Page 1 

## EPA METHOD 557

DETERMINATION OF HALO AC ETIC ACIDS, BROMATE, AND DALAPON IN
DRINKING WATER BY ION CHROMATOGRAPHY / ELECTROSPRAY IONIZATION TANDEM MASS SPECTROMETRY (IC/ESI

- MS/MS)



## RESEARCH SUMMARY

March 2009

by

A. D. Z affiro and M. Z immerman
S haw E nvironmental , I nc

.

P repared for

D . J. M unch

T echnical S upport C enter
O ffice of G round W ater and D rinking W ater
U. S. E nvironmental P rotection A gency C incinnati , O hio 45268Page 2 

## T

**able of**  **C ontents** 

**________________________________ _____** 

**Page**

List of Tables

................................ ................................ ................................ ................................ ... 3

List of F igures

................................ ................................ ................................ ................................ .. 3 List of Acronyms

................................ ................................ ................................ ............................. 4

1.0 Introduction and Background

................................ ................................ .............................. 5

2.0 Chronology of the Method 557 Development Ef fort at EPA

................................ .............. 7

3.0 Preservation

................................ ................................ ................................ .......................... 9

4.0 Standard Preparation Considerations and Storage Stability of Aqueous Standard

Solutions

................................ ................................ ................................ ............................ 1 0

4.1 Standa rd Preparation Considerations

................................ ................................ ..... 1 0

4.2 S tability of Aqueous Standards

................................ ................................ .............. 1 1

5.0 Second Source Verification

................................ ................................ ............................... 1 3

6.0 Accelera ted Storage Stability Studies

................................ ................................ ................ 1 3

7.0 Ch lorite and Chlorate P&A Study

................................ ................................ ..................... 1 5

8.0 EPA Method Performance Data

................................ ................................ ......................... 19

9.0 Second Laboratory Result s

................................ ................................ ................................ 20

10.0 References

................................ ................................ ................................ .......................... 24Page 3 

## List of Tables

**________________________________ _________** 

**Table Title**  **P age** 

1 Presentations and Manuscripts Associated with the Method 557 Development Project

..... 9

2 PDS Storage Stability Results

................................ ................................ ............................ 1 2

3 Calibration Standard Storage Stability Results

................................ ................................ .. 1 2

4 Method Performanc e Quality Control Sample Results, 5

- μg/L Standard

......................... 1 3

5 Accelerated Storage Stability Study in Reagent Water

................................ ..................... 1 4

6 Accelerated Storage Stability Study in Cincinnati Tap Water

................................ ........... 1 5

7 P&A Results at 5 μg/L in the Presence of 1 mg/L Chlorite, and 0.5 mg/L Chlo rate

........ 1 5

8 Southern Nevada Water Authority IC/ESI

- MS/MS Lowest Concentration MRLs

........... 2 1

9 Southern Nevada Water Authority Precision and Accuracy Results for Tap Water

Fortified at 10 μg/L ( n = 9)

................................ ................................ ................................ 2 2

10 Southern Nevada Water Authority Precision and Accura cy Results for Reagent Water

Fortified at 10 μg/L ( n = 9)

................................ ................................ ................................ 2 2

1 1 Southern Nevada Water Authority Precision and Accuracy Results for Synthetic

Matrix Fortified at 10 μg/L ( n = 9)

................................ ................................ .................... 2 2



## List of Figures

**________________________________ ________** 

**Figure Title**  **Page**

1 D ionex AS 24 c olumn: s ynthet ic s ample m atrix f ortified at 5 **μ** g/ L p lus c hlorite (1 mg/ L ) and c hlorate (0.5 mg/ L )

................................ ................................ ...................... 17

2 D ionex AS 24 c olumn: c onductivity t race, s ynthetic s ample m atrix p lus c hlorite

(1 mg/ L ) and c hlorate (0.5 mg/ L )

................................ ................................ ...................... 18

3 Las Vegas t ap w ater f ortified at 10 μg/L a nd a nalyzed on the AS 24

c olumn at the SNWA l aboratory

................................ ................................ ........................ 2 3Page 4 

## List of **A cronyms** 

ACS American Chemical Society

AS24 Analytical Separator 24

BCAA bromochloroacetic acid

BDCAA bromodichloroacetic acid

CDBAA chlorodibromoacetic acid

ClO 2 chlorine dioxide

DBA A dibromoacetic acid

DCAA dichloroacetic acid

DL detection limit

EDA ethylenediamine

EPA U.S. Environmental Protection Agency

ESI electrospray ionization

GC gas chromatography

HAA haloacetic acid

HAA5 five regulated h aloacetic

acids

HAA9 nine haloacetic a cids

IC ion chromatography

IDC Initial Demonstration of Capability

L liter

LCMRL lowest

- concentration, minimum reporting level

MBAA monobromoacetic acid

MCAA monochloroacetic acid

MCL maximum contaminant level μ g microgram

mg milligram

mL milliliter

MRL mi nimum reporting level

MRM multiple reaction monitoring

MS mass spectrometry
MS/MS tandem mass spectrometer

MtBE methyl

- t

- butyl ether

NERL National Exposure Research Laboratory

n number of observations

NH 4 Cl ammonium chloride

P&A precision and accuracy

PDS primary dilution standard

PI principal investigator QC quality control QCS quality control sample

RA A running annual average

RPD relative percent difference

RSD relative standard deviation

SNWA Southern Nevada Water Authority

SOP standard operating procedu re TBAA tribromoacetic acid

TCAA trichloroacetic acid

TSC Technical Support CenterPage 5 

## 1. **0 Introduction and**  **Background**

EPA developed Method 557 as an alternate test procedur e for compliance monitoring of haloacetic acids (HAAs), dalapon, and bromate in drin king water. This introduction provides a brief background o n the regulation of HAAs, a review of existing methods for their detec tion in drinking water, and discusses the developments that led EPA to propose this new approach. This section also explains t he reason EPA included dalapon and bromate in the analyte list.

HAAs are formed during the disinfection of drinking water through a reaction of hypochlorous acid (or hypochlorite) with natural organic matter. Five haloacetic acids (HAA5) are currently

re gulated in drinking water by the U.S. Environmental Protection Agency (EPA) under the Stage

II Disinfection Byproducts (DBP) Rule 1 at a total maximum contaminant level (MCL) of

60 micrograms per liter ( μ g/L). Included in this group are monochloroacetic ac id (MCAA), monobromoacetic acid (MBAA), dichloroacetic acid (DCAA), dibromoacetic acid (DBAA), and trichloroacetic acid (TCAA). Unlike other regulations, the DBP rule sets a minimum reporting limit (MRL) for each of the HAA5 species.

Three EPA methods 2 a nd two Standard Methods 3 are currently approved under the Stage II DBP Rule for compliance monitoring of HAAs. Each method requires extraction of the HAAs into an organic solvent, and then methylation of the analytes using either diazomethane or acidic

me thanol. Extracts are analyzed by gas chromatography (GC) with electron capture detection. Because the methylation efficiencies are not complete for all analytes, each of the approved methods requires the processing of at least five calibration standards to prepare an internal

standard

- based, procedural calibration curve. Quality control (QC) samples also require processing through the entire method.

While th es e GC methods meet EPA’s regulatory need under the Stage II DBP Rule, advances in ion chromatogr aphy/mass spectrometry (IC/MS) created the potential for a direct

- inject approach. A direct

- inject method simplifies the analysis of HAAs by eliminating the extraction and derivatization steps and the associated procedural calibration. Several m ethods fo r HAA analysis based on the use of IC coupled with single

- stage MS were reported in the literature; however, these methods did not demonstrate adequate sensitivity 4 and lacked suitable selectivity

to resolve matrix interferences. 5 In addition, these early attempts w ere subject to interference

, because the ion

- exchange columns available at that time could not separat e common anions (chloride, carbonate, sulfate, and nitrate)

, present in all drinking water sources

, from HAAs.

In 2005, Dionex (Sunnyvale, Ca lifornia) collaborated with MDS/Sciex (Toronto, Canada) to

eva luate the application of IC coupled with electrospray ionization (ESI) /tandem mass spectrometry ( MS/MS ) to HAA analysis. M ethod development projects conducted at the EPA

Technical Support Cente r (TSC) laboratory in Cincinnati had already demonstrate d the potential gains in selectivity and sensitivity via use of MS/ MS as the detection technique for direct

- inject

, drinking water methods

. To eliminate the problem caused by the matrix, Dionex d evel oped an ion

- exchange column with optimized selectivity to separate the common anions in drinking water from the HAA analytes. [Dionex Analytical Separator 24 (AS24), 150 mm x 2 mm i.d.].

The use of this column eliminated the key limitation s inherent in p revious attempts to analyze for HAAs in drinking water u sing a direct

- inject approach: 1) suppression in the ESI interface resulting from the coelution of matrix components , and 2) fouling of the ESI source by thesePage 6 matrix components

. MS/MS provided the s ensitivity required to achieve the promulgate d MRLs

for HAAs

.

In addition to HAA5, the AS24 column separates dalapon ( 2,2

- dichloroprop ionic acid )

, bromochloroacetic acid (BCAA), bromodichloroacetic acid (BDCAA), chlorodibromoacetic acid (CDBAA), and tribr omoacetic acid (TBAA) from common anions; therefore, these compounds were evaluated for inclusion in the proposed IC/ ESI

- MS/MS method . (Note: the group of nine

chlorine

- and bromine

- containing HAA s that include s HAA5, BCAA, BDCAA, CDBAA, and

TBAA are comm only referred to as “HAA9” within the environmental community.) D alapon is regulated in drinking water 6 and it is an analyte in the all of the current GC methods. Dalapon is amenable to analysis using IC

, presumably, for the same reason it amenable to th e GC technique:

i t is a small carboxylic acid with a similar structure and acidity ( pKa ) to HAAs

.

Bromate is regulated under the Stage II DBP Rule

, and EPA has published a number of direct

inject IC methods for this compound ; however, none of these meth ods utilizes MS or MS/MS

detection

. Dionex and MDS/Sciex rec ognized the potential to simultaneously analyze for HAAs and bromate by IC

, and to take advantage of the selectivity offered by MS/MS. For these reasons, bromate was included in the initial eval uations along with HAA9 and dalapon.

Dionex contacted EPA in late 2005 and proposed a collaborative effort to develop a n EPA method for the analysis of HAAs, dalapon, and bromate using the IC/ESI

- MS/MS technique.

EPA agreed and initiated in

- house studie s in early 2006. This document presents a history of the method development effort over the last three years , documents important “lessons learned” and the results of associated studies, which are not included in the published method . Specific

research objectives to validate the IC/ESI

- MS/MS method are listed in the following bullets:

1. T o establish single

- laboratory

, lowest

- concentration

, minimum reporting levels 7
(LCMRLs) in reagent water

2. T o determine single

- laboratory detection limits 8 (DLs) in reagen t water
3. T o verify acceptable precision and accuracy (P&A) in reagent water, synthetic sample matrix (solution of common anions in reagent water), tap water from a ground water source, and tap water from a surface water source

4. T o determine stability of aque ous standards (unlike the GC method, aqueous standards are necessary to efficiently perform the method, and their stability had not been previously documented for these analytes

— with the exception of bromate)

5. T o investigate potential interferences and limi tations of the IC method, including an evaluation of the effect of the presence of chlorite and chlorate anions in drinking waters

treated with chlorine dioxide (ClO 2 )

EPA decided not to investigate preservation techniques because preservation for HAA9 and dalapon were validated during development of the GC methods. EPA decided , based on theoretical grounds, that the preservation agent prescribed in the GC methods is applicable to bromate. This argu ment is presented in Section 3 of this research summar y.

The following graphic summarizes the target compounds evaluated during th e method development effort, their regulatory limits

, existing methods, and the preservation scheme specified in those methods :Page 7 HAAs Other Analytes (Regulatory Limi t)

HAA5 (MRL) MCAA (2 μ g/L) Bromate ( MCL 10 μg/L, MRL 5 μ g/L ) a Dalapon (2,2

- dichloroprop ionic acid) ( MCL b 20 μ g/L )

MBAA (1 μg/L) DCAA (1 μg/L) TCAA (1 μg/L) DBAA (1 μ g/L) HAA9/dalapon/bromate: 100 mg/L NH 4 Cl c Method 557 Preservation

HAA5 (MCL 60 μ g/L RAA d ) HAA9 ( Regulatory Limit )

Preservation

, Existing Methods BCAA (not regulated) 300.1 Bromate: EDA f 50 mg/L e

BDCAA (not regulated) 552.1, 552.2, 552.3 HAA9 /D alapon: 100 mg/L NH 4 Cl CDBAA (not regulated) TBAA (not regulated)

a MRL = minim um reporting level; National Pri mary Drinking Water Regulations: Stage II DBP Rule

. b MCL = maximum contaminant level; National Pri mary Drinking Water Regulations: EPA 816

- F

- 02

- 013, July 2002

c NH 4 Cl = ammonium chloride.

d RAA = running annual average

.

e U

. S

. EPA Office of Ground Water and Drinking Water (other approved bromate methods not listed)

. f EDA = ethylenediamine

.



## 2.0 **Chronology of the Method 557 Development Effort at**

**EPA**

This section is a basic narrative describing the activities and major milestones duri ng this

three

- year effort and provides a record of publications related to Method 5 57. Mr. Alan Zaffiro served as principal investigator (PI) for Shaw Environmenta l, Inc. Messrs. Barry Pepich and Mike Zimmerman were the Shaw program managers, and Mr. Dav e Munch was the EPA project officer. Throughout the project, Shaw collaborated with Dionex. Doug Later, Dr. Richard Jack,

Rida Al

- Horr, and Rosanne Slingsby were the primary points of contact on the Dionex team. Dr.

H oussain El Ari bi was the technical l ead at MDS/Sciex. Dr. Aribi was the first to demonstrate the technique in the MDS/Sciex application laboratory (Concord, Ontario, Canada). Throughout the project, Dionex provided Shaw with prototype versions of the AS24 column. Shaw

evaluate d an “ alpha ” and a “ beta ” version of this column before collecting the final method performance data using a production version of the AS24 column.

EPA performed much of the initial project activity using a Dionex ICS 3000 ion chroma tograph

interfaced to an MDS/ Sciex API 3200 ESI

- MS/MS located in the National Exposure Research Laboratory (NERL) in Cincinnati . (Note that Dr. Aribi performed the original work using an API 4000 MS/MS.) Eventually, problems with response drift using the MDS/Sciex MS/MS platform

forced EP A to seek an alternate MS/MS system. Although the problems with response drift using the MDS/Sciex MS/MS platform could not be resolved, the method was demonstrated in a second laboratory using an MDS/Sciex system. Shaw believes the drift problems experi enced at EPA were caused by the zero

- air generator.Page 8 Dionex provided an alpha version of the AS24 column in May 2006. However, after testing the alpha column at the Dionex applications laboratory, Dr. Al

- Horr concluded that the resin did not

possess eno ugh capacity to accommodate high ionic strength matrices. Dionex optimized the ion exchange resin, adding additi onal capacity, and delivered a beta version of the AS24 column to

EPA in Fe bruary 2007. EPA utilized the beta column to optimize method parame ters, design a suitable aqueous standard preparation technique, and to evaluate the storage stability of the method analytes in aqueous standards and tap water samples.

Because of the problems with response drift related to use of + the MDS/Sciex MS/M S , EP A

moved the Dionex ICS

- 3000 ion chromatograph from the NERL to the TSC laboratory in September 2007 . The ion chromatograph was interfaced to the Waters Quattro Premier XE MS/MS system, which was already resident in the TSC laboratory.

On February 11, 200 8, the AS24 production column was installed, and Shaw began the process of collecting the method performance data that appears in the published method. As observe d when using the API 3200 MS/MS system

, MCAA response was low relative to the other analytes. To ensure that the Waters system was not compromised in any way, annual service was performed

, in cluding cleaning the source, cleaning the T

- wave assembly, a nd servicing the scroll pump

. A Waters service engineer performed the cleaning procedure. MCAA re sponse improved marginally, and

— as with the API 3200

— the low response for MCAA was addressed by use of longer relative dwell times and by optimizing the resolution. Accurate mass

calibration

, as discussed in Section 10.2 of the method

, is nece ssary to e nsure adequate signal

- to

noise response for this analyte.

Collection of the method performance data was completed on May 17, 2008. During these experiments

, two problems of note occurred. On April 24, 2008, after an extended lapse in project activity, peak tailing appeared in the ion chromatograms. Replacing the precolumn immediately restored column performance; that is, peak profiles were again symmetrical. Because tailing peaks limit the analyst’s ability to set divert windows for matrix eliminatio n, this

corrective action measure is included in Section 4 of the meth od. Later, a loss of signal (~ 50 percent area response) in the third Multiple Reaction Monitoring (MRM) function of the

chromato gram (the retention time window in which the trihaloaceti c acids elute) occurred during the first few runs of an analytical sequence. The signal loss coincided with high background conductivity during the third MRM function as measured by the conductivity detector. In this region of the chromatogram, the hydro xide concentration in the gradient is 60 millimolar (mM). The problem was resolved by flushing the column with 60 mM hydroxide prior to beginning a sequence. Apparently, ions collect on the column while the system is idle and the hydroxide

concentration in the gradient is held at the standby level of 7 mM. Users are cautioned about this potential problem in Section 4 and in the procedure section (Sect. 11) of the method.

An additional experiment to evaluate the affect of the presence of chlorite and chl orate in drinking water on precision, accuracy, and band broadening was conducted on May 23, 2008. The findings are discussed in Section 4 of the method; however, the method does not include the supporting data. Thes e are presented in this documen t ( Sect

. 6 ).Page 9 Shaw made oral presentations on the method development effort at the American Chemical Society (ACS) National meeting in 2007 and the National Environmental Monitoring Conference in August 2007 , and presented a poster at the Water Quality Technical Conference (W Q TC, American Wat er Works Association ) in November 2008. Shaw submitted manuscript s, which EPA management approved, for the ACS and WQTC proceedings

. Table 1 lists these

documents and their d ocument numbers

.

On August 15, 2008, Dave Munch s e nt a formal letter to Southern Nevada Water Authority (SNWA) inviting them to participate in the method development project by conducting a second laboratory validation. Alan Zaffiro sent a draft copy of the method (TSC

- 3

- 0371) to SNWA on August 8, 2008

, and followed with LCMRL guidance on September 4, 2008. SNWA completed

the second laboratory validation in early November 2008

. Mr. Zaffiro compiled the results

, which are presented in Section 9 of this report.

TABLE 1. PRESENTATIONS AND MANUSCRIPTS ASS OCIATED WITH THE

METHOD 557 DEVELOPMENT PROJECT

Location Document No. a Document Description

ACS b National meeting, March 2007 TSC

- 3

- 0111 PowerPoint presentation

ACS National meeting, March 2007 TSC

- 3

- 0042 Manuscript for p roceedings

NEMC c 2007, Cambridge , MA TSC

- 3

- 0220 PowerPoint p resentation WQTC, d November 2008 TSC

- 3

- 0374 Manuscript for p roceedings WQTC, November 2008 TSC

- 3

- 0390 Poster

a TSC = Technical Support C enter

. b ACS = American Chemical Society.

c NEMC = National Environmental Monitoring Conf erence. d WQTC = Water Quality Technical Conference (Ame rican Water Works Association, Denver, CO)

.



## 3. **0 Preservation** 

At the direction of the EPA project officer

, Dave Munch, Shaw excerpted the preservation requirements from t he GC method (EPA method 552 .3) . However, b romate is not an analyte in

the GC method

, and because storage stability was not revisited during development of

Method 557, preservation of this anion with NH 4 Cl is untested. To investigate the efficacy of

NH 4 Cl to preserve bromate, Dave Munch, Barry Pepich, and Alan Zaffiro met with Mr. Dan Hautman, EPA TSC, who is an IC expert. Mr. Hautman provided the following explanation,

which enabled EPA to predict

, on theoretical grounds

, that NH 4 Cl would effectively preserve

bromate:

Using the M ethod 552.3 approach, chloramines are formed by the reaction of hypo chlo

rite with the ammonium ion, effectively arresting the chlorine

- mediated formation of HAAs and dalapon. The combined chlorine residual prevents microbiological degradation during sto rage. 9 The question is whether NH 4 Cl would also effectively preserve bromate. Guidance for the preservation of bromate is found in EPA

M ethod 300.1. Method 300.1 specifies EDA as the preservative for this anion . The

mechanism is analo gous to HAA prese rvation using NH 4 Cl

— the formation of bromamines to prevent formation of bromate from bromite during storage. EDA also complexes iron, a function important for the preservation of chlorite in Method 300.1. Because chlorite is not an analyte in the IC meth od and, like EDA, NH 4 Cl will formPage 10 bromamines, NH 4 Cl would be an acceptable preservation agent for bromate when bromate is analyzed by use of the IC method.

At the request of Dave Munch, this explanation does not appear in M ethod 557. However, a note

stat ing that the preservation scheme is identical to the GC method is included in Section 8 of the

method.



## 4. **0 Standard Preparation Considerations and Storage**  **Stability of Aqueous Standard Solutions**

This section discusses the parameters that led to the guid ance f or standard preparation in M ethod

557

, and presents results that support the recommendations for the safe storage time of stan dard

solutions. Shaw and Dionex realized that the availability of stable aqueous standards would be necessary for the effic ient conduct of a direct

- inject approach for the analysis of the method analytes. Dionex and Shaw proposed the preparation of an analyte PDS at a concentration of 1.0 μg/mL in r eagent w ater, and the preparation of aqueous calibration solutions from this P DS by

dilution with r eagent w ater containing 100 mg/L NH 4 Cl

. T he i nternal s tandard PDS was prepared at the same concentration as the a nalyt e PDS (i.e., 1.0 μg/mL ) , so that its st ability could

be inferred from the evaluations of the a nalyte PDS. Standard solutions were stored at 4 ° C in glass vials with polytetrafluoroethylene

- lined silicone septa. Tables in Section 7 of the method present example recipes for the preparation of PDS and calibration solutions.

**4.1**

The HA A method analytes are available as solutions in MtBE. For M ethod 552, some vendors offer dalapon combined with the HAAs in the MtBE solution. Dalapon is also available as a single

- analyte solution in methanol. Bromate is available as certified aqueous s olutions (generally at 1000 μg/mL). Supelco offers three of the i nternal s tandards: MCAA[2

- 13 C], MBAA[1

- 13 C], and DCAA[2

- 13 C] as single

- analyte solutions in MtBE at a concentration of

1000 μg/mL. Dionex now offers all four i nternal s tandards as single

- a nalyte solutions in MtBE

at a concentration of 1000 μg/mL. T he Dionex standards were not available until after Shaw completed the laboratory phase of the project. However , SNWA used them during the second laboratory validation studies. Shaw used the thr ee Supelco i nternal s tandards, and prepared TCAA[2

- 13 C] from custom

- synthesized neat material (Isotec, a member of the Sigma

- Aldrich Group ( **Standard Preparation Considerations**

www.sigma

- aldrich.com/isotec )

. Section 7 of the method l ists c urrent sources for the analytes and i nternal s tandards , and t he guidance for standard preparation in that section is based on these currently available sources.

Because MtBE has limited water solubility (~5 percent ), the method cautions users not to add

more than 0.5 percent by volume when fortifying an aqueous matrix. Shaw and Dionex chose this limit somewhat arbitrarily to build in a wide safety margin. The research team did not formally study the application of larger volumes; however, observations of the dispersion of MtBE in water when added via syringe injection suggest that such precaution is advised. Large

volumes of MtBE tend to bubble quickly toward the surface rather than immediately mix with water. MtBE disperses into small bubbles that qu ickly dissolve when smaller volumes are injected by syringe well under the surface.Page 11 **4.2 Stability of Aqueous Standards**  To evaluate the stability of the aqueous PDS, stored PDS solutions were analyzed periodically against PDS solutions freshly prepared from t he solvent

- based stock standards. To evaluate the stability of the c alibration s tandards, stored c alibration s tandard solutions were analyzed periodically against freshly prepared c alibration s tandards. Both the stored and the fresh

c alibration s tandards were prepared using a common PDS solution. In order to make a defensible assessment of storage stability, stored solutions were subjected to normal use. That is, PDS solutions were often removed from the refrigerator and brought to room temperature for the purpose of preparing dilutions or fortifying samples, and c alibration s tandards were often removed from storage to fill autosampler vials for analytical sequences.

Aqueous PDS solutions of the method analytes at 1.0 μg/mL (1000 μg/L) were evaluated af ter
35 and 77 days o f storage prior to collecting the method performance data . This work was conducted in the NERL laboratory using the API 3200 MS/MS system. These initial evaluations of PDS storage stability are presented in Table 2 . Based on these re sults, Shaw and Dionex concluded that aqueous standards are stable for extended periods, and that it was safe to adopt the proposed aqueous standard preparation approach. During the collection of the method performance data , an aqueous PDS was evaluated f or stability after 82 days of storage to confirm the earlier findings. These later results are also presented in Table 2

.

The stability of aqueous c alibration s tandards was evaluated at concentrations of 2.0 and

5.0 μg/L

. These results are presented in Table 3

.

Based on the results of these studies and discussion with the EPA project officer, Dave Munch, the estimated safe storage time included in Section 7 of Method 557 for PDS solutions ( i nternal

s tandard PDS and a nalyte PDS) is 60 days, and 14 days f or c alibration s tandards. However, the

method recommends that u sers determine safe storage times independently in their own

laboratories.Page 12 TABLE 2

. PDS STORAGE STABILITY RESULTS a Storage Time: 35 Days 77 Days 82 Days Analysis Date: 7/03/2007 5/25/2007 5/ 14/2008

%R b %RSD c

n=3 %R RPD d % R %RSD
n=3 MCAA 98.5 4.0 100 3.0 109 2.5

MBAA 98.5 1.2 96.5 2.3 100 1.0
Bromate 99.8 3.8 90.8 1.8 113 9.9 Dalapon 102 2.7 89.9 3.3 75.1 10
DCAA 100 0.61 96.4 1.2 100 5.2
BCAA 98.9 0.48 101 3.6 105 10

DBAA 100 1.2 10 6 2.8 102 14
TCAA 99.7 0.46 97.4 0.82 100 2.4
BDCAA 96.7 1.8 100 0.60 105 5.5
CDBAA 98.0 14 97.2 7.4 99.2 0.81

TBAA 96.7 1.1 83.8 6.2 91.4 3.4

a MCAA = m onochloroacetic acid; MBAA = monobromoacetic acid; DCAA = dichloroacetic acid; BCAA =

bromochloroa cetic acid; DBAA = dibromoacetic acid; TCAA = trichloroacetic acid; BDCAA = bromodichloroacetic acid; CDBAA = chlorodibromoacetic acid; TBAA = tribromoacetic acid.
b %R = p ercent recovery.

c %RSD = p ercent relative standard deviation. d RP D = relative perc ent deviation.

TABLE 3

. CALIBRATION STANDARD STORAGE STABILITY RESULTS a

Storage Time: 10 Days 22 Days Analysis Date: 4/17/2008 4/29/2008

Concentration: 5 **μ** g/L 2 **μ** g/L

% Difference %RSD b n=3 % Difference %RSD n=3

MCAA

- 4.0 1.9

- 0.74 4.5

MBAA

- 0.10 0.68

- 5.2 2.3

Bromate 6.3 8.6

- 0.68 13 Dalapon

- 1.7 4.7 3.6 7.2
DCAA

- 2.0 7.0 3.4 9.0
BCAA

- 4.3 2.1

- 2.4 6.6

DBAA

- 9.9 12

- 4.9 11
TCAA

- 1.4 1.5 1.8 0.31
BDCAA

- 4.4 2.2

- 0.85 11
CDBAA 1.3 5.1 5.4 4.8

TBAA 1.3 4.4

- 2.0 3.3

a MCAA = m onochloroacetic acid; MBAA = monobromoacetic acid; DCAA = dichloroacetic acid; BCAA =

bromochloroacetic acid; DBAA = dibromoacetic acid; TCAA = trichloroacetic acid; BDCAA = bromodichloroacetic acid; CDBAA = chlorodibromo acetic acid; TBAA = tribromoacetic acid.

b %RSD = p ercent relative standard deviation.Page 13 

## 5. **0 Second Source Verification** 

The QCS results obtained during method development are presented in Table 4 . The PDS prepared from the second source stocks was diluted to 5 μg/L, analyzed in triplicate, and quantita ted from an initial calibration constructed using c alibration s tandards prepared from the primary source stocks.

TABLE 4

. METHOD PERFORMANCE Q UALITY C ONTROL S AMPLE RESULTS,

5 .0

- μg/L STANDARD

Analyte a Primary Source Second Source Analysis Date % Recovery R SD, b % (n=3)

MCAA Restek Ultra Scientific 2/20/2008 105 4.1

MBAA Restek Ultra Scientific 2/20/2008 98.5 1.3

Bromate Ultra Scientific AccuStandard 2/20/2008 97.2 1.7 Dalapon Ultra Scientific AccuStandard 5/14/2008 96.5 3.0
DCAA Restek Ultra Scientific 2/20/2008 107 1.2

BCAA Restek Ultra Scientific 2/20/2008 105 1.5

DBAA Restek Ultra Scientific 2/20/2008 113 1.5
TCAA Restek Ultra Scientific 2/20/2008 106 0.27
BDCAA Restek Ultra Scientific 2/20/2008 89.7 0.94
CDBAA Restek Ultra Scientific 2/20/2008 8 7.3 1.9

TBAA Restek Ultra Scientific 2/20/2008 84.4 3.8

a MCAA = m onochloroacetic acid; MBAA = monobromoacetic acid; DCAA = dichloroacetic acid; BCAA =

bromochloroacetic acid; DBAA = dibromoacetic acid; TCAA = trichloroacetic acid; BDCAA =

bromodichloroa cetic acid; CDBAA = chlorodibromoacetic acid; TBAA = tribromoacetic acid.

b RSD = r elative standard deviation.



## 6. **0 Accelerated Storage Stability Studies** 

The storage stability studies described in this section provided critical information on the perfor mance of the proposed method. Based on these results, the research team realized that a refrigerated autosampler would be required to successfully implement the direct

- inject approach. This requirement appears in Section 6 in Method 557 , and the justific ation is discussed in

Section 4 of the method

.

D alapon, CDBAA, and TBAA exhibited anomalous behavior during the initial attempts to conduct P&A studies. The group suspected that aqueous solutions of the method analytes were degrading in the warm autosamp ler. The autosampler sample tray reached temperatures of 25 °

to 2 8 ° C during operation as measured using a digital thermometer

.

The storage stability studies were designed to study the effects of storing aqueous solutions of standards and samples unde r controlled conditions. Two matrices were evaluated: 1) r eagent

w ater, and 2) Cincinnati tap water. For the first matrix, three standards (10 μg/L) prepared in

r eagent w ater and three standards (10 μg/L) prepared in r eagent w ater and preserved with NH 4 Cl

were incubated at 40 ° C for 40 hours. These six samples represented the “accelerated storagePage 14 conditions” for the r eagent w ater matrix. Three standards prepared in r eagent w ater and stored at

4 ° C served as the controls for the r eagent w ater set. For the drinking water matrix, six split aliquots of Cincinnati tap water were fortified at 10 μg/L and preserved with NH 4 Cl

. Three were

incubated at 40 ° C for 48 hours. These three samples represented the “accelerated storage condition” for the tap

- water ma trix. The other three were stored at 4 ° C. These samples represented the control condition for the tap

- water matrix.

Standards prepared in r eagent w ater and stored at 4 ° C served as the calibration standards for both matrices. The heated samples were c ooled to 4 ° C prior to analysis. Internal s tandards were added just prior to loading the samples into the autosampler and the analysis was started immediately. That is, the residency time in the warm autosampler was limited to only a few

minutes. These later steps were necessary to eliminate the variable associated with storage of the

i nternal s tandards and the samples in a warm environment. To cancel the effects of instrume nt
d rift, calibration standards, experimental conditions and controls were alter nated during the analytical sequence.

Table 5 presents the results of the accelerated storage stability studies in r eagent w ater. The analytes highlighted in bold/italic exhibited significant losses. Note that the decomposition is

more extensive in the presence of the preservative

— right

- hand column. This finding indicates that the decomposition is accelerated at lower pH or via another mechanism involving NH 4 Cl.

Table 6 presents the results of the accelerated storage stability studies in drinking wat er. As expected from previous studies published in association with the GC method, 9 all of the targets

are stable when stored at 4 ° C in the presence of the preservative

— first column in the table. However, dalapon, CDBAA, and TBAA (shown in bold/italic ) decompose when heated, but not

as much as observed in r eagent w ater (Table 5 ). This may be the result of the higher pH of drinking water

— 8.1 for this matrix

— compared with 5.8 for procedural standards prepared in

r eagent w ater

. However, the stability of a queous standards is equally important for the successful application of the method as the stability of field samples.

TABLE 5

. ACCELERATED STORAGE STABILITY STUDY IN REAGENT WATER

Analyte R eagent Water, 40 ° C, 40 Hours R eagent Water + Ammonium C hloride,

%R a % RSD b (n=3) %R % RSD (n=3)

Bromate 105 9.6 113 4.8

MBAA 93.4 1.8 92.2 0.89

MCAA 95.4 1.4 94.8 7.4 Dalapon 93.0 4.6 **45.5** 2.0

DCAA 99.1 0.79 102 0.98

BCAA 95.1 9.3 102 4.6

DBAA 100 7.3 111 4.1

TCAA 98.2 0.69 99. 1 0.63

BDCAA 96.8 3.7 95.3 3.2

CDBAA **82.0** 3.3 **68.3** 2.4

TBAA **33.4** 15 **26.9** 4.4

a %R = p ercent recovery.
b %RSD = p ercent relative standard deviation.Page 15 TABLE 6

. ACCELERATED STORAGE STABILITY STUDY IN CINCINNATI TAP

WATER (CT)

Analyte CT + Ammonium Chlor ide, 4 ° C, 48 Hours pH = 8.1 CT + NH 4 Cl 40 ° C, 48 Hours pH = 8.1

%R a % RSD b (n=3) %R % RSD (n=3)

Bromate 92.1 5.1 90.9 1.8

MBAA 93.2 3.6 93.5 1.3
MCAA 94.1 2.7 95.8 3.1 Dalapon 87.9 15 **82.9** 9.4
DCAA 95.9 2.9 97.5 2.2
BCAA 90.2 3.9 90.5 4.3

DBAA 84.6 6.0 86.9 4.0
TCAA 95.3 2.0 95.6 2.7
BDCAA 95.0 1.2 91.6 5.2
CDBAA 101 2.3 **86.7** 2.6

TBAA 100 2.0 **44.9** 4.5

a %R = p ercent recovery.
b %RSD = p ercent relative standard deviation.



## 7. **0 Chlorite and Chlorate P&A Study** 

Early in the history of the project , Dave Munch raised the question of potential interference caused by chlorite and chlorate anions, which may be present in drinking water disinfected with

ClO 2 . On May 21, 2008, Shaw conducted a P&A study using synthetic matr ix fortified at 5 μg/L

with th e method analytes, 1 mg/L chlorite, and 0.5 mg/L chlorate. These are the MCLs for these two species. Figure 1 shows the location of the chlorite ( m/z 67/51) and chlorate ( m/z 83/67)

anions relative to Method 557 analytes. Figure 2 is the conductivity tr ace corresponding to the chromatogram in Figure 1 showing the location of the chlorite and chlorate anions relative to the common anions in the synthetic sample matrix. The results of the P&A study are presented in

Table 7

.

TABLE 7

. P&A RESULTS at 5 μg/L IN THE PRESENCE OF 1 mg/L CHLORITE,

AND 0.5 mg/L CHLORATE

Analyte Recovery, % %RSD a n=8

MCAA 102 8.9

MBAA 104 1.4

Bromate 101 7.4
Dalapon 94.9 6.3

DCAA 99.0 5.1

BCAA 97.8 6.7

DBAA 92.6 8.7

TCAA 163 to 119 101 2.1

BDCAA 101 4.9

CDBAA 97.8 5.4

TB AA 107 1.5

a %RSD = relative standard deviation.Page 16 As evidenced in Figure 1, chlorite co

- elutes with MCAA. MCAA peak shape is severely degraded in the presence of chlorite and synthetic matrix. The median area response for MCAA in the eight fortified syn thetic matrix (P&A samples) is 678 compared with a median of 3080 for the five procedural calibration standards analyzed during the May 21 , 2008, sequence. The

i nternal s tandard areas in the eight P&A samples failed the method’s QC criteria. Despite the peak shape and low area response, the percent recovery and percent relative standard deviation ( RSD ) for MCAA ( Table 7 ) are well within QC limits. Evidently, the labeled i nternal s tandard (MCAA[2

- 13 C]) exactly compensates for the detrimental effects of th e chlorite anion. However,

the MRL for MCAA may be compromised if chlorite is present in the samples

.

Chlorite interference is discussed in Section 4 of the meth od. F inished water treated with ClO 2 could be analyzed using Method 552; however, the user m ust perform the method modif ication procedures ( S ect. 9.4). Shaw introduced this option because chlorite may be present at much

lower concentrations than examined during the P&A experiment described in this section . In addition, th es e P&A experiments con stitute a “worst

- case” scenario, because the synthetic matrix was used in conjunction with chlorite. The effect of chlorite on method performance was not

evaluated in d rinking water matrices.Page 17 Figure 1. Dionex AS24 column: synthetic sample matri x fortified at 5 **μ** g/L plus chlorite (1 mg/L) and chlorate (0.5 mg/L).Page 18 Figure 2. Dionex AS24 column: conductivity trace, synthetic sample matrix plus chlorite (1 mg/L) and chlorate (0.5 mg/L).~4812647.doc

— Page 19 

## 8. **0 EPA Method Performance**  **Data**

The method performance data are described in Section 1 3 of M ethod 557 and the results are presented in tabular form in Section 17 . These data were co llected using a Dionex ICS

- 3000 IC

and a Waters Quattro Premier XE ESI

- MS/MS system under the conditions listed in Section 17

of the method

. The meth od performance data include DLs and LCMRLs

. Single laboratory

P&A results are presented for four water matrices: r eagent w ater, synthetic sample matrix

, chlorinated (finished) ground water , and chlo rinated ( finished) surface water

. Dr

. Glynda Smith,

of Shaw , v alidated these results and verified transcription to the method tables as documented in

the method validation memo dated September 24, 2008 (TSC

- 3

- 0387).

During method development, MCAA exhibited low response relative to the o ther method analytes when using the m/z 93/35 transition. Because a significant percentage of the p recursor i on (m/z 93) is transmitted through the collision cell, an alternate transition ( m/z 93/93) was investigated in an attempt to improve the DL for th is analyte. However, the calculated DL for

the alternate transi tion, 0.18 μg/L , is approximately the s ame as the primary transition . For this

reason , the results collected for MCAA using the m/z 93/93 transition were not included in the

method. However, LCMRL, P&A, and DL results for MCAA using the 93/93 transition are

summa rized in the raw data packages. In general, similar performance was observed for MCAA using the 93/93 transition with no evidence of adverse matrix effects.

Throughout the project, TCAA could not be measure d using the primary transition, m/z 161/117.

A co

- eluting contaminant originating in the system interfered with this transition. Fo r this

reason
, the method performance data were collected using m /z 163/119 for TCAA. All attempt s to eliminate the interference were unsuccessful , including a tetraborate flush of the column, replacing the eluent generator cartridge, and replacing the AS24 column

.

As recognized by Dionex during development of the AS24 column resin, the presence of h igh concentrations of common anions in the sample matrix causes peak shapes to widen and retention times to shift slightly toward lower values. During the project, m uch more band broadening was observed in synthetic matrix (especially for MCAA, MBAA, and bromate) than

w as observed in the three tap waters examined (Ft. Mitchell, Cincinnati, and Las Vegas)

. These

observations indicate that synthetic matrix is “worst case” and most users will not notice a significant difference between peak profiles in r eage nt w ater and tap water. These observations

resulted in the recommendation in Section 4 of the method that matrix ion concentrations not exceed 320 mg/L chloride, 250 mg/L sulfate, 150 mg/L bicarbonate and 20 mg/L nitrate. These

are the concentrations of matrix ions in the synthetic matrix. The figures in the method clearly illustrate the effect of high ionic strength on peak width when approaching these concentrations.

The analyst is instructed to verify performance in synthetic matrix during the Initia l Demonstration of Capability (IDC), and verify e lution/ d ivert w indows on a daily basis in synthetic matrix fortified with the method analytes (M557, Sect. 10.2.5)

, to ensure that d ivert

w indows are properly set to compensate for the effects of high

- ionic

- strength matrices.~4812647.doc

— Page 20 

## 9

**. 0 Second**  **Laboratory Results**

Method 557 was independently validated by Ms. Rebecca Col gate at the Chemistry Division, Water Quality Laboratory, SNWA

, Henderson, N evada 89015. Her contact information is as follows :

R. J. Colgate, Sc ientist II Rebecca.Colgate@lvvwd.com

702

- 856

- 3527

SNWA used a Dio nex ICS

- 3000 IC coupled to an MDS/Sciex API

- 4000 ESI

- MS/MS . They

obtained the method i nternal s tandards as solutions in MtBE from Dionex. A chromatography vendor supplied the HAA method analytes as a certified mixed standard in MtBE.

Ms. Colgate completed the IDC, performed an LCMRL study for the HAA9 targets, and

cond ucted a P&A study o n Las Vegas tap water. The LCMRL results are presente d in Table 8

, along with the LCMRL results that Shaw obtained at the TSC laboratories in Cincinnati. SNWA

conducted P&A studies in three matrices: tap water ( Table 9 ), r eagent w ater (Table 1 0 ), and synthetic sample matrix (Table 1 1 ). An extracted ion ch romatogram of a Las Vegas tap

- water sample fortified at 10 μg/L during the P&A study is presented in Figure 3. Note the peak tailing evident in this chromatogram, which Shaw did not generally observe. Shaw experienced tailing peaks at one point during co llection of the method performance data; however, changing the precolumn resolved this problem.

While conducting the LCMRL analyses, SNWA limited the calibration range in violation of the

stand ard operating procedure ( SOP ) requirements. SNWA calibrated u p to 5 .0 μg/L during the LCMRL study, but used a calibration range of 0.5 0 to 30 μg/L during the IDC and during the

tap

- water P&A study. The Shaw LCMRL SOP (QA

- 011 ) was sent to them ; however, this requirement was not specifically called out in the associa ted e

- mail , or by telephone.

SNWA sent spreadsheets with the raw data results and the calculated study results. Alan Zaffiro reviewed and summarized the QC results associated with the second laboratory studies. The QC

result summaries were added to the sp readsheets provided by SNWA. During the analytical sequences for all the second laboratory studies referenced above, the i nternal s tandard areas,

c ontinuing c alibration c hecks , and l aboratory r eagent b lank s met the QC acceptance criteria specified in Se ction 9 of the method. There were no outliers.~4812647.doc

— Page 21 TABLE 8

. SOUTHERN NEVADA WATER AUTHORITY IC/ESI

- MS/MS LOWEST
CONCENTRATION MRLs a

Analyte LCMRL b Fortification Levels (μg/L) c

- Shaw LCMRL Fortification Levels (μg/L)

– SNWA Shaw
LCMRL (μg/L) SNWA
LCMRL (μg/L ) d

Monochloroacetic

acid 0.10, 0.25, 0.375, 0.50, 0.75, 1.0, 1.25, 1.5, 1.75,

2.0 0.025, 0.05, 0.10, 0.20, 0.50, 1.0, 2.0, 5.0 0.58 0.27

Monobromoacetic

acid 0.050, 0.10, 0.25, 0.375, 0.50, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0 0.025, 0.05, 0.10, 0.20, 0.50, 1 .0, 2.0, 5.0 0.19 0.12

Bromate 0.025, 0.050, 0.10, 0.25, 0.375, 0.50, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0 Not analyzed 0.042 Not analyzed

Dalapon 0.25, 0.375, 0.50, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0 Not analyzed 0.41 Not analyzed

Dichloroacetic acid 0.025, 0. 050, 0.10, 0.25, 0.375, 0.50, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0 0.025, 0.05, 0.10, 0.20, 0.50, 1.0, 2.0, 5.0 0.13 0.052

Bromochloroacetic

acid 0.10, 0.25, 0.375, 0.50, 0.75, 1.0, 1.25, 1.5, 1.75,

2.0 0.025, 0.05, 0.10, 0.20, 0.50, 1.0, 2.0, 5.0 0.16 0.050

Dibromoacetic acid 0.025, 0.050, 0.10, 0.25, 0.375, 0.50, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0 0.010, 0.025, 0.05, 0.10, 0.20, 0.50, 1.0, 2.0, 5.0 0.062 0.043

Trichloroacetic acid 0.10, 0.25, 0.375, 0.50, 0.75, 1.0, 1.25, 1.5, 1.75,

2.0 0.025, 0.05, 0.10, 0.20

, 0.50, 1.0, 2.0, 5.0 0.25 0.22

Bromodichloroacetic

acid 0.050, 0.10, 0.25, 0.375, 0.50, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0 0.025, 0.05, 0.10, 0.20, 0.50, 1.0, 2.0, 5.0 0.19 0.067

Chlorodibromoacetic

acid 0.050, 0.10, 0.25, 0.375, 0.50, 0.75, 1.0, 1.25, 1.5

, 1.75, 2.0 0.025, 0.05, 0.10, 0.20, 0.50, 1.0, 2.0, 5.0 0.080 0.062

Tribromoacetic acid 0.10, 0.25, 0.375, 0.50, 0.75, 1.0, 1.25, 1.5, 1.75,

2.0 0.010, 0.025, 0.05, 0.10, 0.20, 0.50, 1.0, 2.0, 5.0 0.27 0.025

a IC/ESI = ion chromatography/electrospray io nization ; MRL = minimum reporting level.

b LCMRL = l owest

- concentration, minimum reporting level

.

c μ g/L = m icrograms per liter.

d Calibration range: low to 5.0 μg/L; this is a violation of standard operating procedure requirement to

calibrate in the norm al range. SNWA used a 0.5

- to 30

- μg/L calibration range for the i nitial

d emonstration

- of

- capability and precision

- and

- accuracy studies.~4812647.doc

— Page 22 TABLE 9

. SOUTHERN NEVADA WATER AUTHORITY (SNWA) PRECISION AND ACCURACY RESULTS FOR TAP

WATER FORTIFIED AT 10 μg/L a ( n = 9) b

MCAA MBAA DCAA BCAA DBAA TCAA BDCAA CDBAA TBAA

M ean , unfortified sample c 2.3 0.86 16 9.7 4.5 11 4.7 2.5 0.39

R elative standard deviation (%) 4.8 6.6 1.9 5.1 2.4 1.8 2.2 2.3 3.3

Mean % r ecovery 106 105 101 91.5 100 105 111 114 111

a **μ** g/L = m icrogr ams per liter.

b Surface water physical parameters: pH = 7.79; hardness = 310 milligrams/liter (mg/L) (as CaCO 3 ); free chlorine = 1.85 mg/L. These values

are taken from the SNWA RMWTF Finished Water Inorganics report (September 2008).

c Recoveries correc ted for native levels in the unfortified matrix.

TABLE 10

. SOUTHERN NEVADA WATER AUTHORITY (SNWA) PRECISION AND ACCURACY RESULTS FOR

REAGENT WATER FORTIFIED AT 10 μg/L a ( n = 9)

MCAA MBAA DCAA BCAA DBAA TCAA BDCAA CDBAA TBAA

R elative standard deviation (%) 4.8 1.7 1.7 7.1 9.3 4.8 6.9 5.8 7.1

Mean % r ecovery 96.2 108 100 101 103 102 102 102 110

a **μ** g/L = m icrograms per liter.

TABLE 1 1

. SOUTHERN NEVADA WATER AUTHORITY (SNWA) PRECISION AND ACCURACY RESULTS FOR
SYNTHETIC MATRIX FORTIFIED AT 10 μg/L a ( n = 9)

MCAA MBAA DCAA BCAA DBAA TCAA BDCAA CDBAA TBAA Relative standard deviation (%) 4.0 2.5 2.7 3.1 3.3 2.7 2.3 2.9 4.4 Mean % recovery 99.7 104 99.7 94.0 99.8 101 88.3 92.4 99.5

a **μ** g/L = m icrograms per liter.~4812647.doc

— Page 23 Figure 3. Las Vegas tap water f ortified at 10 micrograms per liter ( μg/L ) and analyzed on the AS24 column at the SNWA laboratory. Peak identification: 1) MCAA and MCAA[2

- 13 C], 2) MBAA and MBAA[1

- 13 C], 3) dalapon, 4) DCAA and DCAA[2

- 13 C], 5) BCAA, 6) DBAA, 7) TCAA and TCAA[2

- 13 C], 8) BD CAA, 9) CDBAA, 10) TBAA.~4812647.doc

— Page 24 

## 10. **0 References** 

1. U.S. Environmental Protection Agency . January 2006. National Primary Drinking Water Regulations: Stage 2 Disinfectants and Disinfection Byproducts Rule; Final Rule.

40 CFR Parts 9, 141, and 142.

2. U.S. Environ mental Protection Agency Office of Ground Water and Drinking Water. EPA Methods 552.1, 552.2, and 552.3

3. American Public Health Association, the American Water Works Association, and the

Water Environment Federation. Standard Methods 6251 B and 6251 B

- 94

. Updated annually.

4. Barron, L., and Paull , B

. Simultaneous Determination of Trace Oxyhalides and Haloacetic Acids Using Suppressed Ion Chromatography

- Electrospray Mass Spectrometry. Talanta 69 (2006) 621

- 630.

5. Barron, L., and Paull , B

. Using Ion Chr omatography to Monitor Haloacetic Acids in Drinking Water: A Review of Current Technologies. J. of Chromatography A

, 1046 (2004) 1

- 9.

6. U.S. Environmental Protection Agency

. July 2002

. National Primary Dr inking Water Regulations: List of Contaminants an d their Maximum Concentration Levels (MCLs),

EPA 816

- F

- 02

- 013, [www.epa.gov/safewater/mcl.html#mcls]

7. Winslow, S. D.; Pepich, B. V.; Martin, J. J.; Hallberg, G. R.; Munch D. J.; Frebis, C. P.; Hedrick, E. J.; and Krop, R. A. Statistical Procedures for Det ermination and Verification of Minimum Reporting Levels for Drinking Water Methods. Environ. Sci. Technol

. 2006; 40, 281

- 288.

8. Glaser, J. A.; Foerst, D. L.; McKee, G. D.; Quave, S. A.; and Budde, W. L. Trace Analyses for Waste waters. Environ. Sci. Tec hnol. 1981 ; 15, 1426

- 1435.

9. Pepich, B. V.; Domino, M. M.; Munch, D. J. ; and Fair, P. S. Validating Sample

Preservation Tech niques and Holding Times for the Approved Compliance Monitoring

Methods for Haloacetic Acids under the U.S. EPA’s Stage 1 D/DBP Rul e

. Wat. Res., 38 (2004) 895

- 902

.