UCMR 3

Laboratory Approval 

Requirements and

Information Document

Version 2.0

January 2012

Technical Support Center 

Standards and Risk Management Division 

Office of Ground Water and Drinking Water 

U.S. Environmental Protection Agency 

Cincinnati, OH 45268 

Laboratory Manager: ________________________________ 

This signature affirms that the Laboratory Manager

and staff anticipated to participate in UCMR 3 have read the

UCMR 3 Laboratory Approval Requirements and Information Document. 
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Office of Water (4607 M)

EPA 815-R-11-003 

January 2012 

http://water.epa.gov/drink/
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Foreword

The Revisions to the Unregulated Contaminant Monitoring Rule (UCMR 3) for Public Water 

Systems [40 CFR Part 141, National Primary Drinking Water Regulations] require public water 

systems (PWSs) to collect specific data and information during a defined monitoring period. The 

rule also establishes requirements and specifications for the reporting of UCMR 3 data to the 

United States Environmental Protection Agency (EPA). This technical manual serves as a 

support document for laboratories interested in becoming EPA approved and maintaining their 

EPA approval to analyze samples collected at PWSs to meet the UCMR 3 requirements for 

chemical contaminants. 

The main objective of this UCMR 3 Laboratory Approval Requirements and Information 

Document (referred to as the UCMR 3 Lab Approval Manual) is to provide laboratories with 

detailed information on the UCMR 3 laboratory approval process. The document is intended to: 

• describe the laboratory approval process for chemical contaminants, 

• describe the procedures that EPA uses to assess a laboratory's ability to produce data of 

known and acceptable accuracy and precision, 

• describe the laboratory data quality control requirements for UCMR 3 chemical analyses,

and 

• further describe specific analytical procedures for UCMR 3. 

Laboratories will be required to follow this UCMR 3 Laboratory Approval Manual to process 

UCMR 3 samples collected at PWSs and maintain their status as an EPA approved UCMR 3

laboratory. 

This document was prepared by EPA’s Office of Ground Water and Drinking Water (OGWDW), 

Standards and Risk Management Division (SRMD), Technical Support Center (TSC), 

Cincinnati, Ohio. Additional information on the UCMR 3 program can be found at the UCMR 3

website, 

http://water.epa.gov/lawsregs/rulesregs/sdwa/ucmr/ucmr3/index.cfm
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Disclaimers 

1. Mention of trade names or commercial products does not constitute endorsement or 

recommendation for use. 

2. This document describes the provisions of the UCMR 3 program, the approved analytical 

methods for UCMR 3 chemical contaminants, and EPA regulations that establish legally 

binding requirements. However, this document does not substitute for those provisions or 

regulations.

3. Laboratory approval to perform UCMR 3 analyses will only apply during UCMR 3

monitoring. If new drinking water regulations are promulgated using similar analyses 

and/or the same methods, laboratories will then be required to be certified through the 

process appropriate to their primacy agent (i.e., their State and/or EPA Region). 

4. The UCMR 3 approval process is not related to the laboratory certification process for 

conducting compliance monitoring under other National Primary Drinking Water 

Regulations (NPDWRs). A laboratory’s approval for UCMR 3 analyses has no impact on 

their certification to perform compliance monitoring under other NPDWRs. 
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Contents

Foreword ........................................................................................................................................ 3

Disclaimers..................................................................................................................................... 4

Acronyms and Abbreviations ...................................................................................................... 7

Section 1. Introduction ............................................................................................................... 10

1.1 Background on the Unregulated Contaminant Monitoring Rule ................................ 10

1.2 Ensuring Data Quality for UCMR 3 ........................................................................... 10

Section 2. UCMR 3 Laboratory Approval Process .................................................................. 11

2.1 Registration for the UCMR 3 Laboratory Approval Program .................................... 11

2.2 UCMR 3 LAP Applications ........................................................................................ 11

2.3 UCMR 3 Proficiency Testing ..................................................................................... 12

Section 3. Laboratory Quality Management Plan and UCMR 3 Quality Assurance 

Project Plan ........................................................................................................................... 14

3.1 Laboratory Quality Management Plan ........................................................................ 14

3.2 UCMR 3 Quality Assurance Project Plan ................................................................... 16

Section 4. Approved Methods for UCMR 3 Monitoring ......................................................... 17

Section 5. Initial Demonstration of a Laboratory's Ability to Perform 

UCMR 3 Analyses ................................................................................................................. 22

Section 6. Minimum Reporting Levels ...................................................................................... 24

Section 7. Quality Control Requirements ................................................................................. 26

7.1 Initial Calibration of Analytical Instruments .............................................................. 27

7.2 Continuing Calibration Checks ................................................................................... 29

7.3 Surrogate Requirements and Criteria .......................................................................... 31

7.4 Internal Standard Requirements and Criteria .............................................................. 33

7.5 Laboratory Reagent Blank .......................................................................................... 35

7.6 Laboratory Fortified Blank ......................................................................................... 36

7.7 Quality Control Sample (QCS) ................................................................................... 37

7.8 Laboratory Fortified Sample Matrix (Spiked Sample) ............................................... 38

7.9 Analytical Sequence.................................................................................................... 39

Section 8. Sample Handling Requirements .............................................................................. 41

8.1 Field Blanks ................................................................................................................ 41

8.2 Sample Transport and Storage .................................................................................... 42

8.3 Sample Preservation.................................................................................................... 43
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8.4 Maximum Holding Times ........................................................................................... 44

8.5 Laboratory Errors or Sampling Deviations ................................................................. 45

Section 9. References .................................................................................................................. 46

Appendix A. Requirements for UCMR 3 Metal Analysis ....................................................... 48

Appendix B. Lowest Concentration Minimum Reporting Level (LCMRL) Data used to 

Determine UCMR 3 Minimum Reporting Levels (MRLs) .............................................. 49

Tables

Table 1. UCMR 3 Chemical Analytes and Methods .................................................................... 20

List 1: Assessment Monitoring ......................................................................................... 20

List 2: Screening Survey ................................................................................................... 21

Table 2. IDC Requirements .......................................................................................................... 23

Table 3. Initial Calibration Acceptance Criteria ........................................................................... 29

Table 4. CCC Acceptance Criteria ................................................................................................ 31

Table 5. Surrogate Standards, Concentrations and Criteria .......................................................... 32

Table 6. Internal Standards, Concentrations and Criteria ............................................................. 34

Table 7. Laboratory Reagent Blank Criteria ................................................................................. 36

Table 8. Laboratory Fortified Blank Acceptance Criteria ............................................................ 37

Table 9. QCS Frequency Requirements ........................................................................................ 38

Table 10. Field Blanks .................................................................................................................. 42

Table 11. Requirements for Sample and Extract Storage Temperatures ...................................... 43

Table 12. Sample Preservatives and Dechlorinating Agents (Concentration in Sample) and 

Acceptance Criteria ................................................................................................................. 44

Table 13. Maximum Holding Times for Samples and Extracts .................................................... 45

Table 14. Determination of Metals for UCMR 3 based on EPA Method 200.8 Rev. 5.4 ............ 48

Examples

Example 1. Calculation of the PIR Limits .................................................................................... 25

Example 2. Valid Analysis Sequence for Method 537 ................................................................. 40
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Acronyms and Abbreviations

13C-PFDA Perfluoro-n-[1,2-13C2]decanoic acid

13C-PFHxA Perfluoro-n-[1,2-13C2]hexanoic acid 

13C-PFOA Perfluoro-[1,2-13C2]octanoic acid

13C-PFOS Sodium perfluoro-1-[1,2,3,4-13C4]octanesulfonate

APHA American Public Health Association 

ASTM ASTM International

AWWA American Water Works Association 

Bi Bismuth

BFB 4-bromofluorobenzene

C18 Octadecyl-functionalized silica gel

CAS Chemical Abstract Service

CCC Continuing calibration check

CFR Code of Federal Regulations

Co Cobalt

d3-NMeFOSAA N-deuteriomethylperfluoro-1-octanesulfonamidoacetic acid 

d5-NEtFOSAA N-deuterioethylperfluoro-1-octanesulfonamidoacetic acid

DCA Dichloroacetate

EPA United States Environmental Protection Agency

Estriol-d2 16α-hydroxyestradiol-d2

GC/MS Gas chromatography/mass spectrometry

HRPIR Half range for the prediction interval of results

IC Ion chromatography

ICP/MS Inductively coupled plasma - mass spectrometer 

ID Identification

IDA Initial demonstration of accuracy

IDC Initial demonstration of capability

IDP Initial demonstration of precision

In Indium

L Liter

LAP Laboratory Approval Program

LCMRL Lowest concentration minimum reporting level

LC-ESI-MS/MS Liquid chromatography electrospray ionization tandem mass spectrometry

LC/MS/MS Liquid chromatography/tandem mass spectrometry

LFB Laboratory fortified blank

LFSM Laboratory fortified sample matrix

LFSMD Laboratory fortified sample matrix duplicate

LRB Laboratory reagent blank

mL Milliliter

Mo Molybdenum
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Acronyms and Abbreviations

MRL Minimum reporting level

m/z Mass to charge ratio

NA Not applicable 

NERL National Exposure Research Laboratory

OEI Office of Environmental Information

OGWDW Office of Ground Water and Drinking Water

ORD Office of Research and Development

PFBS Perfluorobutanesulfonic acid

PFHpA Perfluoroheptanoic acid

PFHxS Perfluorohexanesulfonic acid

PFNA Perfluorononanoic acid

PFOA Perfluorooctanic acid

PFOS Perfluorooctanesulfonic acid

PIR Prediction interval of the result

PIRlower Lower PIR limit

PIRupper Upper PIR limit

PT Proficiency testing

PWS Public water system

QA Quality assurance

QAPP Quality Assurance Project Plan

QC Quality control

QCS Quality control sample

QMP Quality Management Plan

RSD Relative standard deviation

RPD Relative percent difference

s Standard deviation

Sc Scandium

SDVB Polystyrenedivinylbenzene

SDWA Safe Drinking Water Act

SDWARS Safe Drinking Water Accession and Review System

SIM Selective ion monitoring 

SM Standard Methods for the Examination of Water and Wastewater

SOP Standard operating procedure

SPE Solid phase extraction

Sr Strontium

Tb Terbium

TSC Technical Support Center

THF-d8 Tetrahydrofuran-d8

UCMR Unregulated Contaminant Monitoring Rule
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Acronyms and Abbreviations

UCMR 1 First Unregulated Contaminant Monitoring Rule

UCMR 2 Second Unregulated Contaminant Monitoring Rule

UCMR 3 Third Unregulated Contaminant Monitoring Rule

(v:v) Volume to volume

V Vanadium 

VOC Volatile organic contaminant

WEF Water Environment Federation 

 ̄x Mean

μL Microliter
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Section 1. Introduction

1.1 Background on the Unregulated Contaminant Monitoring Rule

The Safe Drinking Water Act (SDWA), as amended in 1996, requires EPA to establish criteria 

for a program to monitor unregulated contaminants and to publish a list of contaminants to be 

monitored every five years. In fulfillment of this requirement, EPA published the contaminant 

lists for the first and second UCMRs (i.e., UCMR 1 and UCMR 2, respectively) in the Federal 

Register in September 1999 and January 2007. The UCMR program uses a three-tiered approach 

for monitoring contaminants based on the availability of analytical methods. UCMR 3

monitoring will occur from January 2013 through December 2015. 

EPA identified 28 chemical contaminants and two viruses for UCMR 3. Monitoring for the 

chemical contaminants is supported by eleven analytical methods and addressed within this 

manual. Virus analyses will be conducted by laboratories under contract with EPA and are not 

addressed in this document. 

1.2 Ensuring Data Quality for UCMR 3

Data reported under UCMR 3 must meet specific precision and accuracy targets to achieve the 

objectives of the program. During UCMR 3 development, EPA established criteria to ensure that 

data generated during the monitoring period are of high quality. Maintaining data comparability 

among laboratories is essential, and will allow the data to be used in statistical analyses to 

reliably predict the national occurrence of the chemical contaminants in drinking water. EPA

ensures the integrity of the data by: 1) defining and maintaining strict requirements for sample 

collection, sample handling, processing and analysis, and data reporting, and 2) assisting the 

drinking water industry in identifying qualified laboratories that can accurately and reliably 

perform the analyses required by UCMR 3. 

The laboratory approval process described in this document ensures that analytical data 

generated for the UCMR are of adequate quality. EPA used a similar laboratory approval 

approach in UCMR 1 and UCMR 2 and believes this process is effective in yielding high quality 

data. An overview of the Laboratory Approval Program (LAP) and its requirements for UCMR 3

is presented in this UCMR 3 Lab Approval Manual, including: 

• a description of the UCMR 3 laboratory approval process; 

• a discussion of the required quality assurance (QA) documentation that must be prepared 

and followed at EPA-approved UCMR 3 laboratories;

• a summary of the UCMR 3 chemical contaminant analytical methods, minimum reporting 

levels (MRLs), and initial demonstration of capability (IDC) requirements; and 

• a summary of the laboratory data quality control (QC) requirements for UCMR 3 analyses. 

Laboratories must follow the procedures outlined in this document to obtain approval for the 

analysis of UCMR 3 samples.
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Section 2. UCMR 3 Laboratory Approval Process

Laboratories analyzing samples for UCMR 3 chemical contaminants must follow the process 

outlined in this section to obtain approval. Approval is by method and individual laboratory

location. A laboratory may apply for approval for any number of UCMR 3 methods. If a 

laboratory organization has multiple locations, each laboratory location must complete the 

process independently.

2.1 Registration for the UCMR 3 Laboratory Approval Program

Laboratories interested in UCMR 3 laboratory approval are to contact EPA as soon as possible. 

Laboratories must request UCMR 3 registration no later than August 1, 2012. Laboratories 

should send a letter of interest with contact information, including an e-mail address, to the 

following address: 

UCMR Laboratory Approval Coordinator 

U.S. Environmental Protection Agency 

Technical Support Center

26 West Martin Luther King Drive (MS 140) 

Cincinnati, OH 45268

or to the e-mail address: UCMR_Sampling_Coordinator@epa.gov

Upon receipt of correspondence from a laboratory indicating their interest in participating in the 

UCMR 3 LAP, EPA will e-mail UCMR 3 registration information to the laboratory. 

The laboratory must complete the UCMR 3 registration sheet, indicating the UCMR 3 chemistry

methods for which they are seeking approval, and return it to EPA at the above e-mail address. 

Laboratories will be asked to provide their EPA Lab ID code on the registration sheet. If a 

laboratory does not have an EPA Lab ID code, one will be assigned by EPA. Registration 

information must be received by EPA no later than September 1, 2012. Method specific 

applications must be returned to EPA by September 28, 2012. 

2.2 UCMR 3 LAP Applications 

EPA will forward the appropriate application packet to the laboratory based on the information 

provided on the registration sheet. The application packet will include a general application, and 

a method-specific application for each method selected on the registration sheet. 

To complete these applications, laboratories are required to:

• Document drinking water certification by a state or regional Certification Authority for the 

analysis of samples using gas chromatography, liquid chromatography, ion 

chromatography, and/or inductively coupled plasma mass spectrometry methods, as 

indicated in the applications; 

• Provide personnel and QA information, including a copy of the Table of Contents from the 

laboratory’s Quality Management Plan (QMP; see Section 3.1); 

• Provide information regarding analytical equipment and sample handling procedures; 
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• For each method for which the laboratory is seeking approval, submit data from: 1) an IDC 

study (see Section 5); 2) analysis of laboratory reagent blank (LRB) samples (see Section 

7.5); and 3) analysis of a set of laboratory fortified sample matrix (LFSM), LFSM duplicate 

(LFSMD), and the corresponding unfortified drinking water sample (see Section 7.8). Data 

submitted must include labeled chromatographic and/or spectrometric traces, quantitation 

reports, surrogate recovery results and internal standard recovery results; and

• Document that they will post UCMR 3 results to the EPA’s electronic data reporting 

system, the Safe Drinking Water Accession and Review System (SDWARS). Laboratories 

must report field sample results and associated QC data, as required by SDWARS, within 

120 days from the sample collection date. Failure to post data to SDWARS may result in 

EPA revoking the laboratory’s approval status. Once approval is revoked, the laboratory 

cannot be reapproved during the UCMR 3 monitoring period. 

 

Completed applications are to be returned as soon as possible. EPA will acknowledge receipt of 

application materials in correspondence to the laboratory. 

EPA will review the submitted application materials. If all requested information is present and 

acceptable, EPA will notify the laboratory that they are eligible to participate in a UCMR 3

proficiency testing (PT) study. If deficiencies are identified in the application materials, EPA 

will identify the area(s) of deficiency and necessary corrective actions to be taken in a report to 

the laboratory. Laboratories who receive a deficiency report will have the opportunity to make 

corrective actions and submit new application information. EPA anticipates the UCMR 3 LAP 

application period will close with the application submission deadline for the last UCMR 3 PT

study, September 28, 2012. 

2.3 UCMR 3 Proficiency Testing 

EPA conducted at least two PT studies prior to publication of the UCMR 3 final rule and intends 

to offer a minimum of three PT studies prior to closing the Laboratory Approval Program. Each 

laboratory must pass one PT study for each method for which they are seeking approval. When 

the laboratory’s application for a specific method is reviewed and determined to meet the UCMR 

3 method criteria, that laboratory can participate in EPA’s UCMR 3 PT study for that method. 

Participation in a PT study is method-specific; i.e., a laboratory is not required to concurrently 

participate in a PT study for all methods for which they are seeking approval. 

EPA will send a method-specific PT ampule to laboratories, with instructions and a cover letter 

specifying a due date for reporting results to EPA. The laboratory will always have a minimum 

of two weeks to perform the analysis. Laboratories should not assume that all UCMR 3 analytes 

for a method will be present in a PT ampule for that method. Laboratories that do not pass the PT 

study for a given method can participate in the next PT study for that method, if one is 

scheduled. However, laboratories that have passed a PT study for a given method will not 

receive additional PT samples for that method during subsequent UCMR 3 PT studies.

Upon successful participation in a PT study for a specific method, the laboratory will be notified 

in writing that it has met the initial approval criteria for each method. 

Laboratories that passed a PT study prior to publication of the UCMR 3 final rule were granted 

“Pending Approval” for UCMR 3, contingent upon: 1) changes applied to the final rule as a 

result of public comments to the proposed rule, and 2) resolution of any findings resulting in a 
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laboratory audit. Laboratories are not authorized to analyze UCMR 3 monitoring samples until 

they receive formal “Final Approval” in writing from EPA. EPA will not accept analytical 

results for UCMR 3 samples collected prior to the monitoring date specified in the final UCMR 

3. 
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Section 3. Laboratory Quality Management Plan and UCMR 3

Quality Assurance Project Plan

A Quality Management Plan (QMP) is a document that describes the general practices of an 

organization or program. The QMP may be viewed as the "umbrella" document under which 

individual projects are conducted. A Quality Assurance Project Plan (QAPP) documents details 

specific to an individual project within the organization or program. 

3.1 Laboratory Quality Management Plan

Laboratories analyzing samples for UCMR 3 are required to adhere to defined QA/QC 

procedures. This ensures that analytical data generated for UCMR 3 are scientifically valid and 

are of known and acceptable precision and accuracy. Each laboratory must have a written 

description of its QA activities detailed in a QMP, which describes the QA management of dayto-day routine operations. A QMP documents how an organization will plan, implement, and 

assess the effectiveness of its QA and QC operations. Specifically, it describes how an 

organization structures their quality system, including: quality policies and procedures; areas of 

application; and roles, responsibilities, and authorities. The QMP must be kept current during the 

time the laboratory is performing UCMR 3 measurements. Laboratories are required to submit a 

copy of the Table of Contents from their QMP to EPA as part of the UCMR 3 LAP (see Section 

2.2). 

Certain sections of the laboratory QMP can reference existing documented procedures, such as 

the laboratory's standard operating procedures (SOPs), EPA analytical methods, or other 

literature (e.g., Standard Methods for the Examination of Water and Wastewater). More 

information regarding laboratory QMPs can be found in EPA Requirements for Quality 

Management Plans (QA/R-2, see Section 9 References).

At a minimum, the laboratory’s QMP will address the following topics: 

1. Laboratory organization and responsibility 

• The laboratory’s organizational chart showing lines of authority, including QA 

Managers; 

• A list of key individuals responsible for producing valid measurements and conducting 

routine assessments of QC procedures and measurements; 

• Identification of the person(s) responsible for internal audits/reviews of the 

implementation of the QMP and its requirements; and 

• A description of laboratory training to keep personnel current on regulations, methods, 

etc.

2. Field sampling

• Personnel responsible for collecting samples; 

• Procedures for sample collection, preservation, containment, holding times, and 

transport to the laboratory; 
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3. Laboratory sample handling procedures

• Procedures for sample receipt, including criteria for the rejection of samples that do not 

meet shipping, holding time and/or preservation requirements; 

• Bench sheets used upon sample receipt, during extraction/digestion of samples, and 

during analysis of samples, extracts or digestates; 

• Storage requirements for samples, extracts, and digestates, including criteria for 

temperature and holding times; and 

• Sample tracking used to maintain the integrity of all samples from receipt by the 

laboratory through analysis and reporting to disposal. 

4. Chemical, reagent and standard control procedures

• Procedures for preparation, labeling, documentation and storage of reagents, chemicals, 

calibration standards, surrogate standards, internal standards, etc.; and

• Frequency of initial calibration, continuing calibration checks (CCCs), and validation 

of calibrations. 

5. Analytical procedures

• Reference methods and corresponding SOP numbers/names used for each type of 

analysis; 

• Location of SOPs; 

• Frequency of SOP review; 

• Analytical instrument identification/labeling; and 

• Identification of which analytical instruments are used for each type of analysis. 

6. Data reduction, verification, validation and reporting 

• Process for converting raw data to reportable concentrations; 

• Process for ensuring the accuracy of data transcription and calculations; 

• Process for validating data; 

• Process and format for reporting results to clients; and

• Procedure used for data corrections. 

7. QC Procedures

• Types and frequency of QC sample analysis; 

• MRL verification procedures, criteria and frequency; 

• Use and criteria for internal and surrogate standards; and 

• Procedures for IDCs, and preparation of control charts. 
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8. Preventive maintenance

• Equipment manual location and availability; 

• Spare parts inventory; and

• Schedule and procedures for, and documentation of, preventative maintenance. 

9. Corrective action

• Response to obtaining unacceptable results from the analysis of PT samples or internal 

QC checks; 

• Identification of the person(s) responsible for determining that corrective action is necessary, and 

ensuring that it is completed; and

• Procedure for documenting actions taken and their effectiveness. 

10. Record Keeping

• Procedure for maintaining records, including duration and location; and 

• Procedure for backing-up databases/electronic files.

The laboratory QMP is to be concise but responsive to the above-listed items. The QMP 

maintains and improves data dependability and quality. 

3.2 UCMR 3 Quality Assurance Project Plan

All laboratories seeking approval to perform chemical analyses for UCMR 3 are required to 

prepare a QAPP specific to UCMR 3. The UCMR 3 QAPP supplements the laboratory QMP by 

documenting the specific changes in sample handling, analytical methods, QC, and data 

reporting that the laboratory makes to address the UCMR 3 requirements. Laboratories must 

make this document available to EPA for review, if requested. 

More information regarding the preparation of a QAPP can be found in EPA Requirements for 

Quality Assurance Project Plans (QA/R-5, see Section 9 References).
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Section 4. Approved Methods for UCMR 3 Monitoring

Laboratories must use the methods specified in CFR §141.40(a)(3) Table 1 to perform UCMR 

analyses during the 3-year monitoring period. UCMR 3 methods are summarized below and 

listed in Table 1 of this document. UCMR 3 laboratories must follow all analytical and QC 

procedures outlined in the methods and in this document (see Section 7). Analyses may be 

conducted only by laboratories formally approved by EPA for UCMR 3. Sampling and analysis 

for UCMR 3 shall not begin prior to the monitoring period specified in the final rule.

EPA Method 200.8 Rev. 5.4, ASTM Method D5673-10, or SM 3125 

Determination of Trace Elements in Waters and Wastes by Inductively Coupled Plasma – Mass 

Spectrometry 

Total recoverable analytes in a 100-milliliter (mL) water sample are solubilized by gentle heating 

(i.e., digestion) with nitric acid (do not use hydrochloric acid) on a hot plate (or hot block) that 

is set no higher than 85°C. (Note: For UCMR 3, all samples for metals analysis by ICP/MS

must be digested, regardless of sample turbidity and method.) Microwave digestion, with a 

reduced sample volume, is allowed only if all QC requirements are met. When the sample 

volume has been evaporated to approximately 20 mL (this should take about two hours), it is 

refluxed for an additional 30 minutes and then removed from heat and allowed to cool. The 

cooled sample is quantitatively transferred to a 50-mL Class A glass flask or cylinder. An aliquot 

of a solution containing internal standards indium (In), scandium (Sc), and terbium (Tb) is added 

and the solution is diluted to volume. The sample is then introduced by pneumatic nebulization 

into an argon-based, high-temperature radiofrequency plasma where energy transfer processes 

cause desolvation, atomization and ionization. The ions are extracted from the plasma through a 

differentially pumped vacuum interface and separated on the basis of their mass-to-charge ratio 

(m/z) by a quadrupole mass spectrometer. The ions are then detected by an electron multiplier or 

Faraday detector, and the ion information is processed by a computer-based data handling 

system. See Appendix A of this manual for important details regarding specific UCMR 3

analytical requirements. 

EPA Method 218.7 

Determination of Hexavalent Chromium in Drinking Water by Ion Chromatography With Postcolumn Derivatization and UV-visible Spectroscopic Detection

Ammonium sulfate is added to the sample, along with a buffer, to raise sample pH to a value 

greater than eight. Free chlorine, which may be present in drinking water, reacts with 

ammonium ions to form chloramines, effectively inhibiting the chlorine-mediated formation of 

Chromium-6 from Chromium-3 during sample storage. Above pH 8, hexavalent chromium 

exists as the stable and soluble chromate anion, CrO4

-2. A measured volume of the sample, 

usually 1 mL, is introduced into an ion chromatograph. A guard column removes organic 

compounds from the sample and CrO4

-2 is separated from other matrix components on an anion 

exchange column. Derivatization of the chromate anion with 1,5-diphenylcarbazide in a postcolumn reactor is followed by detection of the resulting colored complex at a wavelength of 530 

nm. Chromium-6 is qualitatively identified via retention time, and the concentration of CrO4

-2 in 

the sample is calculated using the integrated peak area and the external standard technique. 
Page 18 of 50

Results are reported in units of μg/L of Chromium-6 (atomic weight 51.996). 

EPA Method 300.1, ASTM Method D6581-08, or SM 4110D 

Determination of Inorganic Anions in Drinking Water by Ion Chromatography 

A 10-mL aliquot of sample is fortified with the surrogate standard dichloroacetate (DCA) and 

filtered through a 0.45 micron particulate filter using a syringe filtration apparatus. Fifty 

microliters (μL) of the filtrate are injected into an ion chromatograph fitted with: an anionexchange guard column, an anion-exchange analytical column, a background conductivity 

suppressor device, a conductivity cell detector and a data acquisition system. The anions in the 

sample are separated on the basis of their relative affinities for the low-capacity, strongly basic 

anion exchange columns. The separated anions are directed through the suppressor device where 

they are converted to their highly conductive acid forms, while the conductivity of the eluent is 

greatly decreased. The acid forms of the anions are measured by conductivity and identified on 

the basis of retention time as compared to calibration standards analyzed under identical 

conditions. The concentration of each analyte in the sample is calculated by comparing the area 

of its peak to a standard curve developed from the analysis of the calibration standards. 

EPA Method 522

Determination of 1,4-Dioxane by Solid Phase Extraction (SPE) and Gas Chromatography/Mass 

Spectrometry (GC/MS) with Selected Ion Monitoring (SIM) 

A water sample is spiked with the isotopically labeled surrogate standard 1,4-dioxane-d8. The 

sample is extracted using one of two SPE options. In option 1, a 500-mL sample is passed 

through a method-specific, pre-packed cartridge composed of a 6 mL polypropylene tube 

containing 2 grams of coconut charcoal. These cartridges are commercially available from 

Restek Corp. or United Chemical Technologies Inc. but equivalent brands with a particle size of 

80-120 mesh (approximately 150 μm) meeting all QC criteria in the method may be used. In 

option 2, a 100-mL sample is extracted on a Waters AC-2 Sep-Pak or Supelco ENVI-Carb Plus 

cartridge or equivalent. In both options, the analytes are eluted from the solid phase with 

dichloromethane, and the extract is concentrated and fortified with the internal standard 

tetrahydrofuran-d8 (THF-d8). The final extract is dried with anhydrous sodium sulfate and 

injected using splitless injection onto a high-resolution fused silica capillary gas chromatography 

column interfaced to a mass spectrometer operated in the SIM mode. Sample extract components 

are separated by the column and identified by comparing the acquired mass spectra and retention 

times to reference spectra and retention times for calibration standards acquired under identical 

GC/MS conditions. Analyte and surrogate standard concentrations are calculated using the multipoint calibration curve established in the method. 

EPA Method 524.3 

Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas 

Chromatography/Mass Spectrometry 

A 5-mL aliquot of sample is transferred to a glass sparging vessel along with internal standards 

1,4-difluorobenzene, chlorobenzene-d5, and 1,4-dichlorobenzene-d4 and surrogate standards 

methyl-t-butyl-ether-d3, 4-bromofluorobenzene (BFB), and 1,2-dichlorobenzene-d4. Volatile 
Page 19 of 50

organic contaminants (VOCs) are purged from the water using helium, and trapped on sorbent 

material. After drying, the trap is heated and backflushed with helium to transfer the VOCs 

directly into the gas chromatograph inlet. From the inlet, operated in split mode, analytes are 

transferred onto the capillary GC column where they are separated using a gas chromatograph 

operated in temperature programming mode. Analytes eluting from the GC column are directed 

into a mass spectrometer for detection and quantitation. The method analytes are identified by 

comparing the acquired mass spectra and retention times to reference spectra and retention times 

for calibration standards acquired under identical GC/MS conditions. The concentration of each 

analyte is calculated using the internal standard technique and response curves obtained using 

procedural calibration. 

EPA Method 537

Determination of Selected Perfluorinated Alkyl Acids in Drinking Water by Solid Phase 

Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS) 

A 250-mL water sample is fortified with surrogates perfluoro-n-[1,2-13C2]hexanoic acid 

(

13C-PFHxA) and perfluoro-n-[1,2-13C2]decanoic acid (13C-PFDA. Method analytes and 

surrogates are extracted by passing the sample through an SPE cartridge containing 

polystyrenedivinylbenzene (SDVB). The analytes are eluted from the solid phase with a small 

volume of methanol. The extract is concentrated to dryness with nitrogen in a heated water bath. 

Internal standards perfluoro-[1,2-13C2]octanoic acid (13C-PFOA) and sodium perfluoro-1-

[1,2,3,4-13C4]octanesulfonate (13C-PFOS) are added, and the extract is adjusted to a 1mL volume 

with 96:4% (v:v) methanol:water. The analytes are chromatographically separated by injecting a 

10-μL aliquot onto a C18 column in a liquid chromatograph system that is interfaced to tandem 

mass spectrometers. After elution from the column, method analytes are identified by comparing 

the acquired mass spectra and retention times to reference spectra and retention times for 

calibration standards acquired under identical LC/MS/MS conditions. The concentration of each 

analyte is calculated using the internal standard technique. 

EPA Method 539

Determination of Hormones in Drinking Water by Solid Phase Extraction (SPE) and Liquid 

Chromatography Electrospray Ionization Tandem Mass Spectrometry (LC-ESI-MS/MS) 

A 1-liter (L) water sample is fortified with surrogate standards ethynylestradiol-d4 and bisphenol 

A-d16. Method analytes and surrogates are extracted by passing the sample through an SPE disk 

containing C18 functional groups. The analytes are eluted from the solid phase with a small 

volume of methanol. The extract is concentrated to dryness with nitrogen in a heated water bath. 

A solution containing internal standards 16α-hydroxyestradiol-d2 (Estriol-d2), 13C6-Estradiol, 

13C2-ethynylestradiol, and testosterone-d3 is added, and the extract is adjusted to a 1-mL volume 

with 50:50% (v:v) methanol:water. The analytes are chromatographically separated by injecting 

an aliquot onto a C18 column in a liquid chromatography system that is interfaced to tandem 

mass spectrometers. After elution from the column, method analytes are identified by comparing 

the acquired mass spectra and retention times to reference spectra and retention times for 

calibration standards acquired under identical LC-ESI-MS/MS conditions. The concentration of 

each analyte is calculated using the internal standard technique. 
Page 20 of 50

Table 1. UCMR 3 Chemical Analytes and Methods

List 1: Assessment Monitoring

1-Analytical 

Method 2-Contaminant

3-CAS Registry 

Number

4-Suggested 

Quant Ions 

Parent/Daughter

(m/z)

5-MRL

(μg/L)

EPA 200.8, 

ASTM D5673-10, or

SM 3125

Trace Element 

Metals by ICP/MS*

chromium (Cr) 7440-47-3 52 0.2

cobalt (Co) 7440-48-4 59 1.0

molybdenum (Mo) 7439-98-7 98 1.0

strontium (Sr) 7440-24-6 88 0.3

vanadium (V) 7440-62-2 51 0.2

EPA 218.7

Hexavalent 

chromium by IC

chromium-6 (measured 

as CrO4

-2) 

13907-45-4 Not applicable 0.03 

EPA 300.1, 

ASTM D6581-08, or

SM 4110D

Inorganic anions by 

IC

chlorate 14866-68-3 Not applicable 20

EPA 522

1,4-Dioxane by 

GC/MS

1,4-dioxane 123-91-1 88 0.07

EPA 524.3

VOCs by GC/MS

1,1-dichloroethane 75-34-3 63 0.03

1,2,3-trichloropropane 96-18-4 110 0.03

1,3-butadiene 106-99-0 54 0.1

bromochloromethane 

(halon 1011) 74-97-5 128 0.06

chlorodifluoromethane 

(HCFC-22) 75-45-6 51 0.08

chloromethane 74-87-3 50 0.2

bromomethane 74-83-9 94 0.2
Page 21 of 50

Table 1. UCMR 3 Chemical Analytes and Methods

List 1: Assessment Monitoring

1-Analytical 

Method 2-Contaminant

3-CAS Registry 

Number

4-Suggested 

Quant Ions 

Parent/Daughter

(m/z)

5-MRL

(μg/L)

EPA 537

Perfluorinated 

compounds by 

LC/MS/MS

perfluorooctanesulfonic 

acid (PFOS) 1763-23-1 499/80 0.04

perfluorooctanoic acid 

(PFOA) 335-67-1 413/369 0.02

perfluorohexanesulfonic 

acid (PFHxS) 355-46-4 399/80 0.03

perfluoroheptanoic acid 

(PFHpA) 375-85-9 363/319 0.01

perfluorononanoic acid 

(PFNA) 375-95-1 463/419 0.02

perfluorobutanesulfonic 

acid (PFBS) 375-73-5 299/80 0.09

List 2: Screening Survey

EPA 539

Hormones by 

LC/MS/MS

17α-ethynylestradiol 57-63-6 295.1/144.7 0.0009

17β-estradiol 50-28-2 271.2/144.7 0.0004

equilin 474-86-2 267.1/142.7 0.004

estriol 50-27-1 287/144.7 0.0008

estrone 53-16-7 268.9/144.7 0.002

testosterone 58-22-0 289.1/96.8 0.0001

4-androstene-3,17-dione 63-05-8 287.1/96.6 0.0003

* See Appendix A of this manual for specific requirements. 

Explanation of Table 1 column headings: 

1 Analytical Method: Method number and condensed method name for methods that must be used to 

analyze samples for the applicable UCMR 3 contaminant(s). Reference information for the methods is 

listed in Section 9 References.

2 Contaminant: The name of the contaminant and abbreviation (if applicable) to be analyzed.

3 CAS Registry Number: A unique numerical identifier for the chemical, assigned by Chemical Abstract 

Service (CAS), a division of the American Chemical Society.

4 Suggested Quant Ions: Acceptable mass to charge ion ratio to be used for the quantitation of the analyte, 

for methods using MS. For MS/MS methods, the precursor/product ions are listed. For the metals methods 

(EPA 200.8, ASTM D5673-10, SM 3125), all isotopes listed in Appendix A must be monitored. 

5 Minimum Reporting Level: The lowest concentration of each analyte that must be reported to EPA.
Page 22 of 50

Section 5. Initial Demonstration of a Laboratory's Ability to 

Perform UCMR 3 Analyses

Each laboratory seeking approval for UCMR 3 methods must complete an initial demonstration 

of capability study for each method. EPA recognizes that a laboratory may use multiple 

instruments and analysts to perform analysis. If more than one analyst performs UCMR 3

analyses, EPA recommends that each analyst perform an IDC study before they analyze UCMR 

3 samples. Similarly, an IDC study is to be performed using each instrument that will be used to 

analyze UCMR 3 samples. This will ensure that each operator and each instrument maintains the

minimum quality standards. Data from each of these tests are to be maintained at the laboratory 

for EPA’s review in the event that the Agency wishes to conduct an audit before or during the 

UCMR 3 monitoring and data analysis period. 

IDC study data must be submitted as part of the laboratory approval application package. One set 

of IDC study data, representative of typical performance of the operators and instruments used 

for the applicable method, is to be included in the application package for each method. The 

UCMR 3 method-specific application sheets provide the format for reporting these data. 

EPA recommends that the laboratory verify the instrument calibration and sensitivity prior to 

performing the IDC study. The calibration curve must encompass the MRL concentration.

The IDC study involves demonstration of: 1) low system background, 2) precision, 3) accuracy, 

and 4) the laboratory’s ability to achieve the MRLs, as follows: 

1. Initial Demonstration of Low System Background – Analyze an LRB to verify that 

none of the analytes of interest are found above 1⁄3 to 1⁄2 the MRL, depending on the 

method used (Table 2).

 

2. Initial Demonstration of Precision (IDP) – Analyze 4 to 7 laboratory fortified blank 

(LFB) samples, as specified in the method, consisting of reagent water fortified at the 

"precision demonstration" concentration for each analyte of interest (i.e., 2xMRL to 

5xMRL). EPA recommends that these samples be fortified with a solution of method 

analytes obtained from a source external to the laboratory and different from the source 

of the calibration standards. The relative standard deviation (RSD) of the resulting 

analytical data set must meet the criterion specified in Table 2. 

3. Initial Demonstration of Accuracy (IDA) – Calculate the average recovery for the data 

set generated for the IDP (see preceding paragraph) using Equation 1. The average 

recovery must meet the criteria specified in Table 2. 

%100 1 ×÷

∑=

actual

n

i

i

LFB

n

LFB

Equation 1

4. MRL Verification – Laboratories must verify they can achieve the UCMR 3 MRL for 

each analyte according to the procedure outlined in Section 6. 
Page 23 of 50

Table 2. IDC Requirements

Analytical Method

LRB 

Requirement

Acceptable 

Precision

Acceptable 

Recovery 

(Accuracy) MRL Requirement

EPA 200.8,

ASTM D5673-10, 

SM 3125

Metals

No analyte 

>1⁄3MRL

RSD ≤ 10% 85 – 115% of true 

value 

Achieve laboratory

MRLs at or below 

values listed in Table 1 

for each of the 

UCMR 3 analytes

EPA 218.7

Chromium-6 RSD≤ 15% 85 – 115% of true 

value

EPA 300.1, ASTM 

D6581-08,

SM 4110D

Chlorate

RSD ≤ 15% 75 - 125% of true 

value

EPA 522

1,4-Dioxane RSD < 20% 80 – 120% of true 

value

EPA 524.3

VOCs 

No analyte 

>1⁄2MRL RSD ≤ 20% 80 – 120% of true value

EPA 537

Perfluorinated 

Compounds No analyte 

>1⁄3MRL

RSD < 20% 70 – 130% of true 

value

EPA 539

Hormones RSD ≤ 20% 70 – 130% of true 

value
Page 24 of 50

Section 6. Minimum Reporting Levels

The UCMR 3 analyte MRLs are statistically-based and were established by EPA using the 

lowest concentration minimum reporting levels (LCMRLs) determined by multiple laboratories 

according to the procedure detailed in Technical Basis for the Lowest Concentration Minimum 

Reporting Level (LCMRL) Calculator. The MRLs established for the UCMR 3 analytes are 

presented in Table 1. All laboratories performing analysis for the UCMR 3 must be able to 

measure the analyte concentrations at these levels with specified accuracy and precision. (See 

Section 7 for the criteria.) 

As part of the UCMR 3 LAP application process, laboratories must verify they can achieve the 

UCMR 3 MRLs for each analyte according to the procedure in CFR §141.40(a)(5)(iii) and 

outlined below. 

1. Fortify, process and analyze seven replicate LFBs. These LFBs must: contain all 

dechlorinating agents and preservatives specified by the method, contain each UCMR 3

analyte of interest at a concentration at or below the UCMR 3 MRL, and be processed 

through the entire method procedure (i.e., including extraction or digestion, where 

applicable). Dechlorinating agents and preservatives are listed in Table 12. 

2. Using the results from the analysis of the seven replicates, calculate the mean (x ̄ ) and 

standard deviation (s) for these replicates. Determine the half range for the prediction 

interval of results (HRPIR) using Equation 2: 

 HRPIR ×= s963.3 Equation 2

(Note: the factor 3.963 is specific only to use of seven replicates.) 

3. Confirm that the upper and lower limits for the prediction interval of the result (PIR = 

x ̄ + HRPIR) meet the upper and lower recovery limits.

The upper 

≤× %150%100 +

TrueValue

x HRPIR

PIR limit must be ≤150 percent recovery:

 Equation 3

The lower PIR limit must be ≥50 percent recovery:

 ≥× %50%100 x − HRPIR Equation 4 TrueValue

The MRL is validated if both the upper and lower PIR limits meet these criteria. 

These calculations are illustrated in Example 1.

 
Page 25 of 50

Example 1. Calculation of the PIR Limits (where the true value of the LFB concentration is 0.60μg/L)

LFB Results (x) 0.60 0.59 0.55 0.60 0.62 0.58 0.67

Step 1. Calculate the Mean ( x )

6014.0

7

1 21.4 = =→=→

∑= x x

n

LFB

x

n

i

i

Step 2. Calculate the Standard Deviation (s)

( )

0372.0

6

0083.0

1

1

2

=→ =→ −

−

=

∑= s s

n

LFB x

s

n

i

i

Step 3. Calculate the Half Range for the PIR (HRPIR)

HRPIR s963.3 HRPIR 0372.0963.3 HRPIR =→×=→×= 147.0

Step 4. Calculate the Upper PIR Limit (PIR upper)

%100 %7.124

60.0

147.06014.0 %100 →× = +

→× = + = upper upper

PIR

upper PIR PIR

TrueValue

x HR

PIR

→Passes (≤ 150%)

Step 5. Calculate the Lower PIR Limit (PIR lower)

%100 %7.75

60.0

147.06014.0 %100 →× = − →× = − = lower lower

PIR

lower PIR PIR

TrueValue

x HR

PIR

→ Passes ( ≥ 50%)
Page 26 of 50

Section 7. Quality Control Requirements

Laboratories applying for approval to analyze samples for UCMR 3 must use the analytical 

methods specified in Section 4 of this manual. Laboratories must follow the QC procedures 

outlined in the method(s) and in this manual. 

Field blank and sampling requirements are discussed in Section 8.1. Appendix A contains 

UCMR 3 specific requirements for the analysis of metals by ICP/MS, including required isotopes

to monitor, and correction equations to be used. 

An extraction or digestion batch is defined as all samples prepared/extracted/digested together 

by the same person during a work day. The same lots of reagents/solvents and internal 

standard/surrogate standard/analyte fortification solutions must be used for all samples included 

in a batch. For methods that use SPE techniques, it is preferable to use the same lot of pre-tested 

SPE medium. A maximum of 20 field samples (i.e., non-QC samples) can be included in an 

extraction or digestion batch. The extraction/digestion batch must be identified with a unique and 

traceable ID code or name.

In preparing samples for analysis, each digestion or extraction batch must include the following 

QC samples, at a minimum: 

• an LRB; 

• an LFB spiked at a concentration less than or equal to the MRL (LFB≤MRL); 

• and an LFSM/LFSMD pair spiked at a low or mid-level concentration (rotating 

concentrations from batch to batch). 

Results from the analysis of these QC samples are used to evaluate the validity of the sample 

processing procedures and techniques. Further explanation of the UCMR 3 requirements and 

criteria for these QC samples is presented in Sections 7.5 through 7.8. 

An analytical batch is defined as a group of field samples analyzed using the same instrument 

within a 24-hour period. For UCMR 3, analytical batches cannot include more than 20 field 

samples. QC samples are not counted in determining the number of samples in the analytical 

batch. The 24-hour period begins with the analysis of the first low-level CCC standard and ends 

with the analysis of the final mid- or high-level CCC standard. The analytical batch may or may 

not be comprised of field samples that were processed together in the same extraction or 

digestion batch. Ideally, however, field samples and corresponding QC samples in the same 

extraction or digestion batch should be analyzed in the same analytical batch. Each analytical 

batch must be identified with a unique and traceable ID code or name that is different than the 

extraction or digestion batch ID used in processing the samples. Field samples with QC failures 

may be re-analyzed immediately at the end of the analytical batch, but must be followed by a 

passing end CCC. If this is not possible, the re-analysis will need to be performed in a new 

analytical batch with a different ID and complete QA/QC analyses as appropriate to the method 

analytical batch. 

All UCMR 3 methods require fortification of field samples, QC samples, and calibration 

standards with surrogate and/or internal standards, with the exception of 218.7. The method-
Page 27 of 50

specific surrogate and internal standard requirements and criteria are summarized in Sections 7.3 

and 7.4, respectively. The surrogate and internal standards must be monitored during analysis of 

calibration standards (Section 7.1 and 7.2) as well as field and QC samples. 

Laboratory personnel involved in UCMR 3 must be very familiar with general and methodspecific procedures to: 

• prepare, label, and store standards and reagents; 

• prepare samples for analysis; 

• calibrate and operate the analytical instrumentation; 

• monitor system performance; 

• troubleshoot problems; 

• maintain thorough documentation of activities; and

• and review and report data. 

7.1 Initial Calibration of Analytical Instruments

Each method describes initial calibration procedures used to determine the concentrations of the 

method analytes. Some methods allow more than one option. The laboratory must select and 

follow one of the initial calibration procedures outlined in the approved method in order to meet 

the requirements of UCMR 3. For mass spectrometry methods, laboratories must meet the 

method-specific mass spectrometer tuning criteria prior to performing the initial calibration

procedure. 

If allowed by the method, different types of calibration (e.g., linear regression, quadratic fit, 

response factor calculation) and different fit types (e.g., forcing the curve through the origin, 

ignoring the origin, weighting factors) may be used for different analytes within a given method. 

However, the same calibration and fit type must be used for a given analyte for all analyses that 

are based on a given initial calibration. If modifications to the calibration or fit type are made, 

the instrument must be recalibrated.

The calibration curve for each UCMR 3 method must span the expected concentration range of 

the samples being analyzed, and must include a standard with a concentration less than or equal 

to the MRL. Some methods specify the minimum number and maximum range of standard 

concentrations to use for the calibration curve, and some do not. Laboratories must use a 

minimum of five calibration standards for all UCMR 3 methods. More than five standards 

must be used if specified by the method, such as EPA Methods 218.7 and 524.3. 

Calibration standards for Methods 218.7, 200.8, 300.1, and 524.3 require the addition of the 

same preservatives and dechlorinating agents as used in the field samples.

The recovery of UCMR 3 analytes, surrogate standards and internal standards must be monitored 

in the initial calibration standards using the calibration curve created from the initial calibration

data. Recoveries must meet the criteria defined in Table 3. If any surrogate or internal standard 

fails the criterion in a calibration standard, the data from that standard cannot be used in 

calculating the calibration curve. If all surrogate and internal standards pass the criteria, and a 

subset (but not all) of the analytes pass the recovery criterion, only the data for the passing 

analytes may be used in calculating the calibration curve. Standards with failed recoveries must 

be reanalyzed (and possibly re-prepared) until passing data are generated.
Page 28 of 50

Method 537 for perfluorinated compounds has some special considerations for calibration. 

During Method 537 development, standards containing linear and branched isomers were not 

available for all the perfluorinated compounds. However, Method 537 requires that all the 

perfluorinated analytes be purchased as technical grade standards or neat material, if 

commercially available, to account for the presence of various isomeric forms. Section 12.4 of 

Method 537 describes how to sum the areas of the isomers, but it only referred to the UCMR 3 

compound PFHxS and PFOS which could be purchased at the time as technical grade. If 

technical grade PFOA, PFNA, PFHpA and PFBS become commercially available, quantitation 

should be performed as described in Section 12.4 of the method. 

All UCMR 3 methods require verification of the initial calibration with a Quality Control Sample 

(QCS) prepared from a source different than that used to prepare the initial calibration standards. 

If a second source is not available, the QCS is to be prepared from a different lot of the source 

used to prepare the initial calibration standards. EPA recommends preparing the QCS at a 

concentration near the mid-point of the calibration curve. The QCS must contain internal 

standard(s) from the same source used in the initial calibration standards. The acceptance criteria 

for the QCS are the same as those for CCC standards with concentrations greater than the MRL 

(see Section 7.2), with the exception of the metals methods for which the criterion is ±10%. The 

initial calibration must be verified with a QCS each time a new analyte primary dilution standard 

is prepared, and at least quarterly. 

Laboratories must adhere to the holding time limitations for standard solutions, as well as other 

reagents and solutions, as specified in the individual methods. Expiration dates for prepared 

solutions cannot extend beyond the expiration date for the stock solution(s) from which they 

were prepared. If multiple stock solutions are used, the shortest expiration date applies. It is 

critical that laboratories closely monitor the expiration of calibration standards. 

Laboratories must adhere to the QC criteria limits and are NOT permitted to accept sample data 

when any QC parameter shows a high bias that exceeds the QC criteria limits. The only 

exception is limited to two methods (Method 522 and Method 537) and exclusively applies to 

limited allowance for high CCC recovery, as discussed further in Section 7.2. 
Page 29 of 50 

Table 3. Initial Calibration Acceptance Criteriaa

Analytical Method 

Recovery as % of true value 

Internal Standard Response 

Analytes 

>MRL 

Analytes 

≤MRL 

Surrogate 

Standard 

EPA 200.8, 

ASTM D5673-10, 

SM 3125 90 – 110% 50 – 150% NA 60 – 125% of the response in the calibration blank 

Metals 

EPA 218.7 

Chromium-6 85 – 115% 50 – 150% NA NA 

EPA 300.1, ASTM 

D6581-08, 

SM 4110D 

Chlorate 

85 – 115%b

 75 – 125%c 90 – 115% NA 

EPA 522 

1,4-Dioxane 80 – 120%d

 60 – 140%e

70 – 130% of the average IS 

EPA 524.3 response in all calibration standards

VOCs 70 – 130% 50 – 150%

 70 – 140% of the average IS 

EPA 537 response in all calibration standards 

Perfluorinated 70 – 130% 50 – 150%e

70 – 130% AND < 20% RPD among IS 

Compounds responses in the lowest and highest 

calibration standardsf

 

EPA 539 

Hormones 70 – 130% 50 – 150% 70 – 130% of the average IS 

response in all calibration standards

a

 For methods 218.7, 522, 524.3, 537, and 539 calibration standard responses must be entered into the 

calibration curve equation and the resultant calculated analyte concentrations must meet the accuracy criteria 

listed in the table 

b

 Applies to all chlorate methods when the true concentration of the analyte is >10xMRL. 

c

 Applies to all chlorate methods when the true concentration of the analyte is ≤10xMRL. d

 Applies to all Method 522 Initial calibration standards except the lowest concentration. 

e

 Applies only to the lowest Initial calibration concentration for Methods 522 and 537. 

f

 RPD between the high (H) and low (L) areas for each IS is calculated using the following equation: RPD ൌ

ሺୌି୐ሻ

ሺୌା୐ሻ/ଶ ൈ 100% 

7.2 Continuing Calibration Checks 

Once established, the calibration curve for a method must be verified each day that analysis is 

conducted. For all UCMR 3 methods, the initial calibration must be verified with a low-level 

(i.e., concentration ≤ MRL) CCC standard prior to the analysis of field (i.e., non-QC) 

samples. Even if the calibration curve is established on the day of analysis by analyzing the 

entire suite of initial calibration standards, laboratories must analyze a low-level CCC standard 

prior to field samples. The initial calibration must also be verified throughout each day by 

analyzing a CCC standard after every tenth field sample, and at the end of the analytical 

batch, alternating between the mid- and high-level concentrations on the calibration curve.
Page 30 of 50

CCC standards must meet the criteria defined in Table 4. The low-level CCC standard must meet 

the criteria before any samples are analyzed, and all samples must be bracketed by CCC 

standards that pass the criteria. Analytical results for a group of up to 10 samples are considered 

valid only if the CCC standards analyzed before and after the group meet the criteria.

If criteria are not met for a CCC standard, then the source of the problem must be identified and 

eliminated. This may require instrument maintenance and the generation of a new instrument 

calibration curve according to the method initial calibration procedures. All samples or extracts 

analyzed between the failing CCC standard and the last acceptable CCC standard must be 

reanalyzed for the failing analyte(s) after the problem is resolved. If the samples or extracts 

cannot be reanalyzed, then data for the problem analyte(s) are considered invalid for those 

samples and the data must not be reported. Laboratories reporting invalid data will be subject 

to revocation of UCMR 3 laboratory approval status. Once approval is revoked, the 

laboratory cannot be reapproved during the UCMR 3 monitoring period.

NOTE – The only exceptions for the CCC criteria apply to the specific allowance for accepting 

field sample results where no measured target analytes were observed, as applicable and defined 

within the following two methods: 

1. Method 522 - specific and exclusive to the end CCC results and high recoveries for target 

analytes and/or surrogate recovery in that end CCC analysis. 

2. Method 537 - specific to CCC results and high recoveries exclusive to target analytes. 

EPA cautions laboratories that this allowance should rarely be invoked (in less than 5% of 

analytical batches). Laboratories using the high bias allowance more frequently are 

demonstrating a willful disregard for QC criteria by failing to take effective corrective action to 

address a serious systematic problem at their laboratory. A quality conscious laboratory will not 

allow high bias problems to persist and will not find recurring high bias observations in CCC 

standard analysis. During future EPA audits, if there are findings that document chronic use of 

this high bias CCC allowance, the laboratory will risk revocation of EPA approval. 
Page 31 of 50

Table 4. CCC Acceptance Criteria

Analytical Method

Recovery as % of true value

Internal Standard Response

Mid and 

High Level 

CCC 

(Analytes 

>MRL)

Low Level 

CCC

(Analytes

≤MRL)

Surrogate 

Standard

EPA 200.8,

ASTM D5673-10, 

SM 3125

Metals

85 – 115% 50 – 150% NA 60 – 125% the response in the 

calibration blank

EPA 218.7

Chromium-6 85 – 115% 50 – 150% NA NA

EPA 300.1, ASTM 

D6581-08,

SM 4110D

Chlorate

85 – 115%a 75 – 125%b 90 – 115% NA

EPA 522

1,4-Dioxane

70 – 130% 50 – 150% 70 – 130%

±30% the response in the most 

recent previous CCC and ±50% the 

average response in the initial 

calibration

EPA 524.3

VOCs

EPA 537

Perfluorinated 

Compounds

70 - 140% the response in the most 

recent previous CCC and ±50% the 

average response in the initial 

calibration

EPA 539

Hormones

±50% the average response in the 

initial calibration

a Applies to all chlorate methods when the true concentration of the analytes is >10xMRL. b Applies to all chlorate methods when the true concentration of the analyte is ≤10xMRL. 

7.3 Surrogate Requirements and Criteria

Surrogate analyte(s) are required for all UCMR 3 methods, with the exception of the metals 

methods and Method 218.7. A surrogate is a pure analyte that is very unlikely to be found in any 

sample. It is added to the aqueous sample in a known amount before the sample is processed, and 

is measured with the same procedures used to measure other sample components. The purpose of 

a surrogate analyte is to monitor method performance for each sample, from processing through 

analysis. Surrogate recovery must be monitored for each field sample, standard and QC sample. 

Therefore, surrogate analyte(s) must be added to all aqueous samples including LRBs, LFBs, 

LFSMs and LSFMDs, and to all standards. During IDC studies, such as demonstrations of 

accuracy and precision and MRL verifications (see Section 5), the surrogate standard recovery 

must pass the acceptance criteria.

The method-recommended surrogate analytes are listed in Table 5, along with recommended 

concentrations and the analytical acceptance criteria. When the method provides flexibility in the 

selection of the surrogate or its concentration, EPA allows the same flexibility for UCMR 3. 
Page 32 of 50

However, the concentration of each surrogate analyte must be the same in field and QC samples, 

or their extracts/digestates (whichever is introduced into the analytical instrument), as it is in the 

calibration standards. 

Table 5. Surrogate Standards, Concentrations and Criteria

Analytical Method Recommended Surrogate Standard 

Recommended 

Concentration in 

Sample

Acceptance 

Criteria

(% recovery of 

true value)

EPA 200.8,

ASTM D5673-10, 

SM 3125

Metals

NA

EPA 218.7

Chromium-6 NA

EPA 300.1, ASTM 

D6581-08, 

SM 4110D

Chlorate

0.5 mg/mL DCAa 1 mg/L 90 – 115%

EPA 522

1,4-Dioxane

200 μg/mL or 

2000 μg/mL 1,4-Dioxane-d8

10 μg/L

70 – 130%

EPA 524.3

VOCs 

1000 – 2500 μg/mL 

Methyl-t-butyl-ether-d3, BFB, & 

1,2-Dichlorobenzene-d4 

At the mid-level of 

the initial 

calibration for 

analytesb

EPA 537

Perfluorinated 

Compounds

1 – 4 ng/μL

13C-PFHxA, 13C-PFDA, 

& d5-NEtFOSAA

40 – 160 ng/L

EPA 539

Hormones

7.0 μg/mL Ethynylestradiol-d4 70 ng/L

2.5 μg/mL Bisphenol A-d16 25 ng/L

a A surrogate standard must be used, regardless of which method is selected. An alternate to DCA may be used, 

provided it is an analyte not present in drinking water at concentrations greater than 5% of the fortified level. b For example, 5μg/L if using full scan mode and 0.5μg/L if using SIM mode.

The percent recovery of the surrogate in a sample is calculated by comparing the analytically 

measured concentration to the fortified concentration, as in Equation 5: 

 Surrogate % Recovery = Measured [surrogate] X 100% Equation 5

 Expected [surrogate] 

If the surrogate in a specific sample does not meet the acceptance criteria, then the laboratory 

should process a new aliquot of the sample. If this is not possible, then the data for that sample 

are considered suspect for the analysis in question, and is to be flagged as not meeting QC 

criteria. Data for samples with failed surrogate standard recovery must not be reported. If 

possible, the laboratory should process a new aliquot of the sample. 
Page 33 of 50

If the surrogate recovery in an LRB or LFB fail the acceptance criteria, all data for other samples 

in the extraction or in the analytical batch for methods that require the direct analysis of samples 

(i.e., the chlorate methods and EPA 524.3), are invalid and must not be reported. If possible, the 

laboratory should process new aliquots of the affected samples. 

If the surrogate recovery in an LFSM or LFSMD fail the acceptance criteria, but all other batch 

QC pass, only the fortified matrix sample with the failed surrogate is impacted and cannot be 

reported. If the LFSM fails, the LFSMD data should be substituted for the LFSM such that 

accuracy can be assessed. If both LFSM and LFSMD fail, no matrix spike data are reported. 

Surrogate recovery failure of the LFSM and LFSMD do not invalidate the associated sample 

results.

7.4 Internal Standard Requirements and Criteria

Internal standards are required for calibration and quantitation purposes in all UCMR 3 methods, 

with the exception of Method 218.7 and the chlorate methods. An internal standard is a pure 

analyte that is added to a sample or sample extract/digestate in a known amount. It is used to 

measure the relative responses of other method analytes and surrogate standards that are 

components of the same solution. The internal standard must be an analyte that is not a sample 

component. When used, the internal standard is added to all samples, standards, and QC samples 

or their extracts/digestates. During IDC studies, such as demonstrations of accuracy and 

precision and MRL verifications (see Section 5), the internal standard recovery must pass the 

acceptance criteria.

 

For UCMR 3 analysis, EPA is requiring the use of the method specific internal standards to 

ensure the comparability of results amongst laboratories. Table 6 lists the internal standards, 

along with recommended concentrations and the analytical acceptance criteria. When the method 

provides flexibility in the concentration of the internal standard, EPA allows the same flexibility 

for UCMR 3. However, the concentration of each internal standard must be the same in field and 

QC samples, or their extracts/digestates (whichever is introduced into the analytical instrument), 

as it is in the calibration standards.
Page 34 of 50

Table 6. Internal Standards, Concentrations and Criteria

Analytical Method Internal Standard

Recommended 

Concentration Acceptance Criteria

EPA 200.8,

ASTM D5673-10, 

SM 3125

Metals

In, Sc, & Tb 20 - 200μg/L 60 – 125% the response in 

the calibration blank

EPA 218.7

Chromium-6 NA

EPA 300.1, 

ASTM D6581-08,

SM 4110D

Chlorate

NA

EPA 522

1,4-Dioxane THF-d8

500 ng/mL in final 

extract or standard ±30% the most recent 

previous CCC and ±50% 

the average area in the 

initial calibration

EPA 524.3

VOCs 

1,4-Difluorobenzene, 

Chlorobenzene-d5, 

1,4-Dichlorobenzene-d5

Mid-level*

EPA 537

Perfluorinated 

Compounds

13C-PFOA, 13C-PFOS, 

d3-NMeFOSAA

10 - 40 pg/μL in final 

extract or standard

70 - 140% the most recent 

previous CCC and ±50% 

the average area in the 

initial calibration

EPA 539

Hormones

Estriol-d2, 13C6-Estradiol, 

13C2-Ethynylestradiol, 

Testosterone-d3

5 - 20 ng/mL in the 

final extract or 

standard

±50% the average area in 

the initial calibration

* For example, 5 μg/L if using full scan mode and 0.5 μg/L if using SIM mode.

If the internal standard recovery in a sample fails the acceptance criteria, then the results for that 

sample are invalid. Data for samples with failed internal standard criteria must not be 

reported. If possible, the laboratory should process a new aliquot of the sample. 

If the internal standard recoveries in an LRB or LFB fail the acceptance criteria, all data for other 

samples in the extraction or digestion batch, or in the analytical batch for methods that require 

the direct analysis of samples, are invalid and must not be reported. If possible, the laboratory 

should process new aliquots of the affected samples. 

If the internal standard recovery in an LFSM or LFSMD fail the acceptance criteria, but all other 

batch QC pass, only the fortified matrix sample with the failed internal standard is impacted and 

cannot be reported. If the LFSM fails, the LFSMD data should be substituted for the LFSM such 

that accuracy can be assessed. If both LFSM and LFSMD fail, no matrix spike data are to be 

reported. Internal standard recovery failure of the LFSM and LFSMD do not invalidate the 

associated sample results.
Page 35 of 50

7.5 Laboratory Reagent Blank 

Laboratory reagent blanks are required in each batch of field samples for all of the methods 

approved for UCMR 3 monitoring. Methods that require the extraction or digestion of samples to 

prepare them for analysis must process a minimum of one LRB with every batch of 20 or fewer 

field samples and that LRB should be processed with that extraction/digestion batch of field 

samples. Methods involving the direct analysis of samples (i.e., the chlorate methods and EPA 

Methods 524.3 and 218.7) require a minimum of one LRB analyzed with every batch of 20 or 

fewer field samples. For all methods, an LRB is defined as an aliquot of reagent water that is 

treated exactly as a sample, including exposure to all glassware, equipment, solvents, reagents, 

internal standards and surrogate standards that are used with the other samples in the batch. This 

blank determines if method analytes or other interferences are present in the laboratory 

environment, reagents or apparatus. 

 

The goal for UCMR 3 is to ensure that background contamination levels are low enough that 

they do not interfere with accurate measurement of the UCMR 3 analytes. If any of the method 

analytes are detected in the LRB at a concentration greater than the criterion specified in Table 7, 

then no further analyses are to be performed until the source of the problem is identified and 

eliminated. If the source is traced to any material that was used in the preparation of a batch of 

samples, then a new aliquot of each sample is to be prepared. If the samples cannot be reprocessed, then all data for the problem analyte(s) are considered invalid for all samples in the 

batch, and the data is to be flagged as not meeting the QC criteria. Data for samples processed 

with an LRB that fails the criteria must not be reported. 

Contamination problems that occur during sample processing cannot be detected until the 

analysis step. If a problem is discovered, then the data for one or more analytes in all the samples 

in the extraction or digestion batch are lost unless the laboratory has a back-up aliquot of each 

sample to extract. EPA has limited the extraction/digestion batch to 20 field samples to minimize 

the number of samples that may be lost due to a contamination problem. More than one batch of 

samples may be extracted within a day; an LRB must be extracted with each batch. 
Page 36 of 50

Table 7. Laboratory Reagent Blank Criteria

Analytical Method LRB Acceptance Criteria

EPA 200.8,

ASTM D5673-10, 

SM 3125

Metals

The measured concentration of each target analyte must be <1⁄3MRL. 

Internal standard and surrogate standard recoveries must meet the 

criteria specified in Tables 5 and 6, if applicable.

EPA 218.7

Chromium-6

EPA 300.1, 

ASTM D6581-08, 

SM 4110D

Chlorate

EPA 522

1,4-Dioxane

EPA 524.3

VOCs 

The measured concentration of each target analyte must be <1⁄2MRL. 

Internal standard and surrogate standard recoveries must meet the 

criteria specified in Tables 5 and 6.

EPA 537

Perfluorinated Compounds The measured concentration of each target analyte must be <1⁄3MRL. 

Internal standard and surrogate standard recoveries must meet the 

EPA 539 criteria specified in Tables 5 and 6. Hormones

7.6 Laboratory Fortified Blank 

The LFB is an aliquot of reagent water or other blank matrix to which known quantities of the 

method analytes are added in the laboratory. The LFB is processed exactly like a sample, 

including the addition of sample dechlorinators/preservatives. The same lot of reagents and 

internal standard and/or surrogate standard fortifying solutions must be used for all samples 

included in a batch. The same fortification solution used to prepare the LFB should be used to 

prepare the matrix spike samples. The results from the analysis of LFBs determine whether the 

methodology is functioning, and whether the laboratory is capable of making accurate and 

precise measurements. Results from these QC samples provide information about the entire 

process, from sample processing to analyte separation and detection. 

With the exception of EPA 218.7 and EPA 524.3, all other methods approved for UCMR 3 

monitoring require the extraction and analysis of an LFB. Since EPA 218.7 and EPA 524.3 

utilize procedural calibration standards, there is no difference between the LFB and the CCC for 

ONLY these methods. For these two methods, laboratories should prepare the CCCs using the 

same fortification solution used to prepare the Laboratory Fortified Matrix Sample (LFSM). This 

will establish a positive control for matrix spike recoveries.

An LFB must be processed with each extraction or digestion batch of 20 or fewer samples, and 

an LFB must be analyzed for every 20 (or fewer) samples. For UCMR 3, laboratories are 

specifically required to analyze an LFB fortified at or below the MRL prior to analyzing 

field samples. EPA recommends laboratories also process an additional mid- or high-level LFB, 

and analyze it later in the analytical batch. The measured concentration for each UCMR 3
Page 37 of 50

analyte in the LFBs must meet the criteria listed in Table 8. If the recovery for any analyte in the 

low-level LFB (≤MRL) is not within the criteria, the analyst may elect to re-run it. However, if it 

fails again, the analyst must correct the problem before analyzing field samples. If the source is 

traced to any material that was used in the preparation of the batch of samples, then another 

aliquot of each sample must be prepared for analysis. If this is not possible, then all data for the 

problem analyte(s) are considered invalid for all samples in the batch, and is to be flagged as not 

meeting the QC criteria. Data for samples processed with an LFB that fails the criteria must 

not be reported. 

Table 8. Laboratory Fortified Blank Acceptance Criteria

Analytical Method

Recovery as % of true value

Internal Standard Response

Mid and 

High Level 

LFB 

Analytes 

>MRL

Low Level 

LFB 

Analytes 

≤MRL

Surrogate 

Standard

EPA 200.8,

ASTM D5673-10, 

SM 3125

Metals

85 – 115% 50 – 150% NA 60 – 125% the response in the 

calibration blank

EPA 300.1, 

ASTM D6581-08,

SM 4110D

Chlorate

85 – 115%a 75 – 125%b 90 – 115% NA

EPA 522

1,4-Dioxane

70 – 130% 50 – 150% 70 – 130%

±30% the response in the most 

recent previous CCC and ±50% 

the mean area measured in the 

initial calibration

EPA 537

Perfluorinated 

Compounds

70 - 140% the response in the 

most recent previous CCC and

±50% the average area measured

in the initial calibration

EPA 539

Hormones

±50% the average response in the 

initial calibration

a Applies to all chlorate methods when the true concentration of the analytes is >10xMRL. b Applies to all chlorate methods when the true concentration of the analyte is ≤10xMRL. 

7.7 Quality Control Sample (QCS)

All of the UCMR 3 analytical methods require that the laboratory analyze a QCS at least 

quarterly. A QCS is a solution of method analytes of known concentration used to fortify an 

aliquot of reagent water or a sample matrix, obtained from a source external to the laboratory, 

and different from the source of calibration standards. As explained in Section 7.1, EPA 

recommends the concentration of the QCS be near the midpoint of the calibration curve. If a 

source separate from the one used to obtain calibration standards is not available, labs should at 

least purchase standards that are from a different lot than the calibration standards. The QCS is 

used to check laboratory performance. Laboratories may wish to check their performance using 

QCSs containing concentrations that are known to them. Laboratories can prepare their own 
Page 38 of 50

QCSs or purchase them from a commercial supplier (if available). Splitting samples with another 

laboratory is another mechanism for evaluating performance. Use of either or both of these 

procedures is encouraged, especially when a new analyst is developing capabilities to perform a 

method. Table 9 lists the minimum QCS analysis frequency for each UCMR 3 analytical 

method. Labs may analyze a QCS more frequently to monitor method/analyte performance, and 

failure to analyze a QCS at method-stipulated frequencies is viewed as a deficiency/finding 

during a laboratory audit.

Table 9. QCS Frequency Requirements

Analytical Method QCS Frequency Requirements

EPA 200.8

ASTM D5673-10

SM 3125

During IDC (beginning method use)

At least quarterly

EPA 218.7

During IDC (beginning method use)

Each time new calibration standards are prepared

At least quarterly

EPA 300.1

ASTM D6581-08

SM 4110D

During IDC (beginning method use)

At least quarterly

EPA 522

During IDC (beginning method use)

Each time new calibration standards are prepared

At least quarterly

EPA 524.3 During IDC (beginning method use)

At least quarterly

EPA 537

During IDC (beginning method use)

Each time new analyte primary dilution standards are prepared

At least quarterly

EPA 539

During IDC (beginning method use)

Each time new analyte primary dilution standards are prepared

At least quarterly

7.8 Laboratory Fortified Sample Matrix (Spiked Sample)

An LFSM is an aliquot of an environmental sample to which known quantities of the method 

analytes are added in the laboratory. This fortified sample is analyzed exactly like a field sample, 

and its purpose is to determine whether the sample matrix contributes bias to the analytical 

results. The concentrations of the analytes in the unfortified sample matrix must be determined in 

a separate aliquot. 

A technique to evaluate laboratory precision and accuracy for a method is to determine the 

precision of replicate analytical results from the separate processing and analysis of duplicate 

volumes of a sample. However, this technique is only useful when the original sample contains 

background concentrations of the method analytes. Since the laboratory does not know which 

samples may contain measurable concentrations of target analytes, LFSMD samples are used to 

determine the precision of the UCMR 3 monitoring data. 

During the UCMR 3 monitoring period, the samples to be fortified must be UCMR 3 field 

samples, and one set of LFSM/LFSMD/unfortified field sample must be processed with each 

batch. The LFSM/LFSMD fortification concentrations must be alternated between a low and 

mid-level concentration. For example, two analytical batches with a total of 40 field samples will 

require preparation and analysis of two LFSM/LFSMD sets, one set fortified at the low-level and 

one at the mid-level concentration. 
Page 39 of 50

The low-level LFSM/LFSMD fortification concentration must be within ±50% of 

the MRL for each contaminant (e.g., for an MRL of 1.0μg/L, fortification levels 

between 0.50μg/L and 1.5μg/L are acceptable).

The mid-level LFSM/LFSMD fortification concentration should be within ± 20% 

of the mid-level calibration standard for each contaminant. Where possible (i.e., 

when the laboratory has data from previously analyzed samples), the fortification 

concentration should approximate the average concentration observed in previous 

analyses.

If UCMR 3 contaminants are regularly found in field samples at concentrations exceeding 

the MRL, laboratories may find it difficult to fortify that contaminant at the low-level 

concentration. Laboratories may need to apply their experience and adjust their fortification 

to levels more appropriate and respective of native levels and may also first need to analyze 

a field sample prior to selecting the appropriate level for fortification. 

There are no target analyte recovery acceptance criteria specified for LFSM/LFSMD results. 

Data should not be rejected based on the recovery of fortified target analytes or the 

precision between the LFSM and LFSMD, provided that the analysis of the fortified sample 

yields acceptable internal standard and surrogate standard recoveries and all other batch QC are 

valid. LFSM/LFSMD results are to be reported to EPA’s electronic data reporting system.

7.9 Analytical Sequence

The sequence with which UCMR 3 field and QC samples are analyzed is important for assessing 

system performance. As described in Section 7.2, each analysis batch must begin with the 

analysis of a CCC at or below the MRL for each of the UCMR 3 analytes targeted by the 

method. This CCC≤MRL is to be analyzed whether or not the initial calibration was generated 

the same day. Following the CCC≤MRL analysis, the LRB is to be analyzed, then the 

LFB≤MRL, and then up to 10 field samples. After 10 field samples, the calibration must be 

verified by the analysis of a mid- or high-level CCC. If this CCC passes the criteria, then up to 

10 additional field samples may be analyzed. The batch must end with the analysis of a mid- or 

high-level (whichever was not analyzed after the 10th sample) CCC. If a second batch is started 

immediately after one analytical batch is completed, it must begin with the analysis of a 

CCC≤MRL. 
Page 40 of 50

Example 2 illustrates a valid analysis sequence for Method 537 that will meet the QC 

requirements. It provides suggestions for corrective action if the criteria are not met. 

Example 2. Valid Analysis Sequence for Method 537

Injection 

#

Sample 

Description Acceptance Criteriaa Corrective Action

1 CCC≤MRL Recovery for each target analyte is 

50-150% of the true value. 

Instrument maintenance to recover 

sensitivity, followed by recalibration

and verification of sensitivity by a low 

level CCC. 

2 LRB All target analytes <1⁄3MRL 

concentration

Identify and correct source of 

contamination. 

3 LFB≤MRLb 50-150% of the true value for each 

target analyte.

Identify and correct source of problem.

4

through

13

Field Samples 

1-10

Positive ID of an analyte is verified 

if the peak passes the retention time 

criterion and mass spectral 

identification is confirmed.

Identify and correct source of problem.

14 Mid-level CCCc Recovery for each target analyte is 

70-130% of the true value.

Instrument maintenance, followed by 

recalibration.

15 LFSM of a 

Field Sample

At low-level fortification 

concentrations, 50-150% recovery. 

At mid-level fortification 

concentrations, 70-130% recoveryd

. 

If % recovery is out of the designated 

range, but laboratory performance for all 

other QC is acceptable, the recovery 

problem is judged to be matrix related, 

but is still reportable.

16 LFSMD of 

Field Sample

RPD between LFSM and LFSMD 

≤50% for low-level fortification 

concentrations and ≤30% for midlevel fortification concentrationsd

. 

If % recovery is out of the designated 

range, but laboratory performance for all 

other QC is acceptable, the recovery 

problem is judged to be matrix related, 

but is still reportable.

17

through

28

Field Samples 

11-20

Positive ID of an analyte is verified 

if the peak passes the retention time 

criterion and mass spectral 

identification is confirmed.

Identify and correct source of problem.

29 Final high-level 

CCCc

Recovery for each analyte is 70-

130% of the true value.

Instrument maintenance, followed by 

recalibration. a In all field and QC samples, and standards for Method 537: The area for the internal standard must be 70-

140% of the area in the most recent CCC and 50-150% of the average area measured during the initial calibration. 

Surrogate recovery must be 70-130% of the true value. b Quality conscious labs may choose to include an additional LFB, at rotating concentrations, later in the analysis 

batch. The criterion for LFBs fortified at a concentration >MRL is 70-130% of the true value for each target 

analyte. 

c Subsequent to the initial CCC≤MRL, CCC concentrations are to be rotated between the mid and high

concentrations. d Failing these LFSM/LFSMD target analyte recovery criteria does not invalidate the analysis batch under UCMR 

3. See Section 7.8 for the specifications for low and mid-level fortification concentrations. 
Page 41 of 50

Section 8. Sample Handling Requirements

Laboratory personnel should be very familiar with the sample collection, preservation, and 

storage requirements. Laboratories performing UCMR 3 analyses for a large public water system 

(PWS) should communicate with the PWS and ensure their client has a clear understanding of 

the UCMR 3-specific requirements for sample collection, preservation and transportation. It 

should also be noted that UCMR 3 samples must not be composited (i.e., combined, mixed or 

blended); samples from each sampling point must be collected, preserved and processed 

separately.

PWSs that must ship the samples for analysis should recognize that samples must be collected 

early enough in the day to allow adequate time to send these samples for overnight delivery to 

the laboratory. The PWS should avoid collecting samples on Thursday and should not collect 

samples on Friday, Saturday, or Sunday unless special arrangements have been made for the 

receipt of samples at the laboratory within 48-hours of collection. Laboratories must examine the 

samples when they arrive and determine if the proper shipping conditions were used. 

Special precautions for hormone (EPA 539) sampling: These sampling precautions are 

adapted from the US Geological Survey sampling protocols for hormones. to reduce the 

likelihood of sample contamination (USGS 2004). 

• On the day of sampling, persons collecting samples should avoid contact or consumption 

of hormonal substances (medications, prescription drugs, etc.); 

• Samplers should wear powderless nitrile laboratory gloves during sampling and 

processing; 

• Samplers should avoid breathing directly over open samples; 

• Samplers should avoid direct contact with the sample; and 

• Laboratory analysts should follow the same precautions. 

Special note for chlorate (EPA 300.1) sampling: If a water system uses chlorine dioxide as a 

disinfectant, samples must be sparged at the time of collection. The sample should be collected 

in a clean, wide mouth flask. The sparging gas should be an inert gas such as a lecture bottle of 

nitrogen or helium fitted with a regulator and connected to a disposable glass Pasteur pipette 

with PVC tubing. The gas flow should be adjusted to produce a steady flow of bubbles. After 10-

15 minutes of sparging, the chlorine dioxide residual should have been effectively removed from 

the sample. The sample can then be poured from the flask into the sample bottle containing the 

EDA preservative. 

8.1 Field Blanks

Some of the UCMR 3 samples are susceptible to contamination from outside sources. EPA is 

requiring the collection of field blanks (FBs) for all methods with the exception of chlorate, 

hexavalent chromium and 1,4-dioxane. If the target analyte is found in the field sample, a field 

blank must be analyzed. Field blanks are to be processed, extracted and analyzed in exactly the 

same manner as the field sample. If the field blank level is at a concentration greater than 1/3 the 

MRL, then field samples collected with that field blank are invalid and new samples must be 

collected. 
Page 42 of 50

Table 10. Field Blanks

Analytical Method Collection Requirement

EPA 200.8

ASTM D5673-10

SM 3125

Fill a sample bottle with reagent water and preservatives in the lab, seal 

and ship with field sample bottles. Open the bottle at the sampling site, 

then seal and ship with field sample bottles.

EPA 218.7 Not required

EPA 300.1

ASTM D6581-08

SM 4110D

Not required

EPA 522 Not required

EPA 524.3

Duplicate field blanks are required. Fill two sample bottles with reagent 

water and preservatives in the lab, seal and ship with field sample bottles. 

DO NOT OPEN in the field, these field blanks must remain sealed until 

analysis.

EPA 537

Fill a sample bottle with reagent water and preservatives in the lab, seal 

and ship with field sample bottles. Also include an empty sealed bottle (no 

preservatives). At the sampling site, open the bottle containing the reagent 

water and pour it into the empty bottle.

EPA 539

Fill a sample bottle with reagent water and preservatives in the lab, seal 

and ship with field sample bottles. Also include an empty sealed bottle (no 

preservatives). At the sampling site, open the bottle containing the reagent 

water and pour it into the empty bottle.

8.2 Sample Transport and Storage 

Samples should arrive at the laboratory packed on ice or with frozen gel packs in a sample bottle 

constructed of appropriate material as described in the analytical method. Samples that are 

shipped from the PWS should be sent by priority overnight delivery to the laboratory. UCMR 3 

samples that arrive at the laboratory within 48 hours of collection must not exceed 10oC. 

Samples with water temperatures significantly above 10oC at the time of collection (e.g., summer 

sampling events with elevated ambient water temperature), may be iced or refrigerated for a 

period of time prior to shipping to ensure the laboratory receipt temperature criteria are met. 

Samples that arrive at the laboratory on the same day of sample collection (exclusively due to the 

close proximity of a PWS to the laboratory), may not yet have stabilized to 10oC or less when 

they arrive at the lab. These samples are acceptable ONLY if packed on ice or with frozen gel 

packs immediately after sample collection and hence, delivered while samples are in the process 

of reaching an equilibrium temperature less than 10oC. Samples must not be analyzed if they 

were not shipped properly. Table 11 provides the temperature and sample bottle material criteria 

for UCMR 3 samples. Some UCMR 3 methods require protecting the sample from exposure to 

light. The use of amber sample bottles is effective, but labs and/or PWSs may elect to wrap clear 

glass bottles with foil. Laboratories are responsible for ensuring that their client PWSs utilize the 

proper sample containers. If improper containers are used (e.g., plastic bottles instead of glass), 

the laboratory should notify the PWS that a replacement sample must be collected using proper 

containers.
Page 43 of 50 

Table 11. Requirements for Sample and Extract Storage Temperatures

Analytical Method Sample Bottle Material Temperature 

Specification for Samples

Temperature 

Specification for Extracts

EPA 200.8

ASTM D5673-10

SM 3125

Plastic OR glass bottles

Shipped on ice or with 

frozen gel packs, received 

at the lab at 10oC or less 

within 48 hours of 

collection. Refrigerated at 

6oC or less after arrival at 

the laboratory or within 48 

hours of collection, 

whichever is sooner.

N/A

EPA 218.7 HDPE OR propylene 

copolymer bottles N/A

EPA 300.1

ASTM D6581-08

SM 4110D

Plastic OR glass bottles N/A

EPA 522 Glass bottle with PTFE lined 

screw cap

≤ -5oC, amber vial

EPA 524.3

Amber glass volatile organic 

analysis (VOA) vials fitted with 

PTFE-faced silicone septa and 

polypropylene screw caps

N/A

EPA 537 Polypropylene bottles with 

polypropylene screw caps Room temperature

EPA 539 Amber glass bottle with PTFE 

lined screw cap ≤ 0oC

8.3 Sample Preservation

The stability of the UCMR 3 samples is dependent upon proper preservation and/or 

dechlorination. Both the laboratory and PWS are responsible for ensuring that the UCMR 3

samples are properly preserved/dechlorinated as stipulated in the analytical methods. 

Dechlorination and preservation are required at the time of sample collection. There must 

be clear communication between the laboratory and PWS that assures correct preservatives 

(including acid, buffer, or microbial inhibitor, as specified in the method and in Table 12) and 

dechlorinators are used. If the laboratory provides bottles containing the appropriate chemical(s) 

to the sampler, then the sampler should be notified that the bottles cannot be rinsed or permitted 

to overflow at the time of sample collection. Further, the lab must adhere to any time limits 

stipulated in the analytical method that the chemical(s) will be stable in the sample bottle. 

Upon sample receipt, laboratories should verify preservation/dechlorination of each sample by 

conducting the appropriate check listed in Table 12. These checks should be performed at the 

laboratory, using a small aliquot of sample. Method 524.3 is an exception, since immediately 

checking for preservation upon receipt would compromise the sample, so for this VOC method 

the checks must be performed after analysis to avoid loss of analytes. (Note: To avoid possible 

sample contamination, pH probes or other instruments should never be inserted into the entire 

volume of sample.) If the criteria are not met, the samples must not be analyzed, and a new 

sample must be collected from the PWS. 

To verify pH, either a standard pH meter or test strips are acceptable. The verification of the 

absence of free chlorine is qualitative, provided the laboratory can measure the presence of free 

chlorine at and above 0.1 mg/L. Note that a small aliquot of the sample should be used to test 

pH and/or chlorine content (i.e., probes and/or test strips should not be placed into the bulk 

sample bottle) to prevent sample contamination. 
Page 44 of 50

Table 12. Sample Preservatives and Dechlorinating Agents (Concentration in Sample) and 

Acceptance Criteria

Analytical Method Chemical (concentration) Sample Check/Criteria

EPA 200.8

ASTM D5673-10

SM 3125

2 mL HNO3 per L of samplea pH < 2

EPA 218.7

Liquid: (NH4)2SO4 (3.3 g in 25mL reagent 

H2O)/NH4OH (6.5 mL concentrate in 100 mL 

reagent H2O); 1 mL of each in 100 mL sampleb,d 

OR

Solid: Na2CO3 (13.3 mg)/NaHCO3 (10.5 mg)/ 

(NH4)2SO4 (33 mg) in 100 mL sampleb,d 

Absence of free chlorinef 

(< 0.1 mg/L)

pH > 8 

EPA 300.1

ASTM D6581-08

SM 4110D

50 mg/mL ethylene diamine (EDA)c; sparge sample 

with inert gas (He, Ar, N2) prior to EDA addition if 

plant uses chlorine dioxide (ClO2) for treatment

Absence of free chlorine f

(< 0.1 mg/L)

EPA 522

50 mg/L sodium sulfiteb (solid shipped in sample 

bottle)

1 g/L sodium bisulfatee (added in field after sodium 

sulfite has been dissolved)

Absence of total chlorine 

(< 0.1 mg/L)

pH < 4

EPA 524.3 0.625 g/L ascorbic acidb

5 g/L maleic acid

Absence of free chlorine 

(< 0.1 mg/L)

pH∼2

EPA 537 5.0 g/L trizmab,d Absence of free chlorine 

(< 0.1 mg/L)

EPA 539 80 mg/L sodium thiosulfateb

65 mg/L 2-mercaptopyridine-1-oxide, sodium salte

Absence of free chlorine

(< 0.1 mg/L) a Acid may be added in the field or in the lab prior to analysis. If acid is added at the lab, the sample must be 

held for 16 hours and pH verified again prior to processing. b dechlorinator

c preservative

d buffer

e microbial inhibitor

f Confirm “Absence of free chlorine” by careful observation. The sample may contain total chlorine present as 

chloramine, due to chemical reactions of free chlorine as a disinfectant with ammonium (NH4

+

) in 218.7 or 

EDA in 300.1. Typical DPD (N,N Diethyl-1,4 Phenylenediamine) tests will work but require immediate 

interpretation since over time a false positive free chlorine result may develop. 

8.4 Maximum Holding Times

The laboratory is responsible for ensuring each sample is analyzed within the required holding 

time. A list of applicable maximum (i.e., not to exceed) holding times is presented in Table 13. 

These maximum holding times are applicable for samples that are properly preserved and are 

stored in appropriate sample containers at the appropriate temperatures. The aqueous sample 

holding time prior to extraction begins on the day the sample is collected. The sample extract 

holding time begins on the day the sample extraction was initiated. 

If a UCMR 3 sample is not extracted or analyzed within the times specified in Table 8.4, then the 

data for the sample must not be reported. The laboratory should indicate to the PWS that the 

sample was invalidated due to a holding time problem, and should request a resample. 

The published UCMR 3 analytical methods provide additional information concerning 

recommended sample collection and holding procedures for samples. These procedures must be 

observed for UCMR 3 samples. 
Page 45 of 50

Table 13. Maximum Holding Times for Samples and Extracts

Analytical Method

Holding Time for Sample 

(days)

Holding Time for Extract 

(days)

EPA 200.8

ASTM D5673-10 

SM 3125

28 28 (recommended) 

EPA 218.7 14 N/A

EPA 300.1

ASTM D6581-08 

SM 4110D

28 N/A

EPA 522 28 28 

EPA 524.3 14 N/A

EPA 537 14 28 

EPA 539 28 28 

8.5 Laboratory Errors or Sampling Deviations

If an error occurs, either in sampling or at the laboratory, which precludes the reporting of valid 

data, a resample must be collected within 30 days of the PWS being notified of the error. This 

resampling is not for confirmation sampling, but rather to correct the sampling or laboratory 

error. If resampling cannot be performed, then the PWS should be instructed to notify EPA’s 

UCMR Sampling Coordinator via e-mail at UCMR_Sampling_Coordinator@epa.gov or the 

State. 
Page 46 of 50

Section 9. References

ASTM Standard D5673-10. Standard Test Method for Elements in Water by Inductively Coupled 

Plasma – Mass Spectrometry. American Society for Testing and Materials (ASTM), West 

Conshohocken, PA. 2005. Available at http://www.astm.org/Standards/D5673.htm

ASTM Standard D6581-08. Standard Test Methods for Bromate, Bromide, Chlorate, and 

Chlorite in Drinking Water by Suppressed Ion Chromatography. ASTM, West Conshohocken, 

PA. 2008. Available at http://www.astm.org/Standards/D6581.htm

EPA Method 200.8. Determination of Trace Elements in Waters and Wastes by Inductively 

Coupled Plasma – Mass Spectrometry, Revision 5.4, EMMC Version. Environmental 

Monitoring Systems Laboratory, Office of Research and Development (ORD), EPA, Cincinnati, 

Ohio 45268. Available at https://www.nemi.gov/

EPA Method 300.1. Determination of Inorganic Anions in Drinking Water by Ion 

Chromatography. National Exposure Research Laboratory (NERL), ORD, EPA, Cincinnati, 

Ohio 45268. Available for download at 

http://water.epa.gov/scitech/drinkingwater/labcert/analyticalmethods_ogwdw.cfm

EPA Method 522. Determination of 1,4-Dioxane by Solid Phase Extraction (SPE) and Gas 

Chromatography/Mass Spectrometry (GC/MS) with Selected Ion Monitoring (SIM), Version 1.0, 

September, 2008. EPA/600/R-08/101. NERL, ORD, EPA, Cincinnati, Ohio 45268. Available for 

download at http:/www.epa.gov/nerlcwww/ordmeth.htm

EPA Method 524.3. Measurement of Purgeable Organic Compounds in Water by Capillary 

Column Gas Chromatography/Mass Spectrometry, Version 1.0, June 2009. EPA 815-B-09-009. 

TSC, OGWDW, EPA, Cincinnati, Ohio 45268. Available for download from 

http://water.epa.gov/scitech/drinkingwater/labcert/analyticalmethods_ogwdw.cfm

EPA Method 537. Determination of Selected Perfluorinated Alkyl Acids in Drinking Water by 

Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS), 

Version 1.1, September 2009. EPA Document #EPA/600/R-08/092. NERL, ORD, EPA, 

Cincinnati, Ohio 45268. Available for download at 

http://www.epa.gov/nerlcwww/ordmeth.htm

EPA Method 539. Determination of Hormones in Drinking Water by Solid Phase Extraction 

(SPE) and Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry (LCESI-MS/MS), Version 1.0, November 2010. EPA Document #815-B-10-001. TSC, OGWDW, 

EPA, Cincinnati, Ohio 45268. Available at 

http://water.epa.gov/scitech/drinkingwater/labcert/analyticalmethods_ogwdw.cfm

EPA QA/R-2. EPA Requirements for Quality Management Plans (QA/R-2). EPA Document 

#EPA/240/B-01/002. Office of Environmental Information (OEI), EPA, Washington, DC 20460. 

Available at http://www.epa.gov/quality/qmps.html

EPA QA/R-5. EPA Requirements for Quality Assurance Project Plans (QA/R-5) EPA Document 

#EPA/240/B-01/003. OEI, EPA, Washington, DC 20460. Available for download from 
Page 47 of 50

http://www.epa.gov/quality/qs-doc/r5-final.pdf

Technical Basis for the Lowest Concentration Minimum Reporting Level (LCMRL) Calculator, 

December 2010. EPA Document #815-R-11-001. TSC, OGWDW, EPA, Cincinnati, Ohio 

45268. Available for download from 

http://water.epa.gov/scitech/drinkingwater/labcert/analyticalmethods_ogwdw.cfm

SM Method 3125, 21st Ed. Metals by Inductively Coupled Plasma/Mass Spectrometry (2005). 

Available for purchase at 

http://www.standardmethods.org/store/ProductView.cfm?ProductID=211

SM Method 4110D, 21st Ed. Ion Chromatographic Determination of Oxyhalides and Bromide 

(2005). Available for purchase at 

http://www.standardmethods.org/store/ProductView.cfm?ProductID=31

US Geological Survey, Processing of water samples (ver. 2.2): U.S. Geological Survey 

Techniques of Water-Resources Investigations, Book 9, Chapter A5 Section 5.6.1.F, 

"Wastewater, pharmaceutical, and antibiotic compounds," April 2004, Available at

http://water.usgs.gov/owq/FieldManual/chapter5/5.6.1.F_v-1.1_4-03.pdf
Page 48 of 50

Appendix A. Requirements for UCMR 3 Metal Analysis 

Table 14. Determination of Metals for UCMR 3 based on EPA Method 200.8 Rev. 5.4

ANALYTES Natural Isotopes 

(monitor all of these) 

% Relative 

Abundance

Additional Isotopes 

to Monitor

Isotope to 

Report

Elemental & Molecular Correction Equations

Vanadium (V)

IS: Sc, In, Tb

50 (Ti, Cr)

51

0.250

99.750

52, 53 51 (1.000) (51C) – (3.127) [(53C) – (0.113) (52C)]

Isobaric polyatomic correction for molecular ions produced by a chloride 

matrix. 

Chromium (Cr)

IS: Sc, In, Tb

50 (Ti, V)

52

53

54 (Fe)

4.345

83.789

9.501

2.365

47, 48, 49, 51, 56 52 (1.000) (52C)

Cobalt (Co)

IS: Sc, In, Tb

59 100 --- 59 (1.000) (59C)

Strontium (Sr)

IS: In, , Sc, Tb

84 (Kr)

86 (Kr)

87 (Rb)

88

0.56

9.86

7.00

82.58

83, 85 88 (1.000) (88C)

Molybdenum 

(Mo)

IS: In, Sc, Tb

92 (Zr)

94 (Zr)

95

96 (Zr, Ru)

97

98 (Ru)

100 (Ru)

14.84

9.25

15.92

16.68

9.55

24.13

9.63

90, 99, 101 98 (1.000) (98C) – (0.111) (101C)

Elemental correction for Ru on Mo.

INTERNAL STANDARDS

Scandium (Sc) 45 100 45 45 (1.000) (45C)

Background molecular ions may interfere.

Indium (In) 113 (Cd)

115 (Sn)

4.3

95.7

106, 108, 111, 114, 

118, 120

115 (1.000) (115C) – (0.016) (118C)

If Tin present, use the isobaric elemental correction for Tin.

Terbidium (Tb) 159 100 159 159 (1.000) (159C)

For the analytes listed in the first column of the Table above, monitor all of the isotopes listed in the second and fourth columns. Report using the isotopes listed in the fifth 

column using the Elemental & Molecular Correction Equations listed in the sixth column. The internal standards listed with the analytes are in order of suggested use, but accept 

any of the internal standards listed in the table.

Follow EPA Method 200.8 Revision 5.4 for Total Recoverable Analytes in Aqueous Samples with the following additions/exceptions:

Method Section 8.0 Sample container: plastic or glass

 Sample size: 100 mL

11.0 Use section 11.2.2 – must digest samples regardless of turbidity

11.2.3 Omit the use of Hydrochloric Acid (HCl)

11.2.8 Omit 11.2.8
Page 49 of 50

Appendix B. Lowest Concentration Minimum Reporting Level 

(LCMRL) Data used to Determine 

UCMR 3 Minimum Reporting Levels (MRLs)

Hormones Lab A Lab B Lab C MRL (μg/L)

17-β-estradiol 0.00020 0.00020 0.00034 0.0004

17-α-ethynylestradiol 

(ethinyl estradiol)

0.00014 0.00018 0.0013 0.0009

estriol 0.00096 0.00035 0.00028 0.0008

equilin 0.00012 0.00078 0.0030 0.004

estrone 0.00018 0.00013 0.0029 0.002

testosterone 0.000068 0.000036 0.000062 0.0001

4-androstene-3,17-dione 0.000093 0.000079 0.00037 0.0003

Perfluorinated 

Compounds

Lab A Lab B Lab C MRL (μg/L)

perfluorooctane sulfonic 

acid (PFOS)

0.013 0.0072 0.048 0.04

perfluorooctanoic acid 

(PFOA)

0.018 0.0054 0.00054 0.02

perfluorononanoic acid 

(PFNA)

0.012 0.0067 0.00080 0.02

perfluorohexane sulfonic 

acid (PFHxS)

0.018 0.010 0.033 0.03

perfluoroheptanoic acid 

(PFHpA)

0.010 0.0052 0.00082 0.01

perfluorobutanesulfonic acid 

(PFBS)

0.056 0.015 0.077 0.09

Chlorate Lab A Lab B Lab C MRL (μg/L)

chlorate 14 5.9 1.67 20

Metals Lab A Lab B Lab C MRL (μg/L)

cobalt 1.1 0.036 0.19 1.

molybdenum 0.62 0.076 0.51 1.

vanadium 0.070 0.048 0.25 0.2

strontium 0.18 0.11 0.33 0.3

Total Chromium Lab A Lab B Lab C Lab D MRL (μg/L)

total chromium 0.12 0.073 0.24 0.16 0.2

VOCs Lab A Lab B Lab C Lab D MRL (μg/L)

chlorodifluoromethane 0.056 0.012 0.024 0.092 0.08

chloromethane 0.15 0.14 0.070 0.12 0.2

1,3-Butadiene 0.092 0.044 0.056 0.084 0.1

bromomethane 0.25 0.059 0.058 0.10 0.2

1,1-Dichloroethane 0.015 0.019 0.014 0.026 0.03

bromochloromethane 0.0064 0.058 --- 0.030 0.06

1,2,3-Trichloropropane 0.010 0.025 0.017 0.034 0.03
Page 50 of 50

1,4 Dioxane Lab A Lab B Lab C MRL (μg/L)

1,4-Dioxane 0.018 0.046 0.076 0.07

Chromium-6 Lab A Lab B Lab C Lab D Lab E Lab F Lab G Lab H Lab I MRL (μg/L)

chromium-6 0.022 0.032 0.0022 0.014 0.010 0.031 0.026 0.0065 0.031 0.03

Note: There were as many as nineteen different laboratories participating in the LCMRL studies 

and generated these data, with a minimum of three labs for each method. Laboratory 

designations of A, B, C, etc. are arbitrary and do not represent the same laboratory participant for 

the various methods evaluated.