## Pa ge 1 of 6 Office of Ground Water and Drinking Water

November 19, 2012

MEMORANDUM

SUBJECT: Basis for Expedited Approval of EPA Method 524. 4

FROM: Glynda Smith, Chemist

Steve Wendelken, Chemist

Technical Support Center

TO: The Record

Research is comp lete on EPA Method 524. 4 for determination of volatile organic

contaminants in drinking water. This memo documents the comp arison of Method 524. 4

to EPA M ethod 524.2 which was promulgated for the same contaminants (see Table 1)

. It also compares Method 5 24.4 to EPA Method 524.3 which was approved via expedited

method approval action (74 FR 38348). Method 524.3 was evaluated against EPA

M ethod 524.2 and found to be equally as effective as the approved method

.

EPA has established Maximum Contaminant Lev els (MCLs) for the 29 analytes listed in

Table 1. T he performance characteristics of EPA Method 524. 4 were compared to the

characteristics of the approved method 524.2 for the se regulated analytes. The

performance characteristics presented in this memo i nclude detection limit as defined in

40 CFR Part 136 Appendix B

, and comparative precision and accuracy data

.

Method 524. 4 features most of the same elements that were incorporated in the 524.3

revision: the list of analytes includes fuel oxygenates and volatile organic compounds

(VOCs) amenable to purge

- and

- trap from the preliminary Contaminant Candidate List 3

(CCL3). It employs ascorbic acid and maleic acid ( a common food preservative ) to

dechlorinate and preserve samples, eliminating the requiremen t to ship a hazardous

reagent (hydrochloric acid) to the field

. Storage stability was demonstrated under the

preservation conditions developed for Method 524.3, and these are documented in the

524.4 revision

. The primary difference between methods 524.3 and 524.4 lies in the

purge gas. The cost of helium continues to rise and Method 524.4 was develop ed using

less expensive nitrogen to purge the analytes from the water sample instead of helium

.

Both methods 524.3 and 524.4 include the option for operatin g the mass spectrometer in

selected ion monitoring (SIM) mode to achieve low er detection limits

. As opposed to

Method 524.3, the Method 524.4 SIM data failed to meet the detection limits required for

determining monitoring frequencies for 1,2

- dibromo

- 3

- ch loropropane (DBCP) and 1,2

- dibromoethane (EDB). In order to be considered for expedited approval, methods must

be equally as effective as those approved in the regulations

. As cited in 40 CFR

141.24(e)(1), the approved methods for DBCP and EDB are 504.1 and 551.1. Relative to

## Pa ge 2 of 6 those approved methods, 524.4 cannot be considered equally as effective in terms of

meeting the detection criteria. Therefore, methods 524.4 cannot be approved for

compliance monitoring of DBCP or EDB.

Table 2 provides a compar ison of detection limits excerpted f rom the method

performance section s of the approved method 524.2, along with methods 524.3 and

524.4

. The detection levels for Method 524. 4 ( both full scan and SIM ) are similar to

those obtained by the approved method

, except as described above for EDB and DBCP

. The Code of Federal Regulations (40 CFR 141.24 (f)( 1 7)) requires laboratories to meet a

minimum detection limit (MDL) of 0.5 μ g/L for the contaminants listed in 40 CFR

141.61 (a)

, (chemicals generally referred t o as volatile organic contaminants

- VOCs) in

order to be certified . It is demonstrated in Table 2 that this requirement is easily met

using Method 524. 4 for all of the regulated VOCs. R egulatory detection level s for

determining monitoring frequencies (n ot laboratory certification) for DBCP and EDB are

published at 40 CFR 141.24(h)(18)

. As discussed previously, the reported data indicate

that t hese levels are not met using Method 524. 4

. Minimum Reporting Level (MRL)

requirements for laboratory certifica tion and reporting purposes are published at 40 CFR

141.131(b)(2)(iv) for the Trihalomethanes ( chloroform, bromodichloromethane,

dibromochloromethane, and bromoform )

. These levels are easily met using Method

524. 4

.

A comparison of precision and accuracy data obtained in full scan mode for the approved

method 524.2, M ethod 524.3 , and Method 524.4 are presented in Table 3. The data were

obtained by fortifying reagent water samples with the contaminants and performing

replicate analyses. The accuracy (as sho wn by percent Recovery

— %R) and precision

(relative standard deviation

— RSD) data for Method 524. 4 are comparable to the other

two methods.

In summary, t he performance characteristics of EPA Method 524. 4 are within the range

of the characteristics obtain ed using the promulgated method for the same contaminant s

. Therefore, EPA Method 524. 4 is equally as effe ctive as the promulgated method for

determining the concentra tions of VOCs and TTHM regulated in drinking water

.

## Pa ge 3 of 6 Table 1. Method 524.4 Analytes Regula ted in Drinking Water, Maximum Contaminant Levels, and Approved Methods

.

Approved

Method Method 524.3

– Operation

Mode Method 524.4

– Operation

Mode

Analyte CAS No. MCL, μ g/L a 524.2

Rev 4.1 Full Scan Selected Ion

Monitoring Full Scan Selected Ion

M onitoring d

1 1,1,1

- trichloroethane 71

- 55

- 6 200 X X X X

2 1,1,2

- trichloroethane 79

- 00

- 5 5 X X X X

3 1,1

- dichloroethene 75

- 35

- 4 7 X X X X

4 1,2,4

- trichlorobenzene 120

- 82

- 1 70 X X X X

5 1,2

- dibromo

- 3

- chloropropane 96

- 12

- 8 0.2 X X

6 1,2

- dibromoeth ane 106

- 93

- 4 0.05 X X

7 1,2

- dichlorobenzene 95

- 50

- 1 600 X X X X

8 1,2

- dichloroethane 107

- 06

- 2 5 X X X X

9 1,2

- dichloropropane 78

- 87

- 5 5 X X X X

10 1,4

- dichlorobenzene 106

- 46

- 7 75 X X X X

11 benzene 71.43

- 2 5 X X X X

12 bromodichloromethane 75

- 27

- 4 80 TTHM b X X X X

13 bromoform 75

- 25

- 2 80 TTHM b X X X X

14 carbon tetrachloride 56

- 23

- 5 5 X X X X

15 chlorobenzene 108

- 90

- 7 100 X X X X

16 chloroform 67

- 66

- 3 80 TTHM b X X X X

17 cis

- 1,2

- dichloroethene 156

- 59

- 2 70 X X X X

18 dibromochlor omethane 124

- 48

- 1 80 TTHM b X X X X

19 ethylbenzene 100

- 41

- 4 700 X X X X

20 methylene chloride 75

- 09

- 2 5 X X X X

21 m

- xylene (co

- elutes w/para) 108

- 38

- 3 10,000 c X X X X

22 o

- xylene 95

- 47

- 6 10,000 c X X X X

23 p

- xylene (co

- elutes w/meta) 106

- 42

- 3 10,000 c X X X X

24 styrene 100

- 42

- 5 100 X X X X

25 tetrachloroethene 127

- 18

- 4 5 X X X X

26 toluene 108

- 88

- 3 1000 X X X X

27 trans

- 1,2

- dichloroethene 156

- 60

- 5 100 X X X X

28 trichloroethene 79

- 01

- 6 5 X X X X

29 vinyl chloride 75

- 01

- 4 2 X X X X

a. MCL = Maximum Contaminant Level; 40 CFR 141.61(a) for volatile organic contaminant MCLs; 40 CFR 141.61(c) for 1,2

- dibromo

- 3

- chloropropane (DBCP) and 1,2

- dibromoethane

(EDB) MCLs; and 40 CFR 141.64(b) for TTHM MCL.

b. TTHM = T otal Trihalomethanes (sum of chloroform, bromodichloromethane, dibromochloromethane, and bromoform)

c. Regulated as x ylenes ( total ) (sum of o

- xylene, m

- xylene, and p

- xylene)

d. Additional multi

- lab Selected Ion Monitoring data obtained for Method 524.4 (DLs and LCMRLs)

## Pa ge 4 of 6 Table 2. Dete ction Limit Comparison between Approved Method 524.2, Expedited Approval Method 524.3 and Method 524. 4 for

Purgeable Organic Compounds Regulated in Drinking Water. (All concentrations are μg/L.)

Analyte Regulatory

Detection

Limit a 524.2

Rev 4.1

MDLs b 5 24.3

Full Scan d

MDLs/LCMRLs c 524.3

SIM e

MDLs/LCMRLs 524.4

Full Scan g

MDLs/LCMRLs 524. 4

SIM h

M D Ls/LCMRLs 524.4 SIM i

Multi

- Lab

MRLs

1 1,1,1

- trichloroethane 0.5 0.08 0.026 / 0.076

--- 0.060/0.17 0.009/0.039

---

2 1,1,2

- trichloroethane 0.5 0.10 0. 048 / 0.14

--- 0.048/0.38 0.010/0.029

---

3 1,1

- dichloroethene 0.5 0.12 0.049 / 0.092

--- 0.14/0.18 0.009/0.061

---

4 1,2,4

- trichlorobenzene 0.5 0.04 0.013 / 0.053

--- 0.07 1 /0.15 0.013/0.030

---

5 1,2

- dibromo

- 3

- chloropropane 0.02 0.26 f 0.063 f / 0.27 f 0.0016 / 0.0017 0.15 f /0.44 f 0. 0 33 f /0. 0 69 f 0.060 f

6 1,2

- dibromoethane 0.01 0.06 f 0.018 f / 0.059 f 0.0010 / 0.0041 0.090 f /0.13 f 0.023 f /0.048 f 0.020 f

7 1,2

- dichlorobenzene 0.5 0.03 0.019 / 0.066

--- 0.056/0.14 0.013/0.025

---

8 1,2

- dichloroeth ane 0.5 0.06 0.025 / 0.051

--- 0.027/0.23 0.012/0.029 0.017

9 1,2

- dichloropropane 0.5 0.04 0.018 / 0.065

--- 0.088/0.17 0.011/0.043 0.067

10 1,4

- dichlorobenzene 0.5 0.03 0.015 / 0.065

--- 0.029/0.19 0.012/0.026

---

11 b enzene 0.5 0.04 0.017 / 0.030

--- 0.028/0.11 0.012/0.022 0.055

12 bromodichloromethane 1.0 0.08 0.014 / 0.073

--- 0.081/0.19 0.011/0.027

---

13 bromoform 1.0 0.12 0.040 / 0.15

--- 0.14/0.26 0.008/0.021

---

14 carbon tetrachloride 0.5 0.21 0.044 / 0.098

--- 0.073/0.14 0.008/0.033 0.018

15 chlorobenzene 0.5 0.04 0.019 / 0.15

--- 0.050/0.20 0.009/0.036

---

16 chloroform 1.0 0.03 0.025 / 0.054

--- 0.070/0.16 0.015/0.032

---

17 cis

- 1,2

- dichloroethene 0.5 0.12 0.042 / 0.12

--- 0.083/0.21 0.037/0.040

---

18 dibromochloromethane 1.0 0.05 0.0 27 / 0.14

--- 0.10/0.23 0.006/0.016

---

19 ethylbenzene 0.5 0.06 0.010 / 0.085

--- 0.026/0.15 0.009/0.013

---

20 methylene chloride 0.5 0.03 0.14 / 0.25

--- 0.18/0.15 NA

---

21 m

- xylene (co

- elutes w/para) 0.5 0.05 0.020 / 0.069

--- 0.11/0.30 0.020/0.17

---

22 o

- xylene 0.5 0.11 0.010 / 0.039

--- 0.11/0.26 0.016/0.037

---

23 p

- xylene (co

- elutes w/meta) 0.5 0.13 0.020 / 0.069

--- 0.11/0.30 0.020/0.17

---

24 styrene 0.5 0.04 0.011 / 0.11

--- 0.033/0.20 0.012/0.018

---

25 t etrachloroethene 0.5 0.14 0.036 / 0.081

--- 0.059/0.27 0.011/0.025 0.018

26 toluene 0.5 0.11 0.024 / 0.053

--- 0.031/0.13 0.009/0.034

---

27 trans

- 1,2

- dichloroethene 0.5 0.06 0.050 / 0.098

--- 0.12/0.29 0.014/0.028

---

28 trichloroethene 0.5 0.19 0.035 / 0.091

--- 0.078/0.13 0.012/0.0 37 0.020

29 vinyl chloride 0.5 0.17 0.029 / 0.092

--- 0.063/0.15 0.007/0.048 0.026

a. Method detection limit (MDL) requirement for laboratory certification purposes published at 40 CFR 141.24(f)(17) for volatile organic contaminants; regulatory detection l evel for

determining monitoring frequencies published at 40 CFR 141.24(h)(18) for 1,2

- dibromo

- 3

- chloropropane and 1,2

- dibromoethane ; Minimum Reporting Level (MRL) requirement s for

laboratory certification and reporting purposes published at 40 CFR 141.131( b)(2)(iv) for chloroform, bromodichlorometh ane, dibromochloromethane, and bromoform.

b. MDL calculated according to procedure published at 40 CFR 136 Appendix B. Data sources: Method 524.2 Table 4

c. Lowest Concentration Minimum Reporting Level (LCMRL) calculate d according to the procedure described in Winslow , S. D. et.al. Statistical Procedures for Determination and

Verification of Minimum Reporting Levels for Drinking Water Methods. Environ. Sci. Technol . 2006; 40, 281

- 288.

d. M ethod 524.3 Table 6

## Pa ge 5 of 6 e. Method 524.3 Table 10

f. Method fails to meet regulatory requirement for this contaminant

g. Method 524.4 Table 6

h. Method 524.4 Table 10

i. EPA Method 524.4 Multi

- Lab SIM MRL d etermination for possible inclusion in a c arcinogenic VOC group ; inter nal communication



### Table 3. Precision and Accuracy Comparison in Fortified Reagent Water between Approved Method 524.2, Expedited Method 524.3

, and Method 524.4 using Full Scan MS Detection

Analyte 524.2 Rev. 4.1 a 524.3

- Full Scan e 524.4

– Full Scan f

C b %R c RSD d C b %R c RSD d C b %R c RSD d

1 1,1,1

- trichloroethane 0.5

- 10 98 8.1 1.0 98.0 10 1.0 91.1 6.3

2 1,1,2

- trichloroethane 0.5

- 10 104 7.3 1.0 101 7.3 1.0 101 8.5

3 1,1

- dichloroethene 0.1

- 10 94 6.7 1.0 94.8 9.0 1.0 9 3.2 5. 3

4 1,2,4

- trichlor obenzene 0.5

- 10 108 8.3 1.0 95.6 7.2 1.0 91.9 2.1

5 1,2

- dibromo

- 3

- chloropropane 0.5

- 10 83 19.9 1.0 99.3 8.2 1.0 90.9 7.1

6 1,2

- dibromoethane 0.5

- 10 102 3.9 1.0 101 7.9 1.0 89.5 4.5

7 1,2

- dichlorobenzene 0.1

- 10 93 6.2 1.0 96.3 8.3 1.0 96.6 3.4

8 1,2

- dic hloroethane 0.1

- 10 95 5.4 1.0 101 7.4 1.0 102 4.5

9 1,2

- dichloropropane 0.1

- 10 97 6.1 1.0 99.6 8.9 1.0 92.4 6.0

10 1,4

- dichlorobenzene 0.2

- 20 103 6.4 1.0 95.8 7.5 1.0 97.2 3.3

11 benzene 0

. 1

- 10 97 5.7 1.0 99.4 7.8 1.0 93.6 4.6

12 bromodichloromethane 0 .1

- 10 95 6.1 1.0 97.1 8.7 1.0 97.1 3.7

13 bromoform 0.5

- 10 101 6.3 1.0 92.0 8.1 1.0 91.0 3.9

14 carbon tetrachloride 0.5

- 10 84 8.8 1.0 93.9 7.6 1.0 92.4 3.9

15 chlorobenzene 0.1

- 10 98 5.9 1.0 99.2 7.2 1.0 93.4 3.3

16 chloroform 0.5

- 10 90 6.1 1.0 99.4 5 .3 1.0 97.3 4.3

17 cis

- 1,2

- dichloroethene 0.5

- 10 101 6.7 1.0 99.5 8.9 1.0 94.2 5.6

18 dibromochloromethane 0.1

- 10 92 7.0 1.0 95.0 7.9 1.0 95.7 3.7

19 ethylbenzene 0.1

- 10 99 8.6 1.0 95.9 9.2 1.0 93.8 3.8

20 methylene chloride 0.1

- 10 95 5.3 1.0 106 5.6 1 .0 84.5 15

21 m

- xylene (co

- elutes w/para) 0.1

- 10 97 6.5 1.0 98.2 9.2 1.0 93.3 2.9

22 o

- xylene 0.1

- 31 103 7.2 1.0 98.3 8.3 1.0 94.3 2.7

23 p

- xylene (co

- elutes w/meta) 0.5

- 10 104 7.7 1.0 98.2 9.2 1.0 93.3 2.9

24 styrene 0.1

- 100 102 7.2 1.0 95.5 8.8 1.0 9 5.3 3.3

25 tetrachloroethene 0.5

- 10 89 6.8 1.0 98.8 8.8 1.0 87.2 5.8

26 toluene 0.5

- 10 102 8.0 1.0 99.2 9.6 1.0 92.0 6.5

27 trans

- 1,2

- dichloroethene 0.1

- 10 93 5.6 1.0 100 6.8 1.0 104 3.2

28 trichloroethene 0.5

- 10 90 7.3 1.0 99.6 7.9 1.0 103 4.9

29 vin yl chloride 0.5

- 10 98 6.7 1.0 94.9 8.1 1.0 106 6.0

a. M e thod 524.2 data

- Table 4

b. C = Concentration (μg/L) fortified into reagent water

## Pa ge 6 of 6 c. %R = % Recovery

d. RSD = relative standard deviation

e. Method 524.3 data

- Table 7

f. Method 524.4 data

– Table 7