STATUS REPORT ON ANALYTICAL METHODS
TO SUPPORT THE DISINFECTANT/DISINFECTION
BY-PRODUCTS REGULATION
August 1992
Background
The United States Environmental Protection Agency (EPA) is
developing national regulations to cc..trol disinfectants and
disinfection by-products (D/DBPs) in public drinking water
supplies. Twelve D/DBPs have been identified for possible
regulation under this rule123, based on available occurrence,
exposure, and health effects data. EPA intends to set maximum
contaminant levels (MCLs) for these D/DBPs, and analytical
methods will be specified for use in demonstrating compliance
with each MCL. This document provides a summary of the
analytical methods that EPA intends to propose as compliance
monitoring methods. A discussion of surrogate measurements that
are being considered for inclusion in the regulation is also
provided.
There are several technical issues that EPA is trying to
resolve before the methods discussed in this document are
proposed/promulgated. The public is encouraged to contact EPA,
if they have information that will help EPA in this process.
Information should be addressed to:
Patricia Snyder Fair, Chair
D/DBP Analytical Methods Task Force
U.S. Environmental Protection Agency
Office of Ground Water & Drinking Water
26 W. Martin Luther King Drive
Cincinnati, OH 45268
Disinfectants:
Chlorine and Chloramines. The measurement of chlorine
residuals will be required as part of the D/DBP Rule in order to
demonstrate compliance with MCLs for chlorine and monochloramine.
The utility will have the option of either measuring free or
total chlorine residuals for the chlorine MCL. Compliance with
the monochloramine MCL will be based on a total chlorine residual
measurement, because monochloramine cannot be practically
measured by itself.
There are many analytical methods available for measuring
chlorine residuals, and each has certain limitations. All
methods are subject to interferences, so the accuracy and
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precision of the analysis will vary with matrix. Low level free
chlorine measurements are subject to interference errors from
chlorammes and other oxidants.
Several methods for measuring chlorine residuals were
promulgated with the Surface Water Treatment Rule (SWTR)4: 1)
amperometric titration; 2) DPD ferrous titrimetric method; 3) DPD
colonmetric method; and 4) the leuco crystal violet (LCV)
method. These were referenced to the 16th Edition of Standard
Methods for the Examination of Water and Wastewater5. EPA used
these methods as the starting point for determining methods that
are applicable to the D/DBP Rule. Methods listed in the 17th
Edition of Standard Methods6 were also considered. Table 1
summarizes the methods most likely to be proposed with the D/DBP
Rule. The methods required to demonstrate compliance with the
SWTR will also be updated to be consistent with the D/DBP Rule.
EPA intends to propose three of the four chlorine residual
methods from the SWTR, when the D/DBP Rule is proposed. The LCV
method will not be proposed. It was not included in the 17th
Edition of Standard Methods, due to its relative difficulty and
lack of comparative advantages. EPA thinks it is unlikely that
this method is being used, so dropping it should have little
effect on the regulated community.
EPA is considering approval of two additional methods for
compliance monitoring: 1) the syringaldazine (FACTS) method for
free chlorine and 2) the iodometric electrode method for total
chlorine. Both methods are included in the 17th Edition of
Standard Methods.
Method 4500-C1 E for measuring low levels of total chlorine
residual is also available in the 17th Edition of Standard
Methods. Although it is not useful for measuring total chlorine
residuals at concentrations near the MCL, it is useful for
determining compliance with the SWTR requirements for a
detectable residual in the distribution system. Therefore, EPA
is considering approval of this method when it updates methods
for the SWTR. Data obtained using this method can also be used
to demonstrate compliance with the total chlorine residual MCL in
the D/DBP Rule.
The 18th Edition of Standard Methods1 will be available for
purchase in August, 1992, so the D/DBP Rule will cite it for
descriptions of the chlorine residuals methods. The method
numbers did not change from the 17th to the 18th edition, so the
numbers given in Table 1 can be used with either edition. Since
EPA is required to review its regulations every 3 years, EPA
anticipates incorporating the latest versions of the methods into
the D/DBP Rule each time it is reviewed.
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Historically, EPA has required all analyses that are done to
demonstrate compliance with an MCL, be performed by a certified
laboratory. Because chlorine residuals are not stable, these
samples must be analyzed immediatelv a^:: cannot be transported to
an off-site laboratory. Utility per-sjnnel have been performing
chlorine residual analyses either in the field or m the
treatment plant. EPA feels these measurements should continue to
be made at the water system by any person acceptable to the
State. It is not EPA's intent to require the certification of
each water system for chlorine residual measurements.
EPA will continue to allow the use of DPD colorimetric test
kits for field measurements of chlorine residuals, if they are
approved by the State.
Chlorine Dioxide. The SWTR promulgated two methods for
measuring chlorine dioxide residuals: 1) amperometric titration
and 2) the DPD method. The 16th Edition of Standard Methods wad
cited as the reference. As discussed above for chlorine residual
measurements, the latest versions of methods for measuring
chlorine dioxide residuals (see Table 1) will be cited in the
D/DBP Rule.
The 17th Edition of Standard Methods proposes a second
amperometric titration method (4500-C102 E) for measuring
chlorine dioxide residuals. EPA is considering adding it as an
acceptable compliance monitoring method.
The methods for chlorine dioxide residuals are indirect
methods, because the concentrations are determined by difference.
Amperometric titration methods are preferred over the DPD method,
if they are used by highly trained personnel.
It is EPA's intent to continue to allow the measurement of
chlorine dioxide residuals at the water system by any person
acceptable to the State.
Due to the limitations of the current methodology, EPA is
seeking information on new methodology that may be applicable for
compliance monitoring. New methods must provide demonstrated
advantages over the current methods and have the potential for
being distributed in a standard format to interested public in
the timeframe of the D/DBP regulation. New methods must be
useable in the field or by utility personnel.
Disinfection Bv-Producta:
Trihalomethanes. There are two methods currently approved
for THM compliance monitoring: EPA Methods 501.1 and 501.2.
These packed column, gas chromatography (GC) methods were
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promulgated with the 1979 THM Rule*. EPA intends to propose two
capillary column GC methods by the end of 1992: EPA Methods
502.2" and 524.2ld. After a 45 day comment period, the methods
will be promulgated, and they can be used for THM compliance
monitoring effective 30 days after promulgation. EPA Methods
502.2 and 524.2 are in general use in many laboratories, because
they are used to measure the concentrations of volatile organic
compounds (VOCs) in drinking water.
EPA Methods 502.1 and 524.l' are not being proposed in 199 2
and they are not being considered for the D/DBP Rule, because
they use packed column chromatography. The GC technology has
progressed to the point that packed columns are becoming
obsolete. EPA is considering eliminating packed column GC
methods (EPA Methods 501.1 and 501.2) from the list of approved
THM compliance monitoring methods when the D/DBP Rule is
proposed. This would not be implemented until the monitoring
requirements of the D/DBP Rule become effective.
EPA Method 551" is the only new method that is likely to be
addeu for THM compliance monitoring when the D/DBP Rule is
promulgated. It involves ad}usting the ionic strength of the
sample, extracting the analytes into methyl-tertiary-butyl ether
(MTBE), and analyzing the extract by capillary column GC with
electron capture detection (ECD). This method can also be used
to measure the concentrations of haloacetonitriles, chloropicrin,
1,1-dichloropropanone, 1,1,1-trichloropropanone, and chloral
hydrate, if the appropriate dechlormating agents are used.
Several laboratories around the country have modified EPA
Method 551 by using pentane, instead of MTBE, as the extraction
solvent. When this is done, chloral hydrate (CH) is not included
in the * --lysis, because CH is too polar to be extracted by
pentane. ?A Method 551 permits the analyst to modify GC
columns, C conditions, detectors, extraction techniques,
concentration techniques, internal standard or surrogate
compounds, as long as the analyst demonstrates the modified
method still meets the performance criteria established in the
nethod. Therefore, if Method 551 is approved for THM compliance
^nitoring, approval to use pentane will not be considered
-°ssary as lona is the method performance criteria are met.
: wih eliminate some of the need for approval of alternative
test procedures (ATPs).
Many commercial sources of MTBE are contaminated with
chloroform, necessitating cleanup prior to use in THM analyses.
MTBE can be purified by distillation using appropriate safety
precautions, but it should not be stored for long periods of
time, in order to prevent the formation of peroxides. At least
some lots of OmniSolv (EMScience) MTBE labeled "Suitable for
Spectrophotometry, Liquid Chromatography, Gas Chromatography,
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Residue Analysis, Assay by GC: 99.9% pure" have not contained
measurable levels of chloroform or chlorinated solvents,
indicating suitable purity MTBE can be produced commercially.
This should encourage laboratories to make the need for high
purity MTBE known to their local solvent suppliers.
Manufacturers may be willing to prepare and market special lots,
when they are aware of a market for their product.
The EPA methods that are likely to be approved for
compliance monitoring of THMs are summarized in Table 2. All of
these methods include the option to use ascorbic acid as a
dechlorinating agent. This practice is under review, because
ascorbic acid may cause the loss of brominated THMs under some
conditions. If laboratories are aware of alternatives to the HC1
and ascorbic acid required by EPA Method 524, they are encouraged
to share that information with EPA. (Sodium thiosulfate and HC1
were originally included in 524, but they cause interference
problems with some of the early eluting analytes included in the
method. Thiosulfate and HCl can still be used, if the sample
does not have to be analyzed for the early eluting compounds.)
Chloral Hydrate. EPA Method 551" will be proposed as the
compliance monitoring method for chloral hydrate (CH), but
additional work must be done before the method is ready for
general use. Chloral hydrate is subject to base-catalyzed
hydrolysis, and the current version of the method does not
provide a mechanism for preventing hydrolysis. This method will
require the addition of a preservative, probably in the form of
acidification. Work is underway to evaluate preservatives for
CH. EPA solicits data demonstrating the stability of CH in
drinking water samples. The data must indicate the
dechlorinating agent used, preservation procedure, sample pH,
storage conditions and holding time.
The regular dechlorinating agent (NH4C1) recommended in
Method 551 cannot be used in some drinking water matrices,
because it interferes with the CH analysis. Either ascorbic acid
or sodium sulfite can be used under those circumstances. Since
ascorbic acid causes problems with THM analyses in some matrices,
EPA prefers the use of sodium sulfite. As part of the effort to
evaluate preservation techniques for CH, EPA will look at how
THMs are affected. It is anticipated that a technique can be
developed in which THMs and CH could be measured in the same
sample using EPA Method 551. If successful, this would reduce
the monitoring costs associated with these analytes.
Some laboratories have expressed concern about the safety of
using MTBE. EPA recommends that ether extracts should be stored
in an explosion-proof refrigerator/freezer.
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The availability of standards for CH has been a problem for
laboratories. However, dilute solutions of CH in acetone are now
available from NSI Environmental Solutions, Inc. (Research
Triangle Park, NC) [Catalogue # 001179-01-01, $32.00) This is an
EPA certified standard. A neat standard is available from
Supelco (Bellefonte, PA) [Catalogue # 4-8048]. Other commercial
sources may become available during the next year.
Very few laboratories are doing CH analyses. EPA is not
aware of any commercial laboratories, but this should change over
the next few years as utilities include it as a by-product of
interest in their bench and pilot scale treatment studies.
Chloral hydrate will be included in the EPA Performance
Evaluation (PE) Studies by the end of 1992. This will provide
laboratories an opportunity to evaluate how well the method is
performing for them. It will also provide EPA with an estimate
of how many laboratories are doing CH analyses and how well they
are doing.
Haloacetic Acids. The EPA method that will be proposed for
haloacetic acid (HAA) compliance monitoring will give the analyst
several options. The initial (standard) version of Method 552"
specified the following steps in the procedure: 1) extraction
with MTBE after sample pH adjustment to >11.5; 2) discard MTBE
fraction and adjust pH of sample to <0.5; 3) extraction with
MTBE; 4) concentration and drying of the extract; 5) conversion
of the HAAs to their methyl esters using diazomethane; and 6)
analysis by capillary column GC/ECD.
A microextraction option was later added to EPA Method
55212. This option eliminated the cleanup extraction, extract
concentration, and extract drying steps. The 18th Edition of
Standard Methods will include a microextraction method for
measuring HAAs. EPA is considering it as a compliance monitoring
method, because it is equivalent to the option described in
Method 552.
EPA is also developing a liquid/solid extraction technique
using ion exchange resins and an acidic methanol derivatization
procedure13. A written procedure should be available for public
distribution by the end of 1992, and it will be designated EPA
Method 552.110.
All of the above procedures will be proposed as compliance
monitoring techniques; all will be covered under EPA Method 552.
Giving the analyst the flexibility to choose extraction technique
and derivatization method should make it easier to begin this
analysis in the laboratory. The acidic methanol derivatization
procedure will also eliminate the concern expressed by some
states and other entities over the use of diazomethane due to
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safety issues.
The quantitation procedures specifed in the current version
of EPA Method 552" must be clarified prior to proposal of the
D/DBP Rule. The initial procedure (described above in the first
paragraph under HAAs) does not require that standards be
extracted, and no correction is made for analytes which are not
fully extracted from the aqueous sample (e.g., dibromoacetic acid
[DBAA]). The microextraction option recommends the preparation
of aqueous standards that are carried through the same procedure
as the samples. Using this option, the analytical results are
automatically corrected for less than 100% extraction
efficiencies. Either calibration method will be acceptable for
compliance monitoring, if EPA only sets MCLs for dichloroacetic
acid (DCAA) and trichloroacetic acid (TCAA), because both acids
are extracted from water at > 90% efficiency. However, EPA is
also considering a total HAA (THAA) MCL. Samples from utilities
with high levels of bromide ion in their source water may contain
high levels of the brominated and mixed bromochloro-acetic acids.
Since these acids are not extracted from water as efficiently as
the chlorinated acids, use of the initial HAA analytical
procedure (described above in the first paragraph under HAAs)
would give a lower THAA result than the microextraction
procedure. For this reason, future versions of Method 552 will
specify that aqueous standards be used for calibration purposes.
Analyses performed to meet compliance monitoring requirements for
a THAA MCL must use aqueous standards for calibration purposes.
Five of the HAAs (monochloroacetic acid [MCAA] , DCAA, TCAA,
monobromoacetic acid [MBAA], and DBAA) have been included in EPA
PE studies, since study WS026 (spring, 1990). A calibration
procedure for the HAAs was not specified with the PE studies, so
laboratories reported data from both procedures. Since the two
procedures are not equivalent for several of the HAAs, EPA will
specify that HAA PE samples be analyzed using aqueous standards
in future PE studies.
EPA Method 552 specifies the HAA standards be prepared in
MTBE, but many laboratories are using methanol instead of MTBE.
Recent work by Yuefeng Xie14 at the University of Massachusetts,
indicates that over time the acids will undergo conversion to
their methyl ester analogs when stored in methanol. The
conversion rate varies with analyte and storage conditions.
Unless the analyst specifically checks for this conversion by
analyzing a non-derivatized standard, it is unlikely the problem
would be detected. The use of ester or mixed free acid and ester
standards will provide inaccurate results, due to differences in
extraction efficiencies between acids and esters. EPA has not
studied this problem, but recommends that if laboratories must
continue to use methanol, they monitor their methanol standards
for this conversion, and prepare fresh standards when esters are
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detected. As an alternative, laboratories should prepare HAA
standards in MTBE.
There are 9 haloacetic acids (HAAs) that could potentially
be included in a THAA MCL. However'-ne EPA Method 552 only
includes 6 of the HAAS (MCAA, DCAA, TCAA, MBAA, DBAA, and
broraochloroacetic acid [BCAA]). Tribromoacetic acid (TBAA) is
not included, because it is not reliably measured using the
current techniques. The remaining 2 HAAs (bromodichloroacetic
acid [BDCAA] and dibromochloroacetic acid (DBCAA]) have not been
tested with Method 552, because standards are not commercially
available. It is unlikely that TBAA, BDCAA, or DBCAA will be
included in Method 552 in the timeframe of this regulation.
EPA is aware of three suppliers that are selling or plan to
sell HAA standards:
1)	Supelco, Inc. (Bellefonte, PA) is distributing a
calibration standard that contains MCAA, DCAA, TCAA, MBAA,
DBAA, and BCAA (catalogue # 4-8047). They will also market
a BCAA standard in solution form as a custom chemical.
2)	Absolute Standards, Inc. (New Haven, CT) is selling a
HAA QC sample, containing MCAA, DCAA, TCAA, MBAA, DBAA, 2,4-
dichlorophenol (24DCPh), and 2,4,6-trichlorophenol
(246TCPh). A standard containing the methyl derivatives of
the same compounds is also available, thus, providing
laboratories a mechanism for checking the derivatization
efficiency of their method. BCAA will soon be added to the
free acid standard mixture, and should be available for
release in August, 1992 (catalogue # 30054).
3)	ULTRA Scientific (North Kingstown, RI) plans to release
a standard containing MCAA, DCAA, TCAA, MBAA, DBAA, BCAA,
24DCPh, and 246TCPh (catalogue # PHM-552A) . The standard is
tentatively scheduled for release in early August, 1992,
assuming successful results from a 60 day time storage
study.
EPA believes there will be adequate laboratory capability
available by the time compliance monitoring for HAAs is required.
Sixteen laboratories participated in the WS029 PE study by
analyzing the HAA sample. This number is expected to increase
significantly over the next few years, as laboratories expand
their analyses to address the new regulations.
Chlorit*, (Chlorate) and Bronat*. An ion chromatography
method will be proposed as the compliance monitoring method for
these anions. EPA does not intend to propose an MCL for the
chlorate ion (C103 ) , but a description of the analytical method
is presented here since it can be determined with the chlorite
ion (C102). The current version of EPA Method 300.0 Part B15 can
be used for measuring C102 and C103" in drinking waters. In some
cases, a weaker carbonate eluent may be required16, because C102"
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elutes in the void volume in high ionic strength samples. A
change in the eluent strength is permitted as part of Method
300.0 Part B, as long as the analyst demonstrates that the
quality control requirements outlined in the method are met (see
Sections 10.1.1 and 11.1 of the method).
Chlorite ion is unstable in many waters'1, so a preservation
technique will be required if the samples cannot be analyzed
within 15 minutes of collection. Recent studies1618 indicate
ethylenediamine (EDA) is a suitable preservative for CIO-,, and it
does not adversely affect analysis of the other anions at the
concentrations typically found in drinking water. Therefore, EPA
is considering requiring the addition of EDA to samples analyzed
for C102 compliance monitoring.
Measurement of ClOj' in samples containing a free chlorine
residual will also require the use of EDA. Free chlorine reacts
with C103' to form CIO, and chloride.
Samples containing a chlorine dioxide residual must be
sparged with an inert gas (e.g., He or Ar) at the time of
collection to eliminate the chlorine dioxide. Otherwise, CIO,
will continue to form C102' and CIO,' in the samples. Prior to
sparging, the samples must be protected from light to prevent
photodecomposition of the chlorine dioxide to form CIO,' and C103"
19
EPA is aware of other techniques (e.g., flow injection
analysis [FIA]) that are being used to measure chlorite and
chlorate. FIA and/or any other applicable procedure will be
considered as a potential compliance monitoring method, if it is
demonstrated to be as accurate and precise as ion chromatography.
The technique would have to be available in a standard format for
public distribution.
Analyses for bromate ion in drinking water samples will
require a modification to the EPA ion chromatography method, due
to the interference from chloride present in these matrices. One
approach is to pretreat the sample with a silver media in order
to remove the chloride20. When this technique is used, traces of
silver are deposited on the IC analytical column, necessitating
the removal of silver before using the column for bromide
analyses. Another alternative is to change the eluent. Recent
studies'614 demonstrate that substituting a borate eluent for the
carbonate eluent specified in the method not only provides the
resolution required to quantitate bromate ion in drinking water,
but also gives a more stable baseline. All the DBP anions can be
measured using the same chromatographic conditions with the
borate eluent. Sections 10.1.1 and 11.1 of EPA Method 300.0 Part
B permit the use of the borate eluent as long as the analyst
demonstrates that the quality control requirements outlined in
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the method are met.
EPA is concerned about the ability to reliably measure
bromate at the levels necessary for.tttis regulation. Studies are
underway in several laboratories, including EPA, to examine ways
to lower the detection limit for this anion. Concentration
techniques are the most promising avenues of research. EPA
requests information on any techniques that are demonstrated to
be effective in drinking water matrices.
Chlorite, chlorate and bromate ions are now included in EPA
PE studies. Thirteen laboratories participated in study WS029.
Surrogate Measurements:
Simulated Distribution System (SDS) Test. EPA may consider
the use of a Simulated Distribution System (SDS) test as a
surrogate measurement of DBP concentrations in the distribution
system. EPA will recommend a modified version of the procedure
described in Method 5710 E in the 17th edition of Standard
Methods (reference will be updated to the 18th edition when
proposed). The method is written for use in determining THM
concentrations, but it can be extended to other DBPs as long as
appropriate dechlormating agents are used after the storage
period. Results of the test are not valid, if there is no
detectable chlorine residual at the end of the storage period.
If the test is used to determine a "worst case" for consumer
exposure, then the sample storage period should be representative
of the maximum distribution system temperature, pH, chlorine
concentration and the longest detention time in the distribution
system. EPA will accept data comparing results from the SDS test
to actual distribution system samples. The data must include a
full description of the SDS test conditions, including
dechlorination procedures and analytical methods used to
quantitate the DBPs. Information concerning the data from
distribution system samples should include temperature, chlorine
residuals, pH, and approximate detention time of the water in the
system.
Total Organic Carbon. There are 3 methods for measuring
organic carbon listed in the 17th Edition (18th Edition) of
Standard Methods, and 2 of them are applicable to requirements of
the D/DBP rule. The persulfate-ultraviolet oxidation method
(53 10 C) and the wet-oxidation method (5310 D) provide the
sensitivity necessary for low level organic carbon measurements,
so they will be recommended if organic carbon is proposed in the
D/DBP rule as a surrogate measurement for DBP precursors.
Depending upon the sample pretreatment, several different organic
carbon fractions are measured by these methods. If the sample is
filtered through a 0.45^m pore size filter before analysis,
Dissolved Organic Carbon (DOC) is measured. Purging the sample
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prior to analysis results in the measurement of Nonpurgeable
Organic Carbon (NPOC). Both of these parameters have been used
as indicators of raw water quality. EPA will accept information
concerning the use of DOC or NPOC as a surrogate for DBP
precursors in source water.
Total Organic Kalide. Method 5320 B in the 17th Edition
(18th Edition) of Standard Methods will be recommended for
determining Total Organic Halide (TOX). The sample must be
dechlorinated and acidified at the time of collection. Sodium
sulfite crystals or a FRESHLY prepared sulfite solution should be
used for dechlorination. Following dechlorination, the sample is
acidified to a pH < 2 using nitric acid in order to preserve the
sample. If the bottles must be shipped to the sampling site with
the reagents already present in the bottles, then sulfuric acid
should be substituted for nitric acid. Department of
Transportation (DOT) regulations must be followed when shipping
bottles containing sulfite and sulfuric acid.
UV Absorbance. There is not a standardized method for this
parameter. The technique originally used to establish a
relationship between raw water UV absorbance and THM formation
involved filtering the sample through a 0.45/xm pore size filter
and then measuring UV absorbance at 254 nm. The filter must be
prewashed to remove water-soluble organics. EPA will accept
information concerning the applicability of alternative
procedures for defining this measurement.
EPA is evaluating its data to determine the relationship
between TOC and UV absorbance. It may be necessary to measure
both parameters in order to better characterize raw water
quality.
EPA will accept data demonstrating interferences to the UV
measurement at 254 nm that would prevent its use in specific raw
waters.
General Comments:
EPA knows the laboratory capacity for doing DBP compliance
monitoring samples is not yet in place. However, EPA believes
the capacity can be developed by the time monitoring requirements
take effect. PE samples will be available for all the DBPs
during 1992, so laboratories can take advantage of those
opportunities to demonstrate competency. Part of the laboratory
certification process will involve successful performance in PE
studies. Laboratories can request PE samples through their State
Certification Officer and participation is free.
EPA does not have interlaboratory method performance data
for the non-THM DBP methods. EPA anticipates that good
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laboratories will be able to achieve quantitative results on
analyses of PE samples that are within at least ± 40 % of the
sample's true value for the non-THM DBPs. However, this has yet
to be demonstrated. Some performance data will be generated
using the results from PE studies. EPA will also examine
alternatives ways to obtain the data, such as round robin studies
among several laboratories currently analyzing drinking water
samples for DBPs.
The most recent PE studies that included the THMs indicated
that the majority of the laboratories participating m the
studies were able to achieve results within + 20 % of the THM
sample's true value. Therefore, EPA will continue to require
that level of performance for certification for THM analyses.
References:
1.	USEPA. Status Report on Development of D/DBP Regulations.
Office of Ground Water and Drinking Water. Washington, D.C.
1991.
2.	USEPA. Occurrence Document in Support of the Development of
the D/DBP Regulations. USEPA Publications. Washington, D.C.
in press. 1992.
3.	USEPA. Status Report on Development of MCLGs for
Disinfectants and Disinfection By-products. Office of
Science and Technology. Washington, D.C., 1992.
4.	USEPA. Drinking Water; National Primary Drinking Water
Regulations; Filtration, Disinfection; Turbidity, Giardia
lamblia, Viruses, Legionella, and Heterotrophic Bacteria;
Final Rule. Fed. Reg., 54:124:27486 (June 29, 1989).
5.	Standard Methods for the Examination of Water and
Wastewater, 16th Edition, American Public Health
Association, American Water Works Association, and Water
Pollution Control Federation, 1985.
6.	Standard Methods for the Examination of Water and
Wastewater, 17th Edition, American Public Health
Association, American Water Works Association, and Water
Pollution Control Federation, 1989.
7 . Standard Methods for the Examination of Water and
Wastewater, 18th Edition, American Public Health
Association, American Water Works Association, and Water
Pollution Control Federation, 1992.
8. 40 CFR 141, Subpart C, Appendix C.
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9.	USEPA. Methods for the Determination of Organic Compounds m
Drinking Water, EPA/600/4-88/039, PB91-231480, National
Technical Information Service (NTIS), December 1988 (revised
July 1991).
10.	USEPA. Methods for the Determination of Organic Compounds in
Drinking Water - Supplement II, Environmental Monitoring
Systems Laboratory, Cincinnati, OH, August 1992.
11.	USEPA. Methods for the Determination of Organic Compounds in
Drinking Water - Supplement I, EPA/600/4-90-020, PB91-
146027, NTIS, July 1990.
12.	Barth, R.C. & Fair, P.S. "Disinfection By-Prodcuts:
Analysis of Haloacetic Acids and Chlorophenols;
Microextraction Procedure vs. USEPA Method 552." AWWA Water
Quality Technology Conference (WQTC) Proceedings, November
1990.
13.	Hodgeson, J.W., Collins, J., & Becker, D. "Advanced
Techniques for the Measurement of Acidic Herbicides and
Disinfection Byproducts in Aqueous Samples." Proceedings of
the 14th Annual EPA Conference on Analysis of Pollutants in
the Environment. May 1991.
14.	Xie, Yuefeng, University of Massachusetts, Amherst, MA,
personal communication, May, 1992.
15.	USEPA. The Determination of Inorganic Anions in Water by Ion
Chromatography Method 300.0. Environmental Monitoring
Systems Laboratory, Cincinnati, OH, August 1991.
16.	Hautman, D.P. & Bolyard, M. "Analysis of Oxyhalide
Disinfection By-Products and Other Anions of Interest in
Drinking Water by Ion Chromatography," International Ion
Chromatography Symposium Proceedings. October 1991.
17.	Pfaff, J.D. & Brockhoff, C.A. "Determination of Inorganic
Disinfection By-Products by Ion Chromatography," Jour. AWWA,
82:4:195 (April 1990).
18.	Hautman, D.P. & Bolyard, M. "Analysis of Inorganic
Disinfection By-Products Using Ion Chromatography," AWWA
WQTC Proceedings. November 1991.
19.	Zika, R.G. ET AL. "Sunlight-Induced Photodecomposition of
Chlorine Dioxide," Water Chlorination Chemistry:
Environmental Impact and Health .Effects. Vol. 5, Lewis
Publ., Inc., Chelsea, Mich. (1985).
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20. Kuo, C. and Weinberg, H.S. "Analysis of Inorganic
Disinfection By-Products Using Ion Chromatography," AWWA
WQTC Proceedings. November 1990.
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Table 1. Methods Being Considered for Use in Compliance Monitoring of
Disinfectant Residuals Under the D/DBP Rule
Working
Residual	Methodology	Std Meth*	Range (mg/L)
Free Chlorine
Amperometric Titration
4500-C1 D
>
0. 1

DPD Ferrous Titrimetric
4500-C1 F
>
0. 1

DPD Colorimetric
4500-C1 G
>
0. 1

Syringaldazine (FACTS)
4500-C1 H
>
0. 1
Total Chlorine
Amperometric Titration
4500-C1 D
>
0.1

Amperometric Titration
4500-C1 E
<
0.2

DPD Ferrous Titrimetric
4500-C1 F
>
0. 1

DPD Colorimetric
4500-C1 G
>
0. 1

Iodometric Electrode
4500-C1 I
>
0. 1
Chlorine Dioxide
Amperometric Titration
4500-C102 C
>
0. 1

DPD Method
4500-C102 D
>
0. 1

Amperometric Titration
4500-C102 E
>
0. 1
(proposed)
Method Number Used in the 17th and 18th Editions of Standard Methods.
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Table 2. Methods Being Considered for Use in Compliance Monitoring of Disinfection
By-Products Under the DBP Rule
Working
Residual	Methodology'	EPA Method (Ref)" Rangef (^g/L)
Trihalomethanes
P&T/GC/ElCD & PID
P&T/GC/MS
LLE/GC/ECD
502.2 (9)
524.2 (10)
551 (11)
>	2.0
>0.5
>	0.5
Chloral Hydrate	LLE/GC/ECD
Haloacetic Acids LLE or SPE /GC/ECD
Chlorite & Chlorate IC
Bromate	IC
551	(11)	> 0.5
552	(10&11)	> 5.0
300.0 Part B	(15) >10''
300.0 Part B	(15) >10"
p&T = purge and trap; GC = gas chromatography; E1CD = electrolytic conductivity
detector; PID = photoionization detector; MS = mass spectrometer; LLE = liguid/liguid
extraction; ECD = electron capture detector; SPE = solid phase extraction; IC = ion
chromatography
" Reference for method is given in ().
+ The concentrations listed in this table are estimates of the lowest levels
laboratories can routinely measure with confidence. For methods involving
multianalytes (e.g., THM methods), the range is given for the analyte with the
highest detection/quantitation level.
f+ Based on experience in EPA's laboratory using a borate eluent. These levels may
be optimistic for many drinking water laboratories.
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