f/EPA
United States
Environmental Protection
Agency
Analytical Feasibility Support Document for
the Third Six-Year Review of Existing
National Primary Drinking Water
Regulations: Chemical Phase Rules and
Radionuclides Rules
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Office of Water (4607M)
EPA-810-R-16-005
December 2016
www. epa. gov/ safewater
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Disclaimer
This document is not a regulation. It is not legally enforceable and does not confer legal rights or
impose legal obligations on any party, including EPA, states or the regulated community. While
EPA has made every effort to ensure the accuracy of any references to statutory or regulatory
requirements, the obligations of the interested stakeholders are determined by statutes,
regulations or other legally binding requirements, not this document. In the event of a conflict
between the information in this document and any statute or regulation, this document would not
be controlling.
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Table of Contents
Executive Summary ES-1
1 Introduction 1-1
2 Background 2-1
2.1 SDWA Requirements for Analytical Methods 2-1
2.2 PQL Determination Methods for the SDWA Contaminants 2-2
2.3 Operational Details of the PE/PT Programs 2-2
2.4 Efforts Made to Obtain PT Data 2-3
3 Representativeness of Available PT Data 3-1
4 Identification of Regulated Analytes for PQL Assessment 4-1
5 Six-Year Review 3 Assessment Methodology 5-1
5.1 Data Available for PQL Assessments 5-1
5.2 Data Assessment Methodology 5-6
6 Results of PQL Assessment 6-1
6.1 Category 1: Analytes with MCL Equal to the Current PQL and Thus the PQL is
Limiting 6-2
6.1.1 PQL Assessment Supports Reduction of the Current PQL 6-2
6.1.2 PQL Assessment May Supports Reduction of the Current PQL 6-2
6.1.3 PQL Assessment Does Not Support Reduction of the Current PQL or
Data is Insufficient to Reach a Conclusion 6-2
6.2 Analytes with MCL Greater Than the Current PQL and Thus It is Technically
Feasible to Reduce an MCL 6-17
6.2.1 PQL Assessment Supports Reduction of the Current PQL 6-18
6.2.2 PQL Assessment May Support Reduction of the Current PQL 6-21
6.2.3 PQL Assessment Does Not Support Reduction of the Current PQL or
Data is Insufficient to Reach a Conclusion 6-21
7 References 7-1
the Third Six-Year Review
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Table of Exhibits
Exhibit ES. 1: Analytical Feasibility Assessment Summary for Analytes with MCL Equal to
Current PQL 2
Exhibit ES.2: Analytical Feasibility Assessment Summary for Analytes with MCL Greater than
the Current PQL 3
Exhibit 3.1: Qualitative Comparison of Two Data Sources 3-1
Exhibit 4.1: US EPA National Primary Drinking Water Standards and Analytical Information 4-1
Exhibit 5.1: Availability of Six-Year Review 1 PE Data and Six-Year Review 2 and Six-Year
Review 3 PT Data for Regulated Analytes 5-1
Exhibit 6.1: Analytical methods for Chlordane 6-3
Exhibit 6.2: Evaluation of PT Data - Chlordane 6-4
Exhibit 6.3: Analytical Methods for DBCP 6-5
Exhibit 6.4: Evaluation of PT Data - DBCP 6-6
Exhibit 6.5: Analytical Methods for Dioxin 6-7
Exhibit 6.6: Evaluation of PT Data - Dioxin 6-7
Exhibit 6.7: Analytical Methods for Heptachlor 6-8
Exhibit 6.8: Evaluation of PT Data - Heptachlor 6-9
Exhibit 6.9: Analytical Methods for Heptachlor Epoxide 6-10
Exhibit 6.10: Evaluation of PT Data - Heptachlor Epoxide 6-11
Exhibit 6.11: Analytical Methods for Pentachlorophenol 6-12
Exhibit 6.12: Evaluation of PT Data - Pentachlorophenol 6-13
Exhibit 6.13: Analytical Methods for Thallium 6-14
Exhibit 6.14: Evaluation of PT Data - Thallium 6-15
Exhibit 6.15: Analytical Methods for Toxaphene 6-16
Exhibit 6.16: Evaluation of PT Data - Toxaphene 6-17
Exhibit 6.17: Analytical Methods for cis-l,2-dichloroethylene 6-18
Exhibit 6.18: Evaluation of PT Data - cis-l,2-Dichloroethylene 6-19
Exhibit 6.19: Analytical Methods for Toluene 6-20
Exhibit 6.20: Evaluation of PT Data - Toluene 6-21
Exhibit 6.21: Analytical Methods for Carbofuran 6-22
Exhibit 6.22: Evaluation of PT Data - Carbofuran 6-23
Exhibit 6.23: Analytical Methods for Cyanide 6-24
Exhibit 6.24: Evaluation of PT Data - Cyanide 6-25
Exhibit 6.25: Analytical Methods for Hexachlorocyclopentadiene 6-26
Exhibit 6.26: Evaluation of PT Data - Hexachlorocyclopentadiene 6-27
Exhibit 6.27: Analytical Methods for Oxamyl 6-28
Exhibit 6.28: Evaluation of PT Data - Oxamyl 6-29
Exhibit 6.29: Analytical Methods for Selenium 6-30
Exhibit 6.30: Evaluation of PT Data - Selenium 6-31
Exhibit 6.31: Analytical Methods for Xylenes 6-32
Exhibit 6.32: Evaluation of PT Data - Xylenes 6-33
Exhibit 6.33: Analytical Feasibility Assessment Summary for Analytes with MCL Equal to the
Current PQL 6-35
Exhibit 6.34: Analytical Feasibility Assessment Summary for Analytes with MCL Greater than
the Current PQL 6-37
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Abbreviations and Acronyms
ASTM
American Society for Testing and Materials
CCGC
Capillary Column Gas Chromatography
CBI
Confidential Business Information
CASRN
Chemical Abstract Services Registry Number
DAI
Direct Aqueous Injection
DL
Detection Limit
DW
Drinking Water
ECD
Electron Capture Detector
ECGC
Electron Capture Gas Chromatography
ELCD
Electrolytic Conductivity Detector
EPA
Environmental Protection Agency
FR
Federal Register
GC
Gas Chromatography
HPLC
High Performance Liquid Chromatography
HRGC
High Resolution Gas Chromatography
HRMS
High Resolution Mass Spectrometry
ICP
Inductively Coupled Plasma
LLE
Liquid-Liquid Extraction
LSE
Liquid-Solid Extraction
MCL
Maximum Contaminant Level
MCLG
Maximum Contaminant Level Goal
MDL
Method Detection Limit
ME
Microextraction
MS
Mass Spectrometry
N/A
Not Available
NELAC
National Environmental Laboratory Accreditation Conference
NPDWR
National Primary Drinking Water Regulation
OIA
01 Analytical
PE
Performance Evaluation
PQL
Practical Quantitation Level
PT
Proficiency Testing
PTRL
Proficiency Testing Reporting Limit
SDWA
Safe Drinking Water Act
SM
Standard Methods
SPE
Solid-Phase Extraction
TCR
Total Coliform Rule
WS
Water Supply
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Acknowledgements
Thanks to Mr. Jason Campbell from Phenova and Mr. A1 Ramsay from Environmental
Resources Associates, Inc. for providing the necessary data for evaluation and supporting EPA in
this analysis.
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Executive Summary
The Safe Drinking Water Act (SDWA), as amended in 1996, requires the Environmental
Protection Agency (EPA) to review and revise, if appropriate, existing National Primary
Drinking Water Regulations (NPDWRs). The review involves consideration of five key
elements, as appropriate: health effects, analytical and treatment feasibility, implementation-
related issues, occurrence and exposure, and economic impact. This report addresses the
analytical feasibility aspect of the review which has been based on the laboratories' analytical
performance data generated as part of EPA's certification program for drinking water
laboratories. This analytical feasibility assessment is based on the recent analytical performance
data collected during the third six-year review (period of 2008-2014). Efforts are also made to
determine if the analytical performance assessments based on the laboratory data are supported
by the adoption of improved methods or revision of existing methods since the last review. The
goal is to create a comprehensive document to address all regulated chemical analytes for which
data is available.
Analytical Performance Assessment Based on the Laboratories' Analytical Performance Data
The Practical Quantitation Level (PQL) assessments are presented by way of linear regressions
that plot laboratory passing rate versus true concentration of the analyte. The PQL is defined as
"the lowest achievable level of analytical quantitation during routine laboratory operating
conditions within specified limits of precision and accuracy" (USEPA, 1985a). The PQL is set at
a concentration where 75 percent of laboratories achieve results within a specific range around
the spike value or acceptance criteria. PQL determination can be a useful tool in assessing
whether promulgated PQLs can be reduced as a result of improved laboratory performance over
time. The PQL incorporates quantitation, precision and bias, normal operations of a laboratory
and the fundamental need to have a sufficient number of laboratories available to conduct
compliance monitoring analyses (USEPA, 1985b; USEPA, 1987; USEPA, 1989).
The current report includes PQL assessments for available Performance Evaluation (PE) data
generated under The NELAC Institute (TNI) Proficiency Testing (PT) program. Out of the seven
TNI-accredited PT providers that were approached to provide PT data, only two PT providers,
i.e., Environmental Resource Associates, Inc. (ERA) and Phenova were able to provide the
requested information. After an initial review and analysis conducted under the Six-Year Review
3 Protocol, PQL analysis was performed on 16 analytes. The results for the 16 regulated analytes
are categorized into two subsets based on the limitation of the PQL for setting the Maximum
Contaminant Level (MCL) at the time of promulgation: 1) analytes with MCL equal to the
current PQL and thus the PQL is limiting and 2) analytes with MCL greater than the current PQL
and thus it is technically feasible to reduce an MCL.
The recommendations for the PQL assessment for the 16 analytes are as follows:
For eight analytes, the PQL is equal to the MCL and hence the PQL is limiting (refer to
Exhibit ES.l for results of the PQL analyses).
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For all eight analytes (chlordane, l,2-dibromo-3-chloropropane, dioxin, heptachlor, heptachlor
epoxide, pentachlorophenol, thallium and toxaphene), the PT data does not support reduction of
the current PQL.
Out of these eight analytes, new or improved analytical methods are available for three
analytes (chlordane, l,2-dibromo-3-chloropropane and pentachlorophenol).
Exhibit ES.1: Analytical Feasibility Assessment Summary for Analytes with MCL
Equal to Current PQL
Analyte
Current
PQL (Mg/L)
MCL
(mq/l)
New or
Updated
Methods?
Qualitative
Recommendation
Chlordane
2
2
Yes
No change to current PQL
1,2-Dibromo-3-chloropropane
(DBCP)
0.2
0.2
Yes
No change to current PQL
Dioxin
0.00003
0.00003
No
No change to current PQL
Heptachlor
0.4
0.4
No
No change to current PQL
Heptachlor Epoxide
0.2
0.2
No
No change to current PQL
Pentachlorophenol
1
1
Yes
No change to current PQL
Thallium
2
2
No
No change to current PQL
Toxaphene
3
3
No
No change to current PQL
For the remaining eight analytes (carbofuran, cis-l,2-dichloroethylene, cyanide,
hexachlorocyclopentadiene, oxamyl, selenium, toluene and xylenes), the PQL is lower
than the MCL and hence, the MCL may be reduced (refer to Exhibit ES.2 for results of
the PQL analyses).
o Of the eight analytes, two analytes (cis-1, 2-dichloroethylene and toluene) have
PT data that support further reduction of the PQL.
o For these two analytes (cis-1,2-dichloroethylene and toluene), new or improved
analytical methods are available. However, it is not known if these new method(s)
are expected to improve analytical performance below the current PQL.
o For the remaining six analytes (carbofuran, cyanide, hexachlorocyclopentadiene,
oxamyl, selenium and xylenes), PT data does not support the reduction of the
current PQL.
o Out of these six analytes, new or improved analytical methods are available for
three analytes (cyanide, hexachlorocyclopentadiene and xylenes).
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Exhibit ES.2: Analytical Feasibility Assessment Summary for Analytes with MCL
Greater than the Current PQL
Analyte
Current
PQL
(mq/l)
MCL
(mq/l)
New or
Updated
Methods?
Qualitative
Recommendation
Carbofuran
7
40
No
No change to current
PQL
Cis-1,2-dichloroethylene
5
70
Yes
Reduction of current
PQL is supported
Cyanide
100
200
Yes, MDLs
lower
No change to current
PQL
Hexachlorocyclopentadiene
1
50
Yes
No change to current
PQL
Oxamyl (vydate)
20
200
No
No change to current
PQL
Selenium
10
50
No
No change to current
PQL
Toluene
5
1,000
Yes
Reduction of current
PQL is supported
Xylenes
5
10,000
Yes
No change to current
PQL
For those analytes with improved laboratory methods, the existence of new methods may not
directly translate to improved analytical performance, even with improved detection limits. It is
possible that only a small number of laboratories will use a new method, or it may take time for
the method to be utilized to its full effectiveness, i.e. if 75 percent or more laboratories cannot
meet the acceptance criteria using a certain analytical method, then the PQL cannot be lowered
any further.
Overall, the results show that for only two of the 16 analytes evaluated in this report, laboratory
performance data was sufficient to qualitatively conclude that the PQL can be lowered. For the
others, there was either no correlation or a correlation could not be made due to insufficient data.
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1 Introduction
The Safe Drinking Water Act (SDWA), as amended in 1996, requires the Environmental
Protection Agency (EPA) to review and revise, if appropriate, existing National Primary
Drinking Water Regulations (NPDWRs). Under the 1996 SDWA Amendments, EPA has
completed two comprehensive reviews of the existing NPDWRs: Six-Year Review 1 (completed
in July 2003) and Six-Year Review 2 (completed in March 2010). Under Six-Year Review 2,
EPA reviewed 71 NPDWRs and identified four chemical NPDWRs for revision.
As part of the second Six-Year Review, EPA developed a protocol document (USEPA, 2009a)
that describes the process and strategy EPA uses to review existing NPDWRs in order to meet its
statutory requirement. The protocol was based on the recommendations from the National
Drinking Water Advisory Council (NDWAC), internal Agency deliberations and discussions
with the diverse stakeholders involved in drinking water and its protection. As part of the review,
EPA reviewed the following key technical elements to make decisions regarding regulatory
changes: health effects assessments; technology assessments (analytical feasibility and treatment
technology); other regulatory revisions (e.g. monitoring and reporting); occurrence and exposure
analyses; and available economic information. This document specifically addresses the
analytical feasibility aspect of the Six-Year Review 3. Analytical feasibility assessment is one of
the key components of regulations review because the analytical feasibility may have been the
limiting factor in setting the Maximum Contaminant Level (MCL) for some of the existing
NPDWRs or because the health effects reviews may indicate a potential change in the Maximum
Contaminant Level Goal (MCLG). This document examines analytical method performance over
time by determining if the Practical Quantitation Levels (PQLs) may have changed since
promulgation. The PQL is defined as "the lowest achievable level of analytical quantitation
during routine laboratory operating conditions within specified limits of precision and accuracy"
(USEPA, 1985b) and is derived from the laboratory accreditation studies performed as part of
the drinking water laboratory certification program. Data from these studies was referred to as
Performance Evaluation (PE) data while the program was under EPA oversight until 1999 and as
Proficiency Testing (PT) data when the program was privatized with The NELAC Institute (TNI)
providing oversight.
Analytical method performance is also assessed by comparing the Method Detection Limits
(MDLs) of the analytical methods which were available at the time of promulgation to those of
the currently approved methods. The purpose was to determine if PQL changes based on the PT
data were also supported by the approval and availability of new/improved methods to the testing
laboratories. This analytical feasibility assessment is based on the recent analytical performance
data collected after Six-Year Review 2, where applicable. Efforts were also made to determine if
the analytical performance assessments based on the laboratory data are supported by improved
methods or revision of existing methods since the last review. The goal was to create a
comprehensive document that addresses all regulated chemical analytes for which data is
available.
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In this document, PQL assessments are presented for 16 regulated contaminants for which data
was available based on an initial review and analysis conducted under the Six-Year Review 3
Protocol. The results for the 16 regulated analytes are categorized into two subsets based on the
limitation of the PQL for setting the Maximum Contaminant Level (MCL) at the time of
promulgation: 1) analytes with MCL equal to the current PQL and thus the PQL is limiting and
2) analytes with MCL greater than the current PQL and thus it is technically feasible to reduce an
MCL.
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2 Background
2.1 SDWA Requirements for Analytical Methods
Section 1401(l)(C)(i) of SDWA (as amended in 1996); 42 U.S.C. § 300f(l)(C)(i), states that an
MCL for a national primary drinking water regulation is set "if, in the judgment of the
Administrator, it is economically and technologically feasible to ascertain the level of such
contaminant in water in public water systems." According to SDWA, NPDWRs include "criteria
and procedures to assure a supply of drinking water which dependably complies with such
maximum contaminant levels; including accepted methods of quality control and testing
procedures to insure compliance with such levels" [§1401(1)(D) of SDWA; 42 U.S.C. §
300f(l)(D)]. Except in certain circumstances, EPA is to set the MCL as close to the MCLG as is
feasible with the best available technologies (Section 1412 (b)(4)(B)) of SDWA. The MCLs for
several SDWA contaminants were set at levels higher than MCLGs due to the limits of the
analytical feasibility at that time. Since the promulgation of pre-1996 SDWA NPDWRs, newer
analytical methods and updated methods for measuring SDWA contaminants have been
approved. The approval of newer analytical techniques may have provided laboratories with the
analytical capability to measure some contaminants at lower levels. In addition, some
laboratories may have improved in their ability to measure at lower levels using the same
methods that were originally promulgated.
EPA evaluated the overall sensitivity of analytical methods when considering analytical methods
for the contaminants of interest. EPA has used two measures of analytical capability, the MDL
and the PQL.
The MDL is a measure of method sensitivity. The MDL is defined at 40 CFR Part 136
Appendix B as "the minimum concentration of a substance that can be reported with 99
percent confidence that the analyte concentration is greater than zero." MDLs can be
operator, method, laboratory and matrix-specific. Due to normal day-to-day and run-to-
run analytical variability, MDLs may not be reproducible within a laboratory or between
laboratories. The regulatory significance of the MDL is that EPA uses the MDL to
determine when a contaminant is considered to be detected and it can be used to calculate
a PQL for that contaminant.
The PQL is defined as "the lowest achievable level of analytical quantitation during
routine laboratory operating conditions within specified limits of precision and accuracy
(USEPA, 1985b)". The Agency has used the PQL to estimate or evaluate the minimum
concentration at which most laboratories can be expected to reliably measure a specific
chemical contaminant during day-to-day analyses of drinking water samples. The PQL is
a means of integrating information on the performance of the approved analytical methods
into the development of a drinking water regulation (USEPA, 1987). The PQL incorporates
the following (USEPA, 1985a; USEPA, 1987; 54 USEPA, 1989):
o Quantitation,
o Precision and bias,
o Normal operations of a laboratory, and
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o The fundamental need to have a sufficient number of laboratories available to
conduct compliance monitoring analyses.
In some cases, the quantitation level for a particular analyte may have been the limiting factor in the
determination of the MCL for that analyte. This could be especially true for contaminants with
MCLGs of zero. In addition, there are several SDWA contaminants with non-zero MCLGs that have
their MCL set at the PQL.
2.2 PQL Determination Methods for the SDWA Contaminants
EPA used two main approaches to determine PQLs for SDWA analytes. One approach (and the
preferred approach) used data from laboratory Performance Evaluaiton (PE studies, now called
PT or Proficiency Testing studies). Although the primary use of the PE/PT data was for EPA's
laboratory certification, the data was also used as a secondary data source for many years to
develop PQLs when the spike concentrations were in the appropriate concentration range.
In deriving a PQL from the laboratory performance data (contaminants spiked in reagent grade
water), EPA typically sets a fixed percentage, or 2 Sigma (two standard deviations), acceptance
criteria around the known concentration (or spike value) of the samples. While the acceptance
limits for inorganics typically range from 15 to 30 percent (40 CFR§141.23(k)(3)(ii)), the
acceptance limits for organics generally range from 20 to 50 percent (40 CFR §141.24(f)( 17)(i)
and 40 CFR§141.24(h)(19)(i). Several SDWA analytes have acceptance limits of 2 Sigma (two
standard deviations). The derivation of the PQL using PE/PT data involved determining the
concentration of an analyte at which 75 percent of the participating laboratories achieved results
within a specified range around the spike value or acceptance criteria.
In the absence of PE/PT data, the other approach that EPA used was the MDL multiplier method.
In this approach, the PQL was calculated by multiplying the EPA-derived MDL by a factor of 5
or 10. The MDL multiplier method was mostly used in the early years of rule development for
NPDWRs when sufficient WS data was not available. Once sufficient WS data became
available, most of the PQLs developed using the MDL multiplier were validated using WS data.
2.3 Operational Details of the PE/PT Programs
Performance Evaluation studies are no longer performed by EPA. In December 1999, the PT
program became privatized under the direction of the National Environmental Laboratory
Accreditation Conference (NELAC, or now, TheNELAC Institute [TNI]). PT data services under
TNI's program are provided by private companies that prepare and provide PT samples (spiked
at concentrations in accordance with TNI policies) to analytical laboratories as part of
maintaining laboratory accreditation. Approximately 10-12 such PT providers (e.g.,
Environmental Resource Associates (ERA)) exist nationwide. PT providers also compile the
results of the PT analyses for use by TNI.
A laboratory either passes or fails for each analyte based upon the Acceptance Limits (referred to
as Acceptance Criteria by TNI). The acceptance criteria adopted by TNI could be:
1. Percentage based (20 percent of the spiked, or true value),
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2. Standard deviation-based (± 2 standard deviations), or
3. Based on average and range of replicate analyses (radionuclides only).
The acceptance criteria for a contaminant may also change based on its concentration. While
more laboratories and more spiking concentrations were represented in the TNI PT data, fewer
analytes had data at, or below, their PQL. Further, TNI data was not separated by any analytical
methods.
Similar to the previous six-year reviews, the data was categorized into two subsets: 1) analytes
with an MCL equal to the current PQL, and thus the PQL is limiting; or 2) analytes with MCL
greater than the current PQL and thus it is technically feasible to reduce an MCL.
It is noted that the PT data obtained from the PT providers did not include a PQL, however, the
results reported from the laboratories was based on a TNI Proficiency Testing Reporting Limit
(PTRL). A PTRL is the lowest level acceptable result that could be obtained from the lowest
spike level for each analyte. Laboratories report any positive result down to the PTRL. It is
possible that in some cases (especially for analytes that exhibit low recovery), the PTRL may be
below the standard laboratory reporting limit. TNI PTRLs are provided as guidance to
laboratories analyzing TNI PT samples. At a minimum, the laboratory should use a method that
is sensitive enough to generate quantitative results at the PTRLs shown.
2.4 Efforts Made to Obtain PT Data
The following is a summary of the efforts made by EPA to obtain nationally representative PT
data from private firms that now provide PT services and/or directly from TNI. EPA contacted
seven PT providers to find out if they were willing to provide data for the Six-Year Review 3
along with a data request. Only basic information was requested as listed below:
Contaminant name being tested,
Analytical method being used (including EPA Methods and any newer methods),
Current MDL or MDL range,
PQL,
Concentration of PE sample,
Acceptance criteria, and
Pass/fail rates at different concentrations.
In the communication with all the PT providers, it was made very clear that EPA needed only
basic information and would not require the identity of any individual lab, etc. and would not
require the disclosure of what would be considered confidential business information (CBI).
Several attempts were made to contact and obtain data from seven PT providers. Out of the
seven PT providers, only two PT providers, Environmental Resources Associates, Inc. (ERA)
and Phenova responded and provided the information requested. The remaining five PT
providers either did not respond back to any communication from EPA, or responded that
although they were willing to provide data, time and budget constraints did not allow them to do
so; or responded that the information requested was CBI, and therefore, could not be released.
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3 Representativeness of Available PT Data
As of July 2014, there were seven TNI-accredited companies that provided PT services. Two of
these PT providers agreed to provide pass/fail rate data to EPA, while the other five were unable
or unwilling to provide the requested information. The Six-Year Review 2 report relied on data
from one PT provider. The additional data source in the current analysis removes some of the
uncertainties associated with using only one data source.
The following contaminant assessments are based on the available PT data from two sources but
obviously do not reflect all of the PT data generated throughout the country. There is no reason
to expect that the two sources of data are not representative of the larger pool of data, however,
since it is not known, it does provide an element of uncertainty. It is unknown if the data from
those PT providers who were not able to participate differs from data from those providers who
were able to participate. Also, because the pass/fail rates of the available data are reported
anonymously, it is not known how many labs or locations are represented or whether failure rates
tend to be influenced by certain labs. A qualitative comparison of the two data sources was
performed to analyze if the available data was adequate for analysis and if there was any bias in
the results between the two sources. The qualitative comparison between the two data sources is
presented in Exhibit 3.1.
Exhibit 3.1: Qualitative Comparison of Two Data Sources
SNo.
Contaminant
PT Provider 1
No. of data
points
PT Provider 1
% Data
Acceptable
PT Provider 2
No. of Data
Points
PT Provider 2
% Data
Acceptable
1
1,2-Dibromo-3-chloropropane
442
96%
NA
NA
2
Carbofuran
24
100%
718
97%
3
Chlordane
12
100%
858
96%
4
cis-1,2-Dichloroethylene
355
95%
2580
85%
5
Cyanide
468
89%
1066
92%
6
Dioxin
3
100%
NA
NA
7
Heptachlor
111
97%
1111
95%
8
Heptachlor Epoxide
112
96%
NA
NA
9
Hexachlorocyclopentadiene
141
94%
1030
95%
10
Oxamyl (vydate)
25
96%
708
95%
11
Pentachlorophenol
75
95%
837
95%
12
Selenium
958
93%
4523
95%
13
Thallium
814
91%
3725
95%
14
Toluene
355
97%
2636
97%
15
Toxaphene
13
100%
853
91%
16
Xylenes
354
93%
2644
93%
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As shown in Exhibit 3.1, for most of the contaminants except l,2-dibromo-3-chloropropane,
dioxin and heptachlor epoxide, the amount of data provided by PT Provider 1 is more than PT
Provider 2. However, a comparison of the percentage of data acceptable, i.e., the percent passing
rates for both the data sets shows that these values are very similar for both the data sets. Based
on this comparison, the data provided by the two PT providers was considered adequate for
performing the analysis per the Six-Year Review 3 protocol.
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4 Identification of Regulated Analytes for PQL Assessment
The Six-Year Review 1 analytical feasibility assessed whether the PQL value changed for 40 of
the 68 chemical NPDWRs. The Six-Year Review 2 analytical feasibility evaluated all regulated
analytes for which PT data were available. For the Six-Year Review 3, EPA prioritized 24 of the
68 analytes for review to determine if concentrations below the PTRL or PQL were routinely
measured. Based on an initial analysis of the PT data obtained from the PT providers, the number
of analytes for which PQL analysis would be performed was narrowed down to only 16 analytes.
Exhibit 4.1 summarizes the 16 analytes evaluated in the Six-Year Review 3, their range of
MDLs, current PTRL value, MCL and current PT acceptance criteria.
Exhibit 4.1: US EPA National Primary Drinking Water Standards and Analytical
Information
Analyte
CASRN
EPAMDL
or Range
(mq/l)
PTRL
(mq/l)
PQL
(mq/l)
MCL
(mq/l)
Acceptance Criteria
Benzo[a]pyrene
50-32-8
0.043 -0.52
0.02
0.2
0.2
Mean ± 2 Std Dev
Carbofuran
1563-66-2
0.01 -0.12
8.3
7
40
± 45%
cis-1,2-Dichloroethylene
156-59-2
0.0015-0.14
1.2
5
70
± 40% at< 10 ± 20% > 10
Cyanide
57-12-5
0.5-50
75
100
200
± 25%
1,2-Dibromo-3-chloropropane
(DBCP)
96-12-8
0.0016-
0.063
0.06
0.2
0.2
± 40%
Dioxin
1746-01-6
0.0000044
0.000011
0.00003
0.00003
Mean ± 2 Std Dev
Heptachlor
76-44-8
0.0015-0.34
0.11
0.4
0.4
± 45%
Heptachlor Epoxide
1024-57-3
0.0001 -
0.202
0.11
0.2
0.2
± 45%
Hexachlorocyclopentadiene
77-47-4
0.004 -0.16
0.49
1
50
Mean ± 2 Std Dev
Oxamyl (vydate)
23135-22-0
0.045 -0.86
11
20
200
Mean ± 2 Std Dev
Pentachlorophenol
87-86-5
0.021 -1.6
0.5
1
1
± 50%
Selenium
7782-49-2
1.0-2.0
8
10
50
± 20%
Thallium
7440-28-0
0.7 -1.0
1.4
2
2
± 30%
Toluene
108-88-3
0.01 -0.11
1.2
5
1000
± 40% at< 10 ± 20% > 10
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Analyte
EPAMDL
PTRL
PQL
MCL
Acceptance Criteria
CASRN
or Range
(mq/l)
(mq/l)
(mq/l)
(mq/l)
Toxaphene
0.13-1.0
1.1
3
3
± 45%
8001-35-2
Xylenes
0.01 -0.13
1.2
5
10000
± 40% at< 10 ± 20% > 10
1330-20-7
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5 Six-Year Review 3 Assessment Methodology
5.1 Data Available for PQL Assessments
The quantitative PTRL assessments are based on data from the two TNI-accredited PT providers
who were willing to share pass/fail testing data results with EPA. Exhibit 5.1 summarizes the
availability of Six-Year Review 1 PE data, Six-Year Review 2, Six-Year Review 3 PT data and
whether data is available at or below the PQL or PTRL for each analyte. Data available below
the PQL or PTRL indicates that technology or methodology improvements allow for an
increased range of chemical measurements. Improved measurement ability is an important
consideration to determine whether an analytical or regulatory value for a particular analyte may
be lowered. In comparison to the first and second Six-Year Reviews, where a total of 68 analytes
were evaluated, Six-Year Review3 evaluated 24 analytes, out of which the final PQL analysis
was performed for 16 analytes. The remaining eight analytes did not require further analysis
based on the Six-Year Review 3 protocol.
A review of new or revised EPA-approved drinking water methods was performed to evaluate
the analytical methods available between 2007 and 2014. The approval of new methods might
reflect an improvement in analytical performance and thus potential rationale for lowering
analytical or regulatory values for a particular compound. Section 6 contains a summary of
findings for each analyte including the currently applicable analytical methods.
Exhibit 5.1: Availability of Six-Year Review 1 PE Data and Six-Year Review 2 and
Six-Year Review 3 PT Data for Regulated Analytes
Analyte
CASRN
In Six-Year Review
1 Data
1996-2000
In Six-Year Review
2 Data (ERA)
2000-2007
In Six-Year Review
3 Data (Phenova
and ERA)
2008-2014
Acrylamide
79-06-1
No
No
Not reviewed
Alachlor
15972-60-8
Yes, some data <
PQL
Yes, no data < PQL
Not reviewed
Antimony
7440-36-0
Yes, some data <
PQL1
Yes, no data < PQL
Not reviewed
Arsenic
7440-38-2
Yes, some data <
PQL1
Yes, no data < PQL
Not reviewed
Atrazine
1912-24-9
Yes, some data <
PQL1
Yes, no data < PQL
Not reviewed
Barium
7440-39-3
Yes, some data <
PQL1
Yes, no data < PQL
Not reviewed
Benzene
71-43-2
Yes, some data <
PQL
Yes, some data <
PQL
Not reviewed
Benzo[a]pyrene
50-32-8
Yes, no data < PQL
Yes, no data < PQL
Yes3
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Analyte
CASRN
In Six-Year Review
1 Data
1996-2000
In Six-Year Review
2 Data (ERA)
2000-2007
In Six-Year Review
3 Data (Phenova
and ERA)
2008-2014
Beryllium
7440-41-7
Yes, some data <
PQL
Yes, no data < PQL
Not reviewed
Bromate
15541-45-4
Yes, some data <
PQL
Yes, some data <
PQL
Not reviewed
Cadmium
7440-43-9
Yes, no data < PQL
Yes, no data < PQL
Not reviewed
Carbofuran
1563-66-2
Yes, some data <
PQL
Yes, no data < PQL
Yes, no data < PQL
Carbon tetrachloride
56-23-5
Yes, some data <
PQL
Yes, some data <
PQL
Not reviewed
Chlordane
57-74-9
Yes, some data <
PQL
Yes, no data < PQL
Yes, no data < PQL
Chlorite
7758-19-2
Yes, but no PQL
Yes, but no PQL
Not reviewed
Chromium (total)
Cr III: 6065-83-1
Cr VI: 18540-29-9
Yes, no data < PQL
Yes, no data < PQL
Not reviewed
Copper
7440-50-8
Yes, some data <
PQL1
Yes, no data < PQL
Not reviewed
Cyanide (as free cyanide)
57-12-5
Yes, only one datum
= PQL; no data <
PQL
Yes, no data < PQL
Yes, no data < PQL
Dalapon
75-99-0
Yes, some data <
PQL; passing rates
below PQL could not
be calculated 2
Yes, no data < PQL
Not reviewed
1,2-Dibromo-3-chloropropane
(DBCP)
96-12-8
Yes, some data <
PQL
Yes, some data
-------
Analyte
CASRN
In Six-Year Review
1 Data
1996-2000
In Six-Year Review
2 Data (ERA)
2000-2007
In Six-Year Review
3 Data (Phenova
and ERA)
2008-2014
cis-1,2-Dichloroethylene
156-59-2
Yes, no data < PQL
Yes, some data <
PQL
Yes, some data <
PQL
trans-1,2-Dichloroethylene
156-60-5
Yes, no data < PQL
Yes, some data <
PQL
Yes3
Dichloromethane (Methylene
chloride)
75-09-2
Yes, no data < PQL
Yes, no data < PQL
Not reviewed
2,4-Dichlorophenoxyacetic
acid (2,4-D)
94-75-7
Yes, some data <
PQL
Yes, no data < PQL
Not reviewed
1,2-Dichloropropane
78-87-5
Yes, no data < PQL
Yes, some data <
PQL
Not reviewed
D i (2-eth y I h exy I) ad i pate
(DEHA)
103-23-1
Yes, some data <
PQL; passing rates
below PQL could not
be calculated 2
Yes, no data < PQL
Not reviewed
Di(2-ethylhexyl) phthalate
(DEHP)
117-81-7
Yes, some data <
PQL
Yes, no data < PQL
Yes3
Dinoseb
88-85-7
Yes, no data < PQL
Yes, no data < PQL
Not reviewed
Diquat
85-00-7
Yes, no data < PQL
Yes, no data < PQL
Not reviewed
Endothall
145-73-3
Yes, some data <
PQL; passing rates
below PQL could not
be calculated 2
Yes, no data < PQL
Yes3
Endrin
72-20-8
Yes, no data < PQL1
Yes, no data < PQL
Not reviewed
Epichlorohydrin
106-89-8
No
No
Not reviewed
Ethyl benzene
100-41-4
Yes, no data < PQL
Yes, some data <
PQL
Not reviewed
Ethylene dibromide (EDB)
106-93-4
Yes, no data < PQL
Yes, no data < PQL
Yes3
Fluoride
16984-48-8
Yes, some data <
PQL
Yes, no data < PQL
Not reviewed
Glyphosate
1071-83-6
Yes, no data < PQL
Yes, no data < PQL
Not reviewed
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Analyte
CASRN
In Six-Year Review
1 Data
1996-2000
In Six-Year Review
2 Data (ERA)
2000-2007
In Six-Year Review
3 Data (Phenova
and ERA)
2008-2014
Heptachlor
76-44-8
Yes, some data <
PQL
Yes, no data < PQL
Yes, some data <
PQL
Heptachlor epoxide
1024-57-3
Yes, some data <
PQL
Yes, no data < PQL
Yes, no data < PQL
Hexachlorobenzene
118-74-1
Yes, some data <
PQL
Yes, some data <
PQL
Yes3
Hexachlorocyclopentadiene
77-47-4
Yes, some data <
PQL
Yes, no data < PQL
Yes, some data <
PQL
Lead
7439-92-1
Yes, some data <
PQL1
Yes, no data < PQL
Not reviewed
Lindane
58-89-9
Yes, some data <
PQL1
Yes, no data < PQL
Not reviewed
Mercury (Inorganic)
7439-97-6
Yes, no data < PQL
Yes, no data < PQL
Not reviewed
Methoxychlor
72-43-5
Yes, some data <
PQL
Yes, no data < PQL
Not reviewed
Monochlorobenzene
(Chlorobenzene)
108-90-7
Yes, no data < PQL
Yes, some data <
PQL
Not reviewed
Nitrate (as N)
14797-55-8
Yes, no data < PQL
Yes, no data < PQL
Not reviewed
Nitrite (as N)
14797-65-0
Yes, some data <
PQL
Yes, no data < PQL
Not reviewed
Oxamyl (Vydate)
23135-22-0
Yes, some data <
PQL
Yes, no data < PQL
Yes, some data <
PQL
Pentachlorophenol
87-86-5
Yes, some data <
PQL
Yes, no data < PQL
Yes, no data < PQL
Picloram
1918-02-1
Yes, no data < PQL
Yes, no data < PQL
Not reviewed
Polychlorinated biphenyls
(PCBs) as Decachlorobiphenyl
(DCBP)
1336-36-3
Yes, some data <
PQL
Yes, no data < PQL
Yes3
Selenium
7782-49-2
Yes, some data <
PQL1
Yes, no data < PQL
Yes, no data < PQL
Simazine
122-34-9
Yes, some data <
PQL; passing rates
below PQL could not
be calculated 2
Yes, no data < PQL
Not reviewed
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Analyte
CASRN
In Six-Year Review
1 Data
1996-2000
In Six-Year Review
2 Data (ERA)
2000-2007
In Six-Year Review
3 Data (Phenova
and ERA)
2008-2014
Styrene
100-42-5
Yes, no data < PQL
Yes, some data <
PQL
Not reviewed
2,3,7,8-TCDD (Dioxin)
1746-01-6
No
Yes, no data < PQL;
only one spike level
Yes (data limited)
Tetrachloroethylene
127-18-4
Yes, no data < PQL
Yes, some data <
PQL
Not reviewed
Thallium
7440-28-0
Yes, some data <
PQL
Yes, no data < PQL
Yes, no data < PQL
Toluene
108-88-3
Yes, no data < PQL
Yes, some data <
PQL
Yes, some data <
PQL
Toxaphene
8001-35-2
Yes, some data <
PQL
Yes, no data < PQL
Yes, some data <
PQL
2,4,5-TP (Silvex)
93-72-1
Yes, some data <
PQL1
Yes, no data < PQL
Not reviewed
1,2,4-Trichlorobenzene
120-82-1
Yes, no data < PQL
Yes, some data <
PQL
Not reviewed
1,1,1-Trichloroethane
71-55-6
Yes, some data <
PQL
Yes, some data <
PQL
Not reviewed
1,1,2-Trichloroethane
79-00-5
Yes, no data < PQL
Yes, some data <
PQL
Yes3
Trichloroethylene
79-01-6
Yes, no data < PQL
Yes, some data <
PQL
Not reviewed
Vinyl chloride
75-01-4
Yes, no data < PQL
Yes, some data <
PQL
Not reviewed
Xylenes (total)
1330-20-7
Yes, no data < PQL
Yes, some data <
PQL
Yes, no data < PQL
Notes:
1 Means passing rates for Six-Year 1 data were calculated as these analytes were not evaluated in the March 2003
report, and acceptance criteria are percentage-based, not ± 2 Std Dev.
2 Passing rates for Six-Year 1 data at or below the PQL could not be calculated as these analytes were not evaluated
in the March 2003 report, acceptance criteria are ± Std Dev and available regression coefficients are not valid at or
below the PQL.
3 Initial data evaluation was performed for PQL analysis suitability and were not further considered for final PQL
analysis and summary.
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5.2 Data Assessment Methodology
The data obtained from the two PT providers was combined into one data set. A preliminary data
review was performed to assess the methods used for analysis and verify if the methods
correspond to the EPA approved analytical methods listed in the Federal Register (FR). Data
outliers including EPA Methods used for analyzing wastewater samples, etc., non-EPA approved
methods, etc., were eliminated. If the true concentration of the samples reported by the
laboratories met the acceptance criteria set forth in the FR, the samples were reported as
"acceptable". If the true concentration of the samples did not meet the acceptance criteria, the
samples were reported as "not acceptable". The acceptable data points were converted into
laboratory passing rates. A linear regression was plotted for each contaminant with laboratory
passing rates versus the true concentration of the sample. The PQL is set at the concentration
where 75 percent of the laboratories are predicted to meet acceptance criteria.
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6 Results of PQL Assessment
EPA used two very different approaches to assess improvements in laboratory analytical
performance over time: 1) evaluating data from the laboratory accreditation studies performed as
part of the drinking water laboratory certification program (PT data) and 2) comparing
information of the analytical methods available for compliance monitoring at the time of
promulgation to those available currently. For analytes with no new methods, analytical
performance was measured solely by PT data. For those analytes with new methods, analytical
performance was measured by PT data, but may be supported by lower detection limits (DLs)
from new methods. However, the existence of new methods with lower detection limits may not
directly translate to improved analytical performance. It is possible that only a small number of
laboratories will use a new method, or it may take time for the method to be utilized to its full
effectiveness. A passing rate of 75 percent was used as a basis for evaluation of the results of the
PQL assessment.
For each analyte, MDLs from EPA-approved methods were compared and a PQL/PTRL
assessment was presented by means of linear regression of the data obtained from the combined
PT data from both PT providers. Note that MDLs from proprietary methods (i.e., analytical
methods not developed by EPA) are not included in the MDL comparison, as they are not readily
available. Based on the data evaluation, a qualitative conclusion is drawn by presenting a
recommendation of whether a PQL might be reduced. The discussion includes an indication of
how the true concentrations relate to the PQL/PTRL and how the PT data may or may not
suggest potential changes to the PQL.
The results for the regulated analytes are broken down into two categories based on the
limitation of the PQL for setting MCL at the time of promulgation: 1) analytes with MCL equal
to the current PQL, and thus the PQL is limiting; or 2) analytes with MCL greater than the
current PQL and therefore it is technically feasible to reduce an MCL. PQL assessments for these
analytes can indicate the potential for MCL reduction beyond the current PQL. The PQL
assessments were made and are presented in this report for a total of 16 analytes.
Using this framework, the following sub-categories are used to summarize the results of PQL
analysis. These categorizations were made based on a visual inspection of the regressions. In
some cases, even though the regression line was above the 75 percent passing rate, several
factors, including poor performance above the PQL or lack of data below the PQL led to a
conclusion that perhaps the PQL should not be reduced. In addition, consideration was given to
recent laboratory performance as indicated by the data provided by the PT providers. For
example, if the older Six-Year Review 1 data indicated that the PQL should not be reduced, and
if the more recent data indicated better performance, this was a factor in making the overall
determination as to whether or not a PQL could be reduced.
1. Analytes with an MCL equal to the current PQL, and therefore the PQL is limiting - The
outcome of this categorization would be summarized as one of the following:
a. PQL assessment supports reduction of the current PQL,
b. PQL assessment may support reduction of the current PQL, or
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c. PQL assessment does not support reduction of the current PQL, or data is
inconclusive or insufficient to reach a conclusion.
2. Analytes with an MCL greater than the current PQL and thus it is technically feasible to
reduce an MCL - the outcome of this categorization would be summarized as one of the
following:
a. PQL assessment supports reduction of the current PQL,
b. PQL assessment may support reduction of the current PQL, or
c. PQL assessment does not support reduction of the current PQL, or data is
inconclusive or insufficient to reach a conclusion.
Note that the qualitative conclusions presented in this report are not necessarily identical to the
conclusions that were documented in the previous six-year reviews' reports. Rather, a new
assessment is made herein considering the advantages and disadvantages of the PQL concept, the
availability of PT data in the vicinity of and/or below the PQL, and outliers. The qualitative
conclusions are based primarily on data that are in the vicinity of and/or below the PQL.
6.1 Category 1: Analytes with MCL Equal to the Current PQL and Thus the PQL is
Limiting
A total of eight analytes have an MCL that is set at the PQL. As a result, a PQL assessment is
required to determine whether an MCL might be lowered in the future. These eight analytes can
be further categorized into the three groups mentioned in Section 6 depending on whether or not
the PT assessments support the reduction of the current PQL.
6.1.1 PQL Assessment Supports Reduction of the Current PQL
None of the analytes under consideration fall under this category.
6.1.2 PQL Assessment May Supports Reduction of the Current PQL
None of the analytes under consideration fall under this category.
6.1.3 PQL Assessment Does Not Support Reduction of the Current PQL or Data is
Insufficient to Reach a Conclusion
All the eight analytes as mentioned in Section 6.1 have an existing PQL equal to the MCL and
their PE/PT data indicate that the PQL should not be lowered or their PE/PT data are insufficient
to reach a conclusion.
6.1.3.1 Chlordane
6.1.3.1.1 Results of the Method Comparison
Exhibit 6.1 summarizes the MDLs for chlordane as documented in EPA-developed analytical
methods. One new analytical method, EPA 525.3 (USEPA, 2012), was approved for the analysis
of chlordane in drinking water samples during the years 2008-2014. The MDL for chlordane by
EPA 525.3 is similar to the MDL of EPA 508 and 508.1, but lower than the MDL of EPA 505
and 525.2.
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Exhibit 6.1: Analytical Methods for Chlordane
EPA Methods
Approved For
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of Drinking
Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
EPA 505
Microextraction (ME) and Gas Chromatography (GC)
0.141
EPA 508
GC with Electron Capture Detector (ECD)
0.00151
EPA 508.1
Liquid-Solid Extraction (LSE) and Electron Capture Gas
Chromatography (ECGC)
0.001 - 0.004
EPA 525.2
LSE and Capillary Column Gas Chromatography
(CCGC)/Mass Spectroscopy (MS)
0.05 - 0.222
EPA 525.3*
Solid-Phase Extraction (SPE)/GC/MS
0.002
Notes:
* New approved analytical methods since last Six-Year Review.
1 MDL range for chlordane includes a-chlordane and y-chlordane.
2 MDL range for chlordane includes a-chlordane, y-chlordane and trans-nonachlor.
Regulatory DLs for organic compounds are listed at 40 CFR 141.24(h)(18).
Acceptance Criteria for organic compounds are listed at 40 CFR 141.24(h)(19)(i)(B).
MCL = 2.0 |jg/L
Current PQL = 2.0 |jg/L
DL = 0.2 |jg/L
Acceptance Criteria = ± 45%
6.1.3.1.2 Results of the PQL Analysis
The current PQL for chlordane is 2.0 |ig/L while the PTRL is 1.1 |ig/L. The data obtained from
the PT providers is summarized in Exhibit 6.2, along with a regression analysis. The entire data
obtained from the PT providers is based on using EPA Methods 505, 508, 508.1 and 525.2, as
listed in Exhibit 6.1. As shown in Exhibit 6.2, none of the data is below the current PQL of 2.0
|ig/L or below the PTRL of 1.1 |ig/L. The passing rate for all the data is above 75 percent.
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Exhibit 6.2: Evaluation of PT Data - Chlordane
100
90
80
txo
c
(S 70
Q-
(/)
Q)
£ 60 -
(D
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-Q
5 50
o
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40
30
20
0 2 4 6 8 10 12 14 16 18 20
Concentration of Sample (|ig/L)
A All Data PTRL PQL
6.1.3.1.3 Conclusions for Chlordane
Based on plotting the sample concentrations and the percent passing rate, it was observed that the
regression does not show much correlation between the two. Given the variable laboratory
passing rates for the data sets and the lack of data below the current PQL of 2.0 |ig/L, it may not
be appropriate to recommend lowering of the PQL. Compared to the previous six-year analysis,
one new method, i.e., EPA 525.3 was approved in February 2012. However, the data obtained
from the PT providers does not include results from this new method. Therefore, it is unknown
whether this method is expected to improve analytical performance below the current PQL (and
hence suggest possible reduction of the PQL).
6.1.3.2 l,2-Dibromo-3-Chloropropane (DBCP)
6.1.3.2.1 Results of the Method Comparison
Exhibit 6.3 summarizes the MDLs for l,2-dibromo-3-chloropropane (DBCP) as documented in
EPA-developed analytical methods. One new analytical method, EPA Method 524.3 (USEPA,
2009b), was approved for the analysis of DBCP in drinking water samples during the years
1 .
A AAAft A AA-A
1 aA
AM AAA AA A A
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1 I"
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i i i
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2008-2014. The low end of the MDL range for DBCP by EPA Method 524.3 is lower than the
MDL of EPA Methods 508 and 508.1, but higher than the MDL of EPA Method 551.1.
Exhibit 6.3: Analytical Methods for DBCP
EPA Methods
Approved for the
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of
Drinking Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
504.1
ME and GC
0.01
524.2
CCGC/MS
0.05 - 0.26
524.3*
Purge & Trap/CCGC/MS
0.0010- 0.063
551.1
LLE and GC with ECD
0.006 - 0.009
Notes:
* New approved analytical methods since last Six-Year Review.
Regulatory DLs for organic compounds are listed at 40 CFR 141.23(a) 4(l).
Acceptance Criteria for organic compounds are listed at 40 CFR 141.23(k)(3)(ii).
MCL = 0.2 |jg/L
Current PQL = 0.2 |jg/L
DL = 0.02 |jg/L
Acceptance Criteria = ± 40%
6.1.3.2.2 Results of the PQL Analysis
The current PQL for DBCP is 0.2 |ig/L while the PTRL is 0.06 |ig/L. The data obtained from the
PT providers is summarized in Exhibit 6.4, along with a regression analysis. Approximately 2
percent data obtained from the PT providers is based on the new EPA Method 524.3 while the
remaining 98 percent data is based on the existing EPA Methods 504.1, 524.2 and 551.1, as
listed in Exhibit 6.3. None of the data are below the current PQL of 0.2 |ig/L or below the PTRL
of 0.06 |ig/L. The passing rate for all the available data is at or above 75 percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-5
December 2016
-------
Exhibit 6.4: Evaluation of PT Data - DBCP
100
95
90
85
"17!
\A
ID
80
if)
OJ
O 75
i
o
"g 70
o
S? 65
60
55
50
0 0.5 1 1.5 2 2.5
Concentration of Sample (jig/L)
* Data Below 10 ug/L -PTRL PQL
6.1.3.2.3 Conclusions for DBCP
Given lack of data below the current PQL of 0.2 |ig/L, it may not be appropriate to recommend
lowering of the PQL. One new analytical method, EPA Method 524.3, has been approved since
2007, but since adequate data is not available using the new method, it is unknown whether this
is expected to improve analytical performance below the current PQL (and hence suggest
possible reduction of the PQL).
6.1.3.3 Dioxin
6.1.3.3.1 Results of the Method Comparison
Exhibit 6.5 summarizes the MDL for dioxin as documented in EPA-developed analytical
methods. No updated or new analytical methods have been approved for the analysis of dioxin in
drinking water samples during the years 2008-2014.
i :
1 i
A .
* A
A
A
j i
75% Passing
¦ i
Acceptance
1
i i
Criteria = ± 40%
Analytical Feasibility Support Document for
the Third Six-Year Review
6-6
December 2016
-------
Exhibit 6.5: Analytical Methods for Dioxin
EPA Methods
Approved for the
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of
Drinking Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
1613
Isotope Dilution High Resolution GC (HRGC)/High
Resolution MS (HRMS)
0.0000044
Notes:
Regulatory DLs for organic compounds are listed at 40 CFR 141.24(h)(18).
Acceptance Criteria for organic compounds are listed at 40 CFR 141.24(h)(19)(i)(B).
MCL = 0.00003 |jg/L
Current PQL = 0.00003 pg/L
DL = 0.000005 |jg/L
Acceptance Criteria = Mean ± 2 Std Dev
6.1.3.3.2 Results of the PQL Analysis
The current PQL for dioxin is 0.00003 |ig/L while the PTRL is 0.000011 |ig/L. The data
obtained from the PT providers is summarized in Exhibit 6.6, along with a regression analysis.
Not enough data was available to produce a regression that could be used for PQL analysis.
Exhibit 6.6: Evaluation of PT Data - Dioxin
100
95
90
85
-------
6.1.3.3.3 Conclusions for Dioxin
Given the lack of data for dioxin, it is not appropriate to make any recommendations regarding
the PQL. No new or revised methods that may be expected to improve analytical performance
below the current PQL (and hence suggest possible reduction of the PQL).
6.1.3.4 Heptachlor
6.1.3.4.1 Results of the Method Comparison
Exhibit 6.7 summarizes the MDLs for heptachlor as documented in EPA-developed analytical
methods. One new analytical method, EPA Method 525.3 (USEPA, 2012), was approved for the
analysis of heptachlor in drinking water samples during the years 2008-2014. The MDL for the
new EPA Method 525.3 is similar to the MDLs for other existing EPA Methods.
Exhibit 6.7: Analytical Methods for Heptachlor
EPA Methods
Approved for the
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of
Drinking Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
505
ME and GC
0.003
508
GC/ECD
0.0015
508.1
LSE and ECGC
0.005
525.2
LSE and CCGC/MS
0.059-0.15
525.3*
SPE and CCGC/MS
0.0032 - 0.34
551.1
LLE/GC w/ ECD
0.002 - 0.081
Notes:
* New approved analytical methods since last Six-Year Review.
Regulatory DLs for organic compounds are listed at 40 CFR 141.24(h)(18).
Acceptance Criteria for organic compounds are listed at 40 CFR 141.24(h)(19)(i)(B).
MCL = 0.4 |jg/L
Current PQL = 0.4 |jg/L
DL = 0.04 |jg/L
Acceptance Criteria = ± 45%
6.1.3.4.2 Results of the PQL Analysis
The current PQL for heptachlor is 0.4 |ig/L while the PTRL is 0.11 |ig/L. The data obtained from
the PT providers is summarized in Exhibit 6.8, along with a regression analysis. The entire data
obtained from the PT providers is based on using EPA Methods 505, 508, 508.1, 525.2 and
551.1, as listed in Exhibit 6.7. Two of the data points are below the current PQL of 0.4 |ig/L and
of those two, both are at or below the PTRL of 0.11 |ig/L. Except for one point, the passing rate
for all the data is at or above 75 percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-8
December 2016
-------
Exhibit 6.8: Evaluation of PT Data - Heptachlor
100
95
90
85
'S
to
ID
80
tO
.2
O 75
n
k.
O
"g 70
o
S? 65
60
55
50
0 0.5 1 1.5 2 2.5 3
Concentration of Sample (jig/L)
* All Data - PTRL PQL
6.1.3.4.3 Conclusions for Heptachlor
Given limited data below the current PQL of 0.4 |ig/L, it may not be appropriate to recommend
lowering of the PQL for heptachlor. One new analytical method has been approved since 2007,
but since the data provided by the PT providers does not include results from the new method, it
is unknown whether this is expected to improve analytical performance below the current PQL
(and hence suggest possible reduction of the PQL).
6.1.3.5 Heptachlor Epoxide
6.1.3.5.1 Results of the Method Comparison
Exhibit 6.9 summarizes the MDLs for heptachlor epoxide as documented in EPA-developed
analytical methods. One new analytical method, EPA Method 525.3 (USEPA, 2012), was
approved for the analysis of heptachlor epoxide in drinking water samples during the years 2008-
2014. The MDL for the new EPA Method 525.3 is similar to the MDLs for other existing EPA
Methods listed in Exhibit 6.9.
t 1
1 ! - A- -
1
1
1
1
1
¦ A
1
1
1
1
A A
A
A
A
A A
A A
A A
A
A
A A
A
A
75% Passing
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Acceptance Criteria
= ±45%
A
Analytical Feasibility Support Document for
the Third Six-Year Review
6-9
December 2016
-------
Exhibit 6.9: Analytical Methods for Heptachlor Epoxide
EPA Methods
Approved for the
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of Drinking
Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
EPA 505
ME and GC
0.004
EPA 508
GC with ECD
0.015
EPA 508.1
LSE and ECGC
0.0001
EPA 525.2
LSE and CCGC/MS
0.048-0.13
EPA 525.3*
SPE and CCGC/MS
0.0026
EPA 551.1
LLE and GC with ECD
0.002 - 0.202
Notes:
* New approved analytical methods since last Six-Year Review (USEPA, 2012).
Regulatory DLs for semi-volatile organic compounds are listed at 40 CFR 141.24(h)(18).
Acceptance Criteria for organic compounds are listed at 40 CFR 141.24(h)(19)(i)(B).
MCL = 0.2 |jg/L
Current PQL = 0.2 |jg/L
DL = 0.02 |jg/L
Acceptance Criteria = ± 45%
6.1.3.5.2 Results of the PQL Analysis
The current PQL for heptachlor epoxide is 0.2 |ig/L while the PTRL is 0.11 |ig/L. The data
obtained from the PT providers is limited and is summarized in Exhibit 6.10, along with a
regression analysis. The entire data obtained from the PT providers is based on using EPA
Methods 505, 508, 508.1, 525.2 and 551.1, as listed in Exhibit 6.9, except the new EPA Method
525.3. As shown in Exhibit 6.10, none of the data is below the current PQL of 0.2 |ig/L or below
the PTRL of 0.11 |ig/L. Except one data point, the passing rate for the entire data set is above 75
percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-10
December 2016
-------
Exhibit 6.10: Evaluation of PT Data - Heptachlor Epoxide
100
95
90
85
80
75
70
65
60
55
50
A *
A A
Acceptance
A Criteria = ±45%
75% Passing Rate
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Concentration of Sample (|ig/L)
5.0
A All Data
PTRL - - - - PQL
6.1.3.5.3 Conclusions for Heptachlor Epoxide
Given the limited data available for analysis and the lack of data below the current PQL of 0.2
|ig/L, it may not be appropriate to recommend lowering the PQL. One new analytical method has
been approved since 2007, but since the data provided by the PT providers does not include
results from the new method, it is unknown whether this method is expected to improve
analytical performance below the current PQL (and hence suggest possible reduction of the
PQL).
6.1.3.6 Pentachlorophenol
6.1.3.6.1 Results of the Method Comparison
Exhibit 6.11 summarizes the MDLs for pentachlorophenol as documented in EPA-developed
analytical methods. One new analytical method, EPA Method 525.3 (USEPA, 2012), was
approved for the analysis of pentachlorophenol in drinking water samples during the years 2008-
2014. The MDL for the new EPA Method 525.3 is the range of MDLs for other existing EPA
Methods listed in Exhibit 6.11.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-11
December 2016
-------
Exhibit 6.11: Analytical Methods for Pentachlorophenol
EPA Methods
Approved for the
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of
Drinking Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
515.1
GC with ECD
0.032
515.2
LSE and GC with ECD
0.16
515.3
LLE, Derivatization and GC with ECD
0.021 - 0.085
515.4
Liquid-Liquid ME, Derivatization and Fast GC with
ECD
0.014-0.084
525.2
LSE and CCGC/MS
0.72-1.0
525.3*
SPE and CCGC/MS
0.047 - 0.069
528
SPE and CCGC/MS
0.081 -0.25
555
High Pressure Liquid Chromatography (HPLC) with
Photodiode Array Ultraviolet Detector
0.15-1.6
Notes:
* New approved analytical methods since last Six-Year Review (USEPA, 2012).
Regulatory DLs for organic compounds are listed at 40 CFR 141.24(h)(18).
Acceptance Criteria for organic compounds are listed at 141.24(h)(19)(i)(B).
MCL = 1.0 |jg/L
Current PQL = 1.0 |jg/L
DL = 0.04 |jg/L
Acceptance Criteria = ± 50%
6.1.3.6.2 Results of the PQL Analysis
The current PQL for pentachlorophenol is 1.0 |ig/L while the PTRL is 0.5 |ig/L. The data
obtained from the PT providers is summarized in Exhibit 6.12, along with a regression analysis.
The entire data obtained from the PT providers is based on using EPA Methods listed in Exhibit
6.11, except the new EPA Method 525.3. None of the data is below the current PQL of 1.0 |ig/L
or below the PTRL of 0.5 |ig/L. Except for four points, the passing rate for all the data is at or
above 75 percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-12
December 2016
-------
Exhibit 6.12: Evaluation of PT Data - Pentachlorophenol
A 1
A ~
iA
~
PTRL = 0.5 |jg/L
¦ PQL =1.0 |jg/L
A AA
75% Passing Rate
A Acceptance
Criteria = ±50%
0 10 20 30 40 50 60 70 80 90 100
Concentration of Sample (|ig/L)
A All Data PTRL - - - - PQL
6.1.3.6.3 Conclusions for Pentachlorophenol
Given lack of data below the current PQL of 1.0 |ig/L, it may not be appropriate to recommend
lowering of the PQL. One new analytical method has been approved since 2007, but since the
data provided by the PT providers does not include results from the new method, it is unknown
whether this is expected to improve analytical performance below the current PQL (and hence
suggest possible reduction of the PQL).
6.1.3.7 Thallium
6.1.3. 7.1 Results of the Method Comparison
Exhibit 6.13 summarizes the MDLs for thallium as documented in EPA-developed analytical
methods. No updated or new analytical methods have been approved for the analysis of dioxin in
drinking water samples during the years 2008-2014. The MDLs for some of the approved EPA
methods are not known.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-13
December 2016
-------
Exhibit 6.13: Analytical Methods for Thallium
EPA Methods
Approved for the
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of
Drinking Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
EPA 200.7
Inductively Coupled Plasma (ICP)-Atomic Emission
Spectrometry
No MDL
EPA 200.8
ICP with MS
0.3
EPA 200.9
Stabilized Temperature Graphite Furnace Atomic
Absorption
1.0
Notes:
Regulatory DLs for inorganic compounds are listed at 40 CFR 141.23(a)(4)(i).
Acceptance Criteria for inorganic compounds are listed at 40 CFR 141.23(k)(3)(ii).
MCL = 2.0 |jg/L
Current PQL = 2.0 |jg/L
DL = 0.3-1.0 |jg/L
Acceptance Criteria = ± 30%
6.1.3.7.2 Results of the PQL Analysis
The current PQL for thallium is 2.0 |ig/L while the PTRL is 1.4 |ig/L. The data obtained from
the PT providers is summarized in Exhibit 6.14, along with a regression analysis. Approximately
95 percent data obtained from the PT providers is based on EPA Methods 200.7 (14 percent),
200.8 (61 percent) and 200.9 (20 percent) while the remaining 5 percent data is based on
Standard Methods SM3113 B, SM3120, SM3125, as listed in Exhibit 6.13. As shown in
Exhibit 6.14, none of the data is below the current PQL of 2.0 |ig/L or below the PTRL of 1.4
|ig/L. Except one point, the passing rate for all the data is above 75 percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-14
December 2016
-------
Exhibit 6.14: Evaluation of PT Data - Thallium
W>
E
O
ro
i
o
-Q
_i
H-
O
100
95
90
85
80
75
70
65
60
55
50
m x m A AM A A
A A / A ^ A ^ *^A ^
A A ~ iV^ ^
» ' A A A K A
A A A * *
A
A A
Acceptance
Criteria = ±30%
3 4 5 6 7
Concentration of Sample (|ig/L)
75% Passing Rate
10
A All Data PTRL - - - - PQL
6.1.3. 7.3 Conclusions for Thallium
Given the lack of data below the current PQL of 2.0 |ig/L, it may not be appropriate to
recommend lowering of the PQL. No new or revised methods that may be expected to improve
analytical performance below the current PQL (and hence suggest possible reduction of the
PQL) have been approved since 2007.
6.1.3.8 Toxaphene
6.1.3.8.1 Results of the Method Comparison
Exhibit 6.15 summarizes the MDLs for toxaphene as documented in EPA-developed analytical
methods. One new analytical method, EPA Method 525.3 (USEPA, 2012), was approved for the
analysis of toxaphene in drinking water samples during the years 2008-2014. The MDLs for
some of the methods are not known. The MDL for the new EPA Method 525.3 is in between the
range of the MDLs for the other existing EPA Methods.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-15
December 2016
-------
Exhibit 6.15: Analytical Methods for Toxaphene
EPA Methods
Approved for the
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of Drinking
Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
EPA 505
ME and GC
1.0
EPA 508
GC with ECD
Not given
EPA 508.1
LSE and ECGC
0.13
EPA 525.2
LSE and CCGC/MS
1.0-1.7
EPA 525.3*
SPE and CCGC/MS
0.32
Notes:
* New approved analytical methods since last Six-Year Review (USEPA, 2012).
Regulatory DLs for organic compounds are listed at 40 CFR 141.24(h)(18).
Acceptance Criteria for organic compounds are listed at 40 CFR 141.24(h)(19)(i)(B).
MCL = 3.0 |jg/L
Current PQL = 3.0 |jg/L
DL = 1.0 |jg/L
Acceptance Criteria = ± 45%
6.1.3.8.2 Results of the PQL Analysis
The current PQL for toxaphene is 3.0 |ig/L while the PTRL is 1.1 |ig/L. The data obtained from
the PT providers is summarized in Exhibit 6.16, along with a regression analysis. The entire data
obtained from the PT providers is based on using EPA Methods 505, 508, 508.1 and 525.2, as
listed in Exhibit 6.15. As shown in Exhibit 6.16, except for one data point which is below the
current PQL of 3.0 |ig/L and above the PTRL of 1.1 |ig/L, the rest of the data is above the
current PQL of 3.0 |ig/L and PTRL of 1.1 |ig/L. Except for a few data points, the passing rate for
all the data is above 75 percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-16
December 2016
-------
Exhibit 6.16: Evaluation of PT Data - Toxaphene
100
90
80
75% Passing Rate
70
60
Acceptance
Criteria = ±45%
50
40
30
20
0
2
4
6
8
10
12
14
16
18
20
Concentration of Sample (|ig/L)
A All Data PTRL - - - - PQL
6.1.3.8.3 Conclusions for Toxaphene
As shown in Exhibit 6.16, only one data point is below the current PQL of 3.0 |ig/L with a
passing rate of greater than 75 percent. Although most of the data is above the PQL with high
laboratory passing rates (above 75 percent), five data points failed the acceptance criteria. Given
the lack of adequate data points below the PQL and some failure rates at the current PQL, it may
not be appropriate to recommend lowering the PQL. One new analytical method has been
approved since 2007, but since adequate data is not available using the new method, it is
unknown whether this is expected to improve analytical performance below the current PQL
(and hence suggest possible reduction of the PQL).
6.2 Analytes with MCL Greater Than the Current PQL and Thus It is Technically
Feasible to Reduce an MCL
The analytes in this category have an existing PQL that is less than the MCL. If new health
information were to become available for any of these analytes, causing EPA to consider
reducing the MCL, the existing PQL would not hinder reduction of the MCL (to the level of the
current PQL). Eight analytes fit into this category. These eight analytes can be further
categorized into the two groups mentioned in Section 6.0 depending on whether or not the PE/PT
assessments support the further reduction of the current PQL.
Analytical Feasibility Support Document for 6-17 December 2016
the Third Six-Year Review
-------
6.2.1 PQL Assessment Supports Reduction of the Current PQL
Of the eight analytes mentioned above, two analytes have an existing PQL that is less than the
MCL and their PE/PT data suggest that the PQL could be lower.
6.2.1.1 cis-l,2-Dichloroethylene
6.2.1.1.1 Results of the Method Comparison
Exhibit 6.17 summarizes the MDLs for cis-l,2-dichloroethlyene as documented in EPA-
developed analytical methods. Two new analytical methods, EPA Method 524.3 USEPA, 2009b)
and EPA Method 524.4 (USEPA, 2013), were approved for the analysis of cis-1,2-
dichloroethylene in drinking water samples during the years 2008-2014. The MDLs for the two
new methods are within the range of MDLs for the other existing EPA Methods and are lower
than the current PQL.
Exhibit 6.17: Analytical Methods for cis-1,2-dichloroethylene
EPA Methods
Approved for the
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of
Drinking Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
EPA 502.2
CCGC with Photoionization and Electrolytic
Conductivity Detectors (ELCD)
0.01 -0.05
EPA 524.2
CCGC/Mass Spectrometry (MS)
0.06-0.12
EPA 524.3*
CCGC/MS
0.042
EPA 524.4*
GC/MS Using Nitrogen Purge Gas
0.083
Notes:
* New approved analytical methods since the last Six-Year Review (USEPA, 2009b and USEPA, 2013).
Regulatory DLs for organic compounds are listed at 40 CFR 141.24(k)(17)(ii)(C).
Acceptance Criteria for organic compounds are listed at 141.24(f)(17)(i) and also available at
http://www.nelac-institute.org/docs/pt/DW FOPT 2012 01 03.pdf.
MCL = 70 |jg/L
Current PQL = 5.0 |jg/L
DL = N/A
Acceptance Criteria = ± 40% at <10 |jg/L or ± 20% at >10 |jg/L
6.2.1.1.2 Results of the PQL Analysis
The current PQL for cis-l,2-dichloroethylene is 5.0 |ig/L while the PTRL is 1.2 |ig/L. The data
obtained from the PT providers is summarized in Exhibit 6.18, along with a regression analysis.
Approximately 96 percent data obtained from the PT providers is based on EPA Methods 502.2
and 524.2, while the remaining 4 percent data is based on the new EPA Method 524.3, as listed
in Exhibit 6.17. Since the acceptance criteria is ±40 percent at spike concentrations below 10
|ig/L and ±20 percent at or above 10 |ig/L, the data is regressed as two independent populations.
As shown in Exhibit 6.18, several data points are below the current PQL of 5.0 |ig/L. However,
none of the data is below the PTRL of 1.2 |ig/L. Except for two points, all the passing rates are
above 75 percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-18
December 2016
-------
Exhibit 6.18: Evaluation of PT Data - cis-1,2-Dichloroethylene
100
90
80
75% Passing Rate
70
1.2 (Jg/L PTRL
Acceptance
Criteria =±40%
Acceptance
Criteria =±20%
60
5 |Jg/L PQL
50
10 |_ig/LAcceptance
Criteria Boundary
40
0
10
20
30
40
50
Concentration of Sample (|ig/L)
A Data Below 10 ug/L ¦ Data Above 10 ug/L PTRL - - - - PQL
6.2.1.1.3 Conclusions for cis-l,2-dichloroethylene
The high laboratory passing rates (above 75%) at concentrations below the current PQL of 5.0
|ig/L suggest that the PQL could be lowered using the current methods. Two new analytical
methods have been approved since 2007. However, only 4 percent of the data provided by the PT
providers represents data from one new method EPA 524.3, out of which only three data points
are below the current PQL. Due to lack of sufficient data from the new method, it is unknown
whether this method is expected to improve analytical performance below the current PQL.
6.2.1.2 Toluene
6.2.1.2.1 Results of the Method Comparison
Exhibit 6.19 summarizes the MDLs for toluene as documented in EPA-developed analytical
methods. Two new analytical methods, EPA Method 524.3 (USEPA, 2009b) and EPA Method
524.4 (USEPA, 2013), were approved for the analysis of toluene in drinking water samples
during the years 2008-2014. The MDL for the new EPA Method 524.4 is not known. The MDL
for the new EPA Method 524.3 is in the range of the MDL for EPA Method 524.2 and slightly
higher than the MDL for EPA Method 502.2.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-19
December 2016
-------
Exhibit 6.19: Analytical Methods for Toluene
EPA Methods
Approved for
the Analysis
of Drinking
Water
EPA Methods Approved for the Analysis of Drinking
Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
EPA 502.2
Purge and Trap CCGC with Photoionization and ECDs in
Series
0.01 -0.02
EPA 524.2
CCGC/MS
0.08-0.11
EPA 524.3*
CCGC/MS
0.024
EPA 524.4*
GC/MS using Nitrogen Purge Gas
No MDL
Notes:
* New approved analytical methods since the last Six-Year Review (USEPA, 2009b, USEPA, 2013).
Regulatory DLs for volatile organic compounds are listed at 141.24(k)(17)(ii)(C).
Acceptance Criteria for toluene is listed at 40 CFR 141.24(f)(17)(i).
http://www.nelac-institute.org/docs/pt/DW FOPT 2012 01 03.pdf.
MCL = 1,000 |jg/L
Current PQL = 5.0 |jg/L
DL = N/A
Acceptance Criteria = ± 40% at < 10 |jg/L or± 20% >10 |jg/L
6.2.1.2.2 Results of the PQL Analysis
The current PQL for toluene is 5.0 |ig/L while the PTRL is 1.2 |ig/L. The data obtained from the
PT providers is summarized in Exhibit 6.20, along with a regression analysis. Approximately 96
percent data obtained from the PT providers is based on EPA Methods listed in Exhibit 6.19 and
excluding the new EPA Methods while the remaining 4 percent data is based on the new EPA
Methods 524.3 and 524.4, as listed in Exhibit 22. Since the acceptance criteria is ±40 percent at
spike concentrations below 10 |ig/L and ± 20 percent at or above 10 |ig/L, the data is regressed
as two independent populations. As shown in Exhibit 6.20, several data points are below the
current PQL of 5.0 |ig/L. However, none of the data is below the PTRL of 1.2 |ig/L. Except for
one point, all the passing rates are above 75 percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-20
December 2016
-------
Exhibit 6.20: Evaluation of PT Data - Toluene
100
1 A a
I *
¦
90
1
i
1 A
.
¦
¦ ¦
¦
¦ ¦
80
1
i :
¦ ¦
¦
i :
75% Passing Rate
70
i :
'Acceptance j
Acceptance
60
1 Criteria = ±40%'
i :
Criteria = ± 20%
50
i :
i :
i :
10 jig/L Acceptance
Criteria Boundary
411
i
0 5 10 15 20
Concentration of Sample (|ig/L)
A Data Below 10 ug/L ¦ Data Above 10 ug/L PTRL - - - - PQL
6.2.1.2.3 Conclusions for Toluene
The high laboratory passing rates (above 75 percent) at concentrations below the current PQL of
5.0 |ig/L suggest that the PQL could be lowered. Two new analytical methods have been
approved since 2007. However, only 4 percent of the data provided by the PT providers
represents data from the two new methods EPA 524.3 and EPA 524.4, out of which only two
data points are below the current PQL. Due to lack of sufficient data from the two new methods,
it is unknown whether these methods are expected to improve analytical performance below the
current PQL.
6.2.2 PQL Assessment May Support Reduction of the Current PQL
None of the analytes under consideration fall under this category.
6.2.3 PQL Assessment Does Not Support Reduction of the Current PQL or Data is
Insufficient to Reach a Conclusion
Of the eight analytes mentioned in Section 6.2, six analytes have an existing PQL that is less
than the MCL and their PT data either indicate that the PQL should not be lower or their PE/PT
data are insufficient to reach a conclusion.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-21
December 2016
-------
6.2.3.1 Carbofuran
6.2.3.1.1 Results of the Method Comparison
Exhibit 6.21 summarizes the MDLs for carbofuran as documented in EPA-developed analytical
methods. No updated or new analytical methods have been approved for the analysis of
carbofuran in drinking water samples during the years 2008-2014.
Exhibit 6.21: Analytical Methods for Carbofuran
EPA Methods
Approved for the
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of
Drinking Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
531.1
DAI/ HPLC with Post Column Derivatization
0.52
531.2
DAI/ HPLC with Post Column Derivatization
0.043 - 0.058
Notes:
Regulatory DLs for organic compounds are listed at 40 CFR 141.24(h)(18).
Acceptance Criteria for organic compounds are listed at 40 CFR 141.24(h)(19)(i)(B).
MCL = 40 |jg/L
Current PQL = 7.0 |jg/L
DL = 0.9 |jg/L
Acceptance Criteria = ± 45%
6.2.3.1.2 Results of the PQL Analysis
The current PQL for carbofuran is 7.0 |ig/L while the PTRL is 8.3 |ig/L. The data obtained from
the PT providers is summarized in Exhibit 6.22, along with a regression analysis. The entire data
obtained from the PT providers is based on using EPA Methods listed in Exhibit 6.21. None of
the data is below the current PQL of 7.0 |ig/L or below the PTRL of 8.3 |ig/L. Except for one
point, the passing rate for all the data is at or above 75 percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-22
December 2016
-------
Exhibit 6.22: Evaluation of PT Data - Carbofuran
100
95
90
85
80
75
70
65
60
55
50
75% Passing
PTRL = 8.3 (Jg/L
PQL = 7.0 |Jg/L
Acceptance
Criteria = ±45%
15 30 45 60 75 90 105
Concentration of Sample (rrg/L)
120
135
150
A All Data
PTRL - - - - PQL
6.2.3.1.3 Conclusions for Carbofuran
Given lack of data below the current PQL of 7.0 |ig/L, it may not be appropriate to recommend
lowering of the PQL. No new or revised methods that may be expected to improve analytical
performance below the current PQL (and hence suggest possible reduction of the PQL) have
been approved since 2007.
6.2.3.2 Cyanide
6.2.3.2.1 Results of the Method Comparison
Exhibit 6.23 summarizes the MDLs for cyanide as documented in EPA-developed analytical
methods. The MDLs for some of the methods are not known. Two new analytical methods,
Kelada-01 (USEPA, 2001), QuickChem-10-204-00- 1-X (Lachat) (Lachat Instruments, 2000) and
OIA-1677, DW (USEPA, 2004), were approved for the analysis of cyanide in drinking water
samples during the years 2008-2014. The MDLs for the new methods are considerably lower
than those of the existing EPA Methods.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-23
December 2016
-------
Exhibit 6.23: Analytical Methods for Cyanide
EPA Methods Approved
for the Analysis of
Drinking Water
EPA Methods Approved for the Analysis of
Drinking Water - Technique
EPA Methods
Approved for
the Analysis of
Drinking Water -
MDL (mg/L)
335.4
Semi-Automated Colorimetry
No MDL
SM 4500-CN C 1
Manual Distillation
No MDL
SM 4500-CN E 1
Colorimetry
No MDL
SM4500-CN F
Cyanide-Selective Electrode Method
50
SM4500-CN G 2
Cyanides Amenable to Chlorination after Distillation
20
Kelada-01*
UV, Distillation, Spectrophotometric
0.5
QuickChem-10-204-00-1 -
X (Lachat) *
Micro Distillation, Flow Injection, Spectrophotometric
0.6
OIA-1677, DW* 3
Ligand Exchange and Amperometry
0.5
Notes:
* New EPA approved analytical methods since last Six-Year Review.
1 This method is equivalent to American Society for Testing and Materials (ASTM)
2036-98 A as per 40 CFR 141,23(k)(1).
2 This method is equivalent to ASTM 2036-98 B as per 40 CFR 141.23(k)(1).
3 This method is equivalent to ASTM D6668-04 as per 40 CFR 141.23(k)(1).
Regulatory DLs for inorganic compounds are listed at 40 CFR 141.23(a) 4(i).
Acceptance Criteria for inorganic compounds are listed at 40 CFR 141.23(k)(3)(ii).
MCL = 200 |jg/L
Current PQL = 100 |jg/L
DL = 0.6 - 20 |jg/L
Acceptance Criteria = ± 25%
6.2.3.2.2 Results of the PQL Analysis
The current PQL for cyanide is 100 |ig/L while the PTRL is 75 |ig/L. The data obtained from the
PT providers is summarized in Exhibit 6.24, along with a regression analysis. Approximately 39
percent data is based on using EPA Method 335.4, 51 percent data is based on using Standard
Method 4500 and 10 percent data is based on using the three new methods shown in Exhibit
6.23. None of the data is below the current PQL of 100 |ig/L or below the PTRL of 75 |ig/L.
Except for one point, the passing rate for the entire data set is above 75 percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-24
December 2016
-------
Exhibit 6.24: Evaluation of PT Data - Cyanide
100
95
90
J? 85
'<7i
U)
flj
80
-------
Exhibit 6.25: Analytical Methods for Hexachlorocyclopentadiene
EPA Methods
Approved for the
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of
Drinking Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
505
ME and GC
0.13
508
GC/ECD
No MDL
508.1
LSE and ECGC
0.004
525.2
LSE and CCGC/MS
0.072-0.16
525.3*
SPE and CCGC/MS
0.0055- 0.012
551.1
LLE/GC w/ECD
0.016-0.018
Notes:
* New approved analytical methods since last Six-Year Review.
Regulatory DLs for organic compounds are listed at 40 CFR 141.24(h)(18).
Acceptance Criteria for organic compounds are listed at 40 CFR 141.24(h)(19)(i)(B).
MCL = 50 |jg/L
Current PQL = 1.0 |jg/L
DL = 0.1 |jg/L
Acceptance Criteria = Mean ± 2 Std Dev
6.2.3.3.2 Results of the PQL Analysis
The current PQL for hexachlorocyclopentadiene is 1.0 |ig/L while the PTRL is 0.5 |ig/L. The
data obtained from the PT providers is summarized in Exhibit 6.26, along with a regression
analysis. The entire data obtained from the PT providers is based on using EPA Methods listed in
Exhibit 6.25 and does not include any data by the new EPA Method 525.3. Only two data points
are below the current PQL of 1.0 |ig/L or below the PTRL of 0.5 |ig/L (and do not include the
new Method 525.3). Except for one point, the passing rate for all the data is at or above 75
percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-26
December 2016
-------
Exhibit 6.26: Evaluation of PT Data - Hexachlorocyclopentadiene
100
95
90
85
I/)
re
80
tA
Q)
2 75
re
k.
O
-§ 70
o
S? 65
60
55
50
0 2 4 6 8 10 12 14 16 18 20
Concentration of Sample (jig/L)
i All Data - PTRL PQL
6.2.3.3.3 Conclusions for Hexachlorocyclopentadiene
Given that limited is below the current PQL of 1.0 |ig/L, it may not be appropriate to recommend
lowering of the PQL. One new method has been approved since 2007 but since the data provided
by the PT providers does not include this method, it is unknown whether it is expected to
improve analytical performance below the current PQL (and hence suggest possible reduction of
the PQL).
6.2.3.4 Oxamyl
6.2.3.4.1 Results of the Method Comparison
Exhibit 6.27 summarizes the MDLs for oxamyl as documented in EPA-developed analytical
methods. No updated or new analytical methods have been approved for the analysis of oxamyl
in drinking water samples during the years 2008-2014.
75% Passing
Acceptance Criteria = Mean ±2 Std Dev
Analytical Feasibility Support Document for
the Third Six-Year Review
6-27
December 2016
-------
Exhibit 6.27: Analytical Methods for Oxamyl
EPA Methods
Approved for the
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of
Drinking Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
531.1
Direct Aqueous Injection (DAI)/ HPLC with Post
Column Derivatization
0.86
531.2
DAI/ HPLC with Post Column Derivatization
0.045 - 0.065
Notes:
Regulatory DLs for organic compounds are listed at 40 CFR 141.24(h)(18).
Acceptance Criteria for organic compounds are listed at 40 CFR 141.24(h)(19)(i)(B).
MCL = 200 |jg/L
Current PQL = 20 |jg/L
DL = 2.0 |jg/L
Acceptance Criteria = Mean ± 2 Std Dev
6.2.3.4.2 Results of the PQL Analysis
The current PQL for oxamyl is 20 |ig/L while the PTRL is 11 |ig/L. The data obtained from the
PT providers is summarized in Exhibit 6.28, along with a regression analysis. The entire data set
provided by the PT providers is based on the two EPA Methods listed in Exhibit 6.27. Two data
points are below the current PQL of 20 |ig/L and no points are below the PTRL of 11 |ig/L.
Except for one point, the passing rate for all the data is at or above 75 percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-28
December 2016
-------
Exhibit 6.28: Evaluation of PT Data - Oxamyl
100
95
90
g> 85
'\S>
-------
Exhibit 6.29: Analytical Methods for Selenium
EPA Methods
Approved for
the Analysis of
Drinking Water
EPA Methods Approved for the Analysis of Drinking
Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
EPA 200.5
Axially Viewed ICP-Atomic Emission Spectrometry
1.3
EPA 200.7
ICP - Atomic Emission Spectroscopy
2.0
EPA 200.8
ICP-MS
0.5
EPA 200.9
Stabilized Temperature Graphite Furnace Atomic
Absorption
2.0
SM 3113B1
Electrothermal Atomic Absorption Spectrometry
No MDL
SM 3114B/
Hydride Generation/Atomic Absorption Spectrometry
2.0
SM 3114B-972
SM 3114C
Continuous Hydride Generation/Atomic Absorption
Spectrometry
No MDL
SM 3120A
ICP Emission Spectroscopy
No MDL
SM 3125
ICP/MS
1.0
Notes:
1 This method is equivalent to ASTM 3859-98 03A as per40CFR 141.23(k)(1).
2 This method is equivalent to ASTM 3859-98 03B as per 40 CFR 141.23(k)(1).
Regulatory DLs for inorganic compounds are listed at 40 CFR 141.23(a)(4)(i).
Acceptance Criteria for inorganic compounds are listed at 40 CFR 141.23(k)(3)(ii).
MCL = 50 |jg/L
Current PQL = 10 |jg/
DL = 2.0 |jg/L
Acceptance Criteria = ± 20%
6.2.3.5.2 Results of the PQL Analysis
The current PQL for selenium is 10 |ig/L while the PTRL is 8 |ig/L. The data obtained from the
PT providers is summarized in Exhibit 6.30, along with a regression analysis. Approximately 82
percent data is based on using EPA Methods listed in Exhibit 6.29 while 18 percent data is based
on using the Standard Methods listed in Exhibit 6.29. As shown in Exhibit 6.30, except for one
data point, all the data is above the current PQL of 10 |ig/L and above the PTRL of 8 |ig/L. The
passing rate for the entire data set is above 75 percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-30
December 2016
-------
Exhibit 6.30: Evaluation of PT Data - Selenium
100
95
aA aa
90
85
80
75% Passing Rate
75 ¦
70
Acceptance
Criteria = ±20%
65
60
55
50
0
10
20
30
40
50
60
70
80
90
100
Concentration of Sample (|ig/L)
A All Data PTRL - - - - PQL
6.2.3.5.3 Conclusions for Selenium
Given the variable laboratory passing rates for the data set and the limited data (only one data
point) below the current PQL of 10 |ig/L, it may not be appropriate to recommend lowering of
the PQL. It is noted that in 2007, revisions were made to two methods, i.e. ASTM 3859-98A and
ASTM 3859-98B were modified to ASTM 3859-93 A and ASTM 3859-93B, respectively. These
revisions were minor modifications associated with hazardous materials handling and safer
techniques to conduct hazardous or complicated analytical procedures and are not related to
changes in procedures or instrumentation. No new or revised methods that may be expected to
improve analytical performance below the current PQL (and hence suggest possible reduction of
the PQL) have been approved since 2007.
6.2.3.6 Xylenes
6.2.3.6.1 Results of the Method Comparison
Exhibit 6.31 summarizes the MDLs for xylenes as documented in EPA-developed analytical
methods. Two new analytical methods, EPA Method 524.3 (USEPA, 2009b) and EPA Method
524.4 (USEPA, 2013), were approved for the analysis of xylenes in drinking water samples
during the years 2008-2014. The MDL for the new EPA Method 524.4 is not known. The MDL
for the new EPA Method 524.3 is in the range of the MDL for EPA Method 524.2 and slightly
higher than the MDL for EPA Method 502.2.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-31
December 2016
-------
Exhibit 6.31: Analytical Methods for Xylenes
EPA Methods
Approved for the
Analysis of
Drinking Water
EPA Methods Approved for the Analysis of Drinking
Water - Technique
EPA Methods
Approved for the
Analysis of Drinking
Water - MDL (|jg/L)
EPA 502.2
Purge and Trap CCGC with Photoionization and ECDs
in Series
0.01
EPA 524.2
CCGC/MS
0.03-0.13
EPA 524.3*
CCGC/MS
0.05
EPA 524.4*
GC/MS using Nitrogen Purge Gas
No MDL
Notes:
* New approved analytical methods since the last Six-Year Review.
Regulatory DLs for volatile organic compounds are listed at40CFR 141.24(k)(17)(ii)(C).
Acceptance Criteria for volatile organic compounds are listed at 40 CFR 141.24(f)(17)(i): http://www.nelac-
institute.orq/docs/pt/DW FOPT 2012 01 03.pdf.
MCL = 10,000 |jg/L
Current PQL = 5.0 |jg/L
DL = N/A
Acceptance Criteria = ± 40% at < 10 |jg/L or± 20% > 10 |jg/L
6.2.3.6.2 Results of the PQL Analysis
The current PQL for xylenes is 5.0 |ig/L while the PTRL is 1.2 |ig/L. The data obtained from the
PT providers is summarized in Exhibit 6.32, along with a regression analysis. Approximately 96
percent data is based on using EPA Methods 502.2 and 524.2 as listed in Exhibit 6.31 while 4
percent data is based on using the new EPA Methods 524.3 and 524.4 listed in Exhibit 6.31.
Since the acceptance criteria is ±40 percent at spike concentrations below 10 |ig/L and ±20
percent at or above 10 |ig/L, the data is regressed as two independent populations. As shown in
Exhibit 6.32, none of the data is below the current PQL of 5.0 |ig/L or below the PTRL of 1.2
|ig/L. Except for two points, the passing rates for the rest of the data are at or above 75 percent.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-32
December 2016
-------
Exhibit 6.32: Evaluation of PT Data - Xylenes
1
1 . >
¦¦¦
i :
i :
." . ¦" ¦" ¦ ¦"
¦ ¦ ¦ ¦
¦
¦
¦
¦
i ;
i .
75% Passing Rate
lAcceptance
¦
Acceptance
|Criteri£i = ±40%
1 1
1 1
i :
10 |_ig/LAcceptance
Criteria Boundary
Criteria = ±20%
10 15 20 25 30 35
Concentration of Sample (ug/L)
40
45
50
A Data Below 10 ug/L ¦ Data Above 10 ug/L PTRL - - - - pql
6.2.3.6.3 Conclusions for Xylenes
Given the variable laboratory passing rates for the data set and the lack of data below the current
PQL of 5.0 |ig/L, it may not be appropriate to recommend lowering of the PQL. Two new
methods have been approved since 2007 but since this data does not fall below the current PQL,
it may not be expected to improve analytical performance below the current PQL (and hence
suggest possible reduction of the PQL).
Analytical Feasibility Support Document for
the Third Six-Year Review
6-33
December 2016
-------
6.3 Summary
This document examines analytical method performance over time by determining if the PQLs
may have changed since promulgation. PQL assessments are presented by means of linear
regression of available PE/PT data. A qualitative conclusion is drawn by presenting a
recommendation of whether a PQL might be reduced. In addition, analytical method
performance is also assessed by comparing the MDL of the analytical methods which were
available at the time of promulgation to those of the currently approved methods.
Exhibit 6.33 and Exhibit 6.34 provide summary observations the PE/PT data review of the 16
analytes that were included in the Six-Year Review 3. The summary tables also include a
notation as to whether any recently approved analytical methods or updates (i.e., 2007 to 2014)
are available for these analytes that might indicate improved laboratory performance at low
concentrations. Lastly, a recommendation as to whether a PQL can be reduced is provided (these
analytes are italicized). The recommendations were made based on the availability of PE/PT data
in the vicinity of and/or below the PQL, and outliers. The qualitative conclusions are based
primarily on data that are in the vicinity of and/or below the PQL (for VOCs, this corresponds to
concentrations <10 |ig/L).
The recommendations to not reduce the PQL/MCL could be related to many factors, since the
PE/PT data sets may reflect one or more of the following traits:
No PE/PT data or insufficient data is available at or below the PQL,
Laboratory performance is poor as PE/PT data approaches the PQL, and/or
Laboratory performance is highly variable over the range of concentrations analyzed.
The overall assessment decision presented in the final columns of Exhibit 6.33 consists of the
following possible outcomes:
Regulated contaminants for which the MCL is set at the PQL, and thus, the PQL is
limiting
o PQL assessment supports reduction of the current PQL;
o PQL assessment may support reduction of the current PQL; and
o PQL assessment does not support reduction of the current PQL, or data are
inconclusive or insufficient to reach a conclusion.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-34
December 2016
-------
Exhibit 6.33: Analytical Feasibility Assessment Summary for Analytes with MCL
Equal to the Current PQL
Analyte
Units
Current
MCL
New or
PQL
Qualitative
PQL
Updated
Methods?
Assessment
Results
Recommendation
Chlordane
ijg/i
2
2
Yes - not
known if it
improves
analytical
performance in
vicinity of
current PQL
No data
-------
The overall assessment decision presented in the final columns of Exhibit 6.34 consists of the
following possible outcomes:
Regulated contaminants for which the MCL is greater than the PQL
o PQL assessment supports reduction of the current PQL;
o PQL assessment may support reduction of the current PQL; and
o PQL assessment does not support reduction of the current PQL, or data are
inconclusive or insufficient to reach a conclusion
Analytical Feasibility Support Document for
the Third Six-Year Review
6-36
December 2016
-------
Exhibit 6.34: Analytical Feasibility Assessment Summary for Analytes with MCL
Greater than the Current PQL
Analyte
Units
Current
PQL
MCL
New or Updated
Methods?
PQL
Assessment
Results
Qualitative
Recommendation
Carbofuran
ijg/i
7
40
No
No data
-------
As shown in Exhibit 6.33 and Exhibit 6.34, of the 16 analytes that were analyzed as part of this
report, the qualitative recommendations for PQL assessment are summarized as follows:
For eight analytes, the PQL is equal to the MCL and hence the PQL is limiting. For all
the eight analytes, the PE/PT data does not support reduction of the current PQL. Out of
these eight analytes, new or improved analytical methods are available for three analytes
(chlordane, l,2-dibromo-3-chloropropane and pentachlorophenol). However, it is not
known if the new method(s) are expected to improve analytical performance in the
vicinity of the current PQL. For the remaining five analytes (dioxin, heptachlor,
heptachlor epoxide, thallium and toxaphene), new or improved analytical methods are not
available.
For eight analytes, the PQL is lower than the MCL and hence, the MCL may be reduced.
Of the eight analytes, two analytes have PE/PT data that support further reduction of the
PQL. For these two analytes (cis-l,2-dichloroethylene and toluene), new or improved
analytical methods are available. However, it is not known if these new method(s) are
expected to improve analytical performance in the vicinity of the current PQL. For the
remaining six analytes, PE/PT data does not support the reduction of the current PQL.
Out of these six analytes, new or improved analytical methods are available for three
analytes (cyanide, hexachlorocyclopentadiene and xylenes). However, it is not known if
the new method(s) are expected to improve analytical performance in the vicinity of the
current PQL.
It is noted that for the analytes with improved laboratory methods, the existence of new methods
may not directly translate to improved analytical performance, even with improved detection
limits. It is possible that only a small number of laboratories will use a new method, or it may
take time for the method to be utilized to its full effectiveness.
Analytical Feasibility Support Document for
the Third Six-Year Review
6-38
December 2016
-------
7 References
Lachat Instalments. 2000. Digestion and Distillation of Total Cyanide in Drinking and
Wastewaters Using MICRO DIST and Determination of Cyanide by Flow Injection Analysis,"
Revision 2.1. November 30, 2000.
USEPA. 1985a. National Primary Drinking Water Regulations; Volatile Synthetic Organic
Chemicals; Final Rule and Proposed Rule. 50FR 46880. November 13, 1985.
USEPA. 1985b. National Primary Drinking Water Regulations; Volatile Synthetic Organic
Chemicals; Proposed Rule. 50 FR 46902. November 13, 1985.
USEPA. 1987. National Primary Drinking Water Regulations - Synthetic Organic Chemicals;
Monitoring for Unregulated Contaminants; Final Rule. 52 FR 25690. July 8, 1987.
USEPA. 1989. National Primary and Secondary Drinking Water Regulations; Proposed Rule. 54
FR 22062. May 22, 1989.
USEPA. 2001. Kelada Automated Test Methods for Total Cyanide, Acid Dissociable Cyanide,
And Thiocyanate, Revision 1.2. EPA 821-B-01-009. August 2001.
USEPA. 2004. Available Cyanide by Flow Injection, Ligand Exchange, and Amperometry.
EPA-821-R-04-001. January 2004. Available from ALPKEM, A Division of OI Analytical, P.O.
Box 9010, College Station, TX 77842-9010.
USEPA. 2009a. EPA Protocol for the Second Review of Existing National Primary Drinking
Water Regulations.
USEPA. 2009b. Development of Estimated Quantitation Levels for the Six-Year Review of
National Primary Drinking Water Regulations.
USEPA. 2012. EPA Method 525.3. Determination of Semi-Volatile Organic Chemicals in
Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass
Spectroscopy (GC/MS). EPA 600-R-12-010. February, 2012. Available at
https://cfpub.epa.gov/si/si public record report.cfm?dirEntryId=241188&simpleSearch=l&sear
chAll=525.3.
USEPA. 2013. EPA Method 524.4. Measurement of Purgeable Organic Compounds in Water by
Gas Chromatography/Mass Spectrometry Using Nitrogen Purge Gas. EPA 815-R-13-002. May
2013. http://www.epa.gov/scitech/drinkingwater/labcert/methods_index.cfm
Weisberg, S. 1985. Applied Linear Regression, New York: John Wiley & Sons, Inc.
Analytical Feasibility Support Document for
the Third Six-Year Review
7-1
December 2016
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