInstrument detection limit No definition given in
36、 regulations 40 CFR 430,Appendix AMethod detection limit The minimum concentration of a substancethat can be identified, measured and reportedwith 99 percent confidence that the analyteconcentration is greater than zero anddetermined from analysis of a sample in agiven matrix containing analyte sic.
37、40 CFR 425,Appendix CMethod detection limit No definition given in regulations 40 CFR 434.64Pretreatment StandardsAnalytical detection limit No definition given in regulations 40 CFR 403.6Water Quality StandardsQuantification level A measurement of the concentration of acontaminant obtained by using
38、 a specifiedlaboratory procedure calibrated at a specifiedconcentration above the method detectionlevel. It is considered the lowest concentrationat which a particular contaminant can bequantitatively measured using a specifiedlaboratory procedure for monitoring thecontaminant.40 CFR 132.2Minimum le
39、velQuantification levelThe minimum level (ML) specified in orapproved under 40 CFR 136 for the methodfor that pollutant. If no such ML exists, or ifthe method is not specified or approved under40 CFR 136, the quantification level shall bethe lowest quantifiable level practicable.40 CFR 132,Appendix
40、FMDL is calculated as the standard deviation multiplied by the Students t value for the99th percentile (3.143 for seven analyses).Limit of Detection (LOD)The LOD is defined by the American Chemical Society (ACS) as:5the lowest concentration level that can be determined to be statisticallydifferent f
41、rom a blank.ACS 1983, pg. 2216The LOD is calculated as three times the standard deviation, s, at either zero (blank) orthe lowest level of measurement. It differs from the USEPAs MDL in the multiplyingfactor 3 versus 3.143 (or other Students t value) and in not having a recommendednumber of replicat
42、e analyses. Use of s, the population standard deviation, implies aninfinite number of analyses, or at least a very large number. In practice, the samplestandard deviation, s, would be used as a substitute for s.Other Detection TermsOther detection terms used in state programs are discussed in the se
43、ction on StatePolicies. Those found in federal regulations are listed in Table 2.Quantification LevelsThe USEPAs approaches to the ML and PQL are described in the followingsections. Although the term LOQ is not used per se in these programs, a description ofthe term is also provided because of its r
44、elation to the ML. The AML and IQE, whichhave been promoted to the USEPA as improved quantification levels, are also described.Following these descriptions is a summary of other quantification terms used in waterand wastewater programs.Minimum LevelThe ML is a quantification term defined by the USEP
45、A as:The concentration at which the entire analytical system must give a recognizablesignal and acceptable calibration point. The ML is the concentration in a samplethat is equivalent to the concentration of the lowest calibration standard analyzedby a specific analytical procedure, assuming that al
46、l of the method-specifiedsample weights, volumes, and processing steps have been followed.1The ML concept and how it is calculated have evolved over time. Currently, MLsare usually either calculated as 3.18 times the MDL, or set equal to the lowest calibrationstandard. The factor of 3.18 is derived
47、from another quantification term, the LOQ (seedescription later in this section).1 National Guidance for the Permitting, Monitoring, and Enforcement of Water Quality-Based Effluent Limitations Set Below Analytical Detection/Quantitation Levels, Draft,U.S. Environmental Protection Agency, Washington,
48、 DC, March 22, 1994.6Interim Minimum LevelInterim minimum level (IML) is a term created by the USEPA to describe MLsthat are based on 3.18 times the MDL, to distinguish them from MLs that have beenpromulgated.Practical Quantitation LevelThe PQL is a quantitation term originally developed by the USEP
49、A for itsdrinking water program. The USEPA defined the PQL as:The lowest level that can be reliably achieved within specified limits of precisionand accuracy during routine laboratory operating conditions50 FR 46906The PQL is intended to account for interlaboratory variability and matrix effects onquantitation. PQLs may be based on USEPA laboratory performance evaluation (PE)studies, choosing a level at which a majority of the laboratories can obtain results withina given rangefor example, 80% of the laboratories fall within 40% of the true value.In prac
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