Page 1 of 10

Office of Ground Water and Drinking Water

January 23, 2012

MEMORANDUM

SUBJECT: Basis for Expedited Approval of EPA Method 525.3

FROM: Jean Munch and Paul Grimmett

Office of Research and Development, National Exposure Research Laboratory

Glynda Smith

Standards and Risk Management Division, Technical Support Center

TO: The Record

Research has been completed on EPA’s revision of EPA Method 525.2 for semivolatile organic 

contaminants in drinking water. This memo documents the comparison of EPA Method 525.3 to the 

approved method. It also provides the background information on why EPA is approving this method 

using the expedited methods approval process.

EPA has established Maximum Contaminant Levels (MCLs) as cited at 40 CFR 141.61(c) for the following

seventeen contaminants:

Contaminant MCL (μg/L)

Alachlor 2

Atrazine 3

Polychlorinated biphenyls (PCBs – as 

decachlorobiphenyl)

*

0.5

Benzo[a]pyrene 0.2

Chlordane 2

Di(2-ethylhexyl) adipate 400

Di(2-ethylhexyl) phthalate 6

Endrin 2

Lindane (HCH-γ) 0.2

Heptachlor 0.4

Heptachlor epoxide 0.2

Hexachlorobenzene 1

Hexachlorocyclopentadiene 50

Methoxychlor 40

Pentachlorophenol 1

Simazine 4

Toxaphene 3

* In the table at 40 CFR 141.61(c), only the term “polychlorinated biphenyls” is listed with a MCL 

level of 0.5 μg/L. However, 40 CFR 141.24(h)(13)(iii) specifies “compliance with the PCB MCL 

shall be determined based upon the quantitative results of analyses using Method 508A.” EPA 

Method 508A converts PCBs to decachlorobiphenyl, thus the qualifier shown in the table above.
Page 2 of 10

EPA approved Method 525.2 for these contaminants through the formal notice-and-comment 

rulemaking process. As a result, the benchmark for any alternative methods was established when 

Method 525.2 was promulgated. The performance characteristics of the revised method, EPA Method 

525.3, were compared to the characteristics of the approved method for each of these regulated 

analytes. The performance characteristics presented in this memo to the record include the detection 

limit as defined in 40 CFR Part 136 Appendix B, and precision and accuracy determinations.

It has been over fifteen years since Method 525.2 was published; revision was warranted in order to 

take advantage of newer solid phase extraction sorbents, to evaluate performance using selected ion 

monitoring (SIM) in addition to full scan mass spectral detection, and to evaluate alternate sample 

preservatives. Method 525.3 achieved several significant goals, including:

• Use of solid preservation reagents (ascorbic acid, EDTA, and potassium dihydrogen citrate),

which eliminates the requirement to ship a hazardous liquid reagent (hydrochloric acid) to the 

field. Storage stability was demonstrated under the preservation conditions developed for 

Method 525.3 and is documented in the method.

• Method 525.3 includes the option for operating the mass spectrometer in SIM mode. The 

enhanced sensitivity provided by SIM-mode detection facilitates detection of contaminants with 

low regulatory detection limits. For example, SIM-mode detection is needed to meet 

toxaphene’s drinking water monitoring trigger of 1 μg/L [40 CFR 141.24(h)(18)] and MCL of 

3 μg/L [40 CFR 141.61(c)].

• Method 525.3 provides performance data for multiple solid phase extraction media (disks and 

cartridges) and GC/MS systems. Method development was conducted across two laboratories 

and validated in multi-laboratory studies, including two commercial laboratories and a drinking 

water utility lab. 

• Method 525.3 provides more guidance for handling the data reduction associated with the 

multi-component analytes (toxaphene, PCBs and chlordane).

• Method 525.3 incorporates the option of using matrix-matched calibration standards (extracted 

reagent water) to minimize matrix-induced effects, especially if low concentrations need to be 

determined for analytes that are susceptible to matrix effects.

• Method 525.3 incorporates fourteen polychlorinated biphenyl (PCB) congeners that are 

representative of the major components (by weight percent) of Aroclors 1016, 1221, 1232, 

1242, 1248, 1254, and 1260. Analyzing for the specific congeners as described in Method 525.3 

permits screening for Aroclor contamination without requiring complex pattern recognition.

• Method 525.3 corrects a QC issue. In the approved method, internal standards and surrogates 

are added prior to the extraction step. In essence, they are all extraction surrogates. An

internal standard is added for the purpose of being a reference for calibration and minimizing 

the run-to-run variability in detector response. If the internal standard is added prior to the 

extraction step, it can be lost as part of the extraction procedure. Thus, in Method 525.3, the 
Page 3 of 10

surrogates are added prior to extraction and the internal standards are added to the final 

extract.

The Method 525.3 performance data were collected on GC/MS systems equipped with quadrupole mass 

spectrometers. Thus, the comparative data in the following tables demonstrate equivalence relative to 

the performance data published in the approved method that was also collected with a quadrupole 

mass spectrometer.

Table 1 provides a comparison of detection limits obtained from the method performance sections of 

the approved Method 525.2 and Method 525.3. The detection levels for Method 525.3 using full scan 

MS detection are similar to and, in many cases, superior to those obtained for the approved method. 

Regulatory detection levels for determining monitoring frequencies for the semivolatile organic 

contaminants are published at 40 CFR 141.24(h)(18). 

A comparison of precision and accuracy data for approved Method 525.2 and Method 525.3 are 

presented in Table 2. The data were obtained by fortifying reagent water samples with the 

contaminants and performing replicate analyses. Except where noted, the fortification level used to 

obtain the data for Method 525.3 was half the level used for Method 525.2 (0.25 μg/L vs. 0.5 μg/L). As 

the data in Table 2 indicate, the accuracy (reported as percent recovery) and precision (relative standard 

deviation) data for Method 525.3 are comparable to those obtained with the approved method.

Table 3 provides additional precision and accuracy data for Method 525.3 when the mass spectrometer 

is operated in SIM mode. Except as noted, the fortification level for the contaminants was ten times 

lower (0.025 μg/L) than the level used for the full range mass spectral analyses. Two solid phase 

extraction sorbents were selected to demonstrate the enhanced sensitivity and overall method 

performance using SIM mode detection. Table 3 also provides SIM mode precision and accuracy data 

for toxaphene using additional solid phase extraction sorbents. Toxaphene data was not generated in 

full scan MS mode due to insufficient sensitivity relative to its regulatory requirements.

As the data indicate, the method performance characteristics of EPA Method 525.3 are equivalent to 

the characteristics obtained using the promulgated method for the same contaminants. Therefore, EPA 

Method 525.3 is equally effective as the approved Method 525.2 for determining the concentrations of 

17 regulated semivolatile organic contaminants. 
Page 4 of 10

Table 1. Detection Limit Comparison between Approved Method 525.2 and Method 525.3. All concentrations are listed as μg/L.

Contaminant

Regulatory Limit

40 CFR 141.24 

(h)(18)c

MDLs published in Method 

525.2a

MDLs/LCMRLs published in Method 525.3a,b

Full Scan Operating Mode SIM Mode

C18 Cartridge C18 Disk Oasis HLB 

Cartridge

StyreneDivinyl 

Benzene Disk

Oasis HLB 

Cartridge

Alachlor 0.2 0.16 0.087 0.035/0.25 0.0084/0.097 0.0045/0.016

Atrazine 0.1 0.078 0.065 0.030/0.29 0.010/0.086 0.0062/0.023

Benzo[a]pyrene 0.02 0.032 0.11 0.043/0.18 0.035/0.11 0.0069/0.036

cis-Chlordane (alpha) 0.2 0.12 0.061 0.10/0.33 0.0094/0.068 0.0016/0.0073

trans-Chlordane (gamma) 0.2 0.11 0.050 0.027/0.28 0.010/0.043 0.0028/0.0097

Chlordane (trans-nonachlor) 0.2 0.22 0.11 0.035/0.35 0.0062/0.049 0.0029/0.0061

Di(2-ethylhexyl) adipate 0.6 0.09 NDd 0.079/0.38 0.013/0.083 ND/0.38

Di(2-ethylhexyl) phthalate 0.6 ND ND ND/0.29 0.020/0.40 ND/0.43

Endrin 0.01 0.29 0.31 0.045/0.40 0.033/0.12 0.0081/0.014

Lindane (HCH-γ) 0.02 0.15 0.12 0.036/0.24 0.014/0.078 0.0040/0.031

Heptachlor 0.04 0.15 0.14 0.034/0.27 0.0032/0.029 0.0034/0.010

Heptachlor epoxide 0.02 0.058 0.093 0.039/0.11 0.0053/0.063 0.0026/0.017

Hexachlorobenzene 0.1 0.13 0.12 0.016/0.40 0.0094/0.087 0.0092/0.014

Hexachlorocyclopentadiene (HCCPD) 0.1 0.072 0.16 0.012/0.24 0.0066/0.084 0.0055/0.014

Methoxychlor 0.1 0.077 0.033 0.024/0.23 0.0064/0.061 0.0025/0.021

Pentachlorophenol 0.04 ND 0.89 0.060/0.56 0.069/0.16 0.047/0.068

Simazine 0.07 0.15 0.18 0.023/0.12 0.0059/0.083 0.010/0.048

Toxaphene 1 NAe NA NA NA 0.32/1.4

PCB congeners (IUPAC No.):

2-chlorobiphenyl (1) --- 0.086 0.023 0.021/0.14 0.0061/0.054 0.0024/0.0080

4-chlorobiphenyl (3) --- NA NA 0.019/0.24 0.0059/0.065 0.0049/0.0073

2,3-dichlorobiphenyl (5) --- 0.14 0.11 NA NA NA

2,4’-dichlorobiphenyl (8) --- NA NA 0.024/0.18 0.0037/0.088 0.0045/0.023

2,2’,5-trichlorobiphenyl (18) --- NA NA 0.024/0.086 0.028/0.14 0.0038/0.013

2,4,4’-trichlorobiphenyl (28) --- NA NA 0.036/0.069 0.0073/0.036 0.0056/0.014

2,4,5-trichlorobiphenyl (29) --- 0.075 0.071 NA NA NA

2,2’,3,5’-tetrachlorobiphenyl (44) --- NA NA 0.029/0.23 0.0079/0.041 0.0063/0.025

2,2’,4,4’-tetrachlorobiphenyl (47) --- 0.044 0.088 NA NA NA

2,2’,5,5’-tetrachlorobiphenyl (52) --- NA NA 0.043/0.092 0.0055/0.078 0.0027/0.0078

2,3’,4’,5-tetrachlorobiphenyl (70) --- NA NA 0.043/0.30 0.0044/0.046 0.013/0.036
Page 5 of 10

Contaminant

Regulatory Limit

40 CFR 141.24 

(h)(18)c

MDLs published in Method 

525.2a

MDLs/LCMRLs published in Method 525.3a,b

Full Scan Operating Mode SIM Mode

C18 Cartridge C18 Disk Oasis HLB 

Cartridge

StyreneDivinyl 

Benzene Disk

Oasis HLB 

Cartridge

2,2’,3’,4,6-pentachlorobiphenyl (98) --- 0.15 0.044 NA NA NA

2,3,3’,4’,6-pentachlorobiphenyl (110) --- NA NA 0.026/0.36 0.0030/0.084 0.0030/0.0092

2,3’,4,4’,5-pentachlorobiphenyl (118) --- NA NA 0.046/0.36 0.0050/0.095 0.0077/0.013

2,2’,3,4,4’,5’-hexachlorobiphenyl (138) --- NA NA 0.19/0.41 0.0071/0.058 0.0081/0.016

2,2’,3,4’,5’,6-hexachlorobiphenyl (149) --- NA NA 0.020/0.37 0.0039/0.056 0.0063/0.012

2,2’,4,4’,5,5’-hexachlorobiphenyl (153) --- NA NA 0.029/0.38 0.0033/0.092 0.0092/0.013

2,2’,4,4’,5,6’-hexachlorobiphenyl (154) --- 0.11 0.13 NA NA NA

2,2’,3,3’,4,4’,6-heptachlorobiphenyl (171) --- 0.11 0.14 NA NA NA

2,2’,3,4,4’,5,5’-heptachlorobiphenyl (180) --- NA NA 0.058/0.31 0.0066/0.036 0.0029/0.015

2,2’,3,3’,4,5’,6,6’-octachlorobiphenyl (201) --- 0.13 0.064 NA NA NA

Notes:

a. MDLs calculated according to the procedure published at 40 CFR 136 Appendix B. Method sources: Method 525.2 Tables 3 and 4; Method 

525.3 Tables 15 and 23.

b. Lowest Concentration Minimum Reporting Level (LCMRL) calculated 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.

c. Regulatory detection levels for determining monitoring frequencies published at 40 CFR 141.24(h)(18) for the semivolatile organic 

contaminants. The fourteen PCB congeners listed in Method 525.3 are representative of the major components (by weight percent) of 

Arochlors 1016, 1221, 1232, 1242, 1248, 1254, and 1260. Analyzing for the specific congeners as described in Method 525.3 allows 

screening for Arochlor contamination without requiring complex pattern recognition. Method 525.3 is used for screening only, not 

qualitative or quantitative analysis of PCBs. If any of the fourteen PCB congeners is identified in a sample analyzed using Method 525.3, 

quantitation for total PCBs (as decachlorobiphenyl) is performed by analyzing a sample duplicate using EPA Method 508A.

d. ND = Not Determined. Detection limits were not determined if a high background concentration or an interference was present that 

prevented accurate quantitation.

e. NA = Not Analyzed.
Page 6 of 10

Table 2. Precision and Accuracy Comparison in Reagent Water between Approved Method 525.2 and Method 525.3. All results are 

expressed as % recovery + % relative standard deviation.

Contaminant

Approved Method 525.2a Method 525.3 (Full Scan Operating Mode)

C18 

Cartridges

C18 Disks Oasis HLB 

Cartridgesb

Baker H2O 

Phobic DVB 

Cartridgesb

Baker H2O 

Phobic DVB 

Speedisksb

Empore 

SDB-XC 

Disksc

UCT 525 

Universal 

Cartridgesb

Horizon 

Atlantic 

DVB Disksb

Alachlor 93 + 12 100 + 5.8 106 + 3.6 96.0 + 5.0 107 + 5.0 98.8 + 6.4 100 + 7.3 95.6 + 8.0

Atrazine 109 + 4.8 119 + 3.7 103 + 1.3 100 + 6.7 96.8 + 6.7 105 + 3.9 111 + 3.5 94.5 + 7.4

Benzo[a]pyrene 116 + 1.9 116 + 6.1 95.4 + 5.5 89.9 + 11 94.5 + 11 96.3 + 7.8 109 + 5.5 88.9 + 3.5

cis-Chlordane (alpha) 72 + 11 74 + 5.5 99.1 + 2.9 97.2 + 5.2 106 + 5.2 96.3 + 5.0 98.0 + 5.3 92.1 + 6.5

trans-Chlordane (gamma) 80 + 8.8 80 + 4.2 91.7 + 1.4 93.7 + 5.3 101 + 5.3 96.3 + 5.0 103 + 1.9 91.2 + 5.0

Chlordane (trans-nonachlor) 87 + 17 90 + 7.8 91.4 + 11 84.5 + 3.7 90.1 + 3.7 93.8 + 6.7 119 + 3.2 86.7 + 4.2

Di(2-ethylhexyl) adipate 84 + 7.1 NDd 106 + 5.2 96.2 + 7.8 96.1 + 7.8 129 + 4.9 112 + 4.1 84.1 + 8.6

Di(2-ethylhexyl) phthalate ND ND 112 + 4.6 106 + 9.1 104 + 9.3 98.9 + 2.7 97.6 + 1.3 77.0 + 2.7

Endrin 108 + 18 116 + 18 94.7 + 14 86.8 + 8.6 110 + 8.6 111 + 5.7 89.0 + 5.7 88.1 + 2.1

Lindane (HCH-γ) 126 + 8 124 + 6.6 96.7 + 3.6 98.1 + 5.6 95.1 + 5.6 93.8 + 6.7 90.0 + 4.4 89.4 + 4.0

Heptachlor 83 + 12 80 + 12 83.5 + 5.0 85.6 + 4.6 87.3 + 4.6 86.3 + 5.6 96.0 + 3.4 91.9 + 9.9

Heptachlor epoxide 70 + 5.5 71 + 8.7 106 + 6.5 97.5 + 3.2 98.9 + 3.2 98.8 + 2.5 104 + 3.1 86.8 + 3.3

Hexachlorobenzene 78 + 11 95 + 8.3 59.5 + 15 68.1 + 5.9 79.4 + 5.9 82.5 + 7.8 94.0 + 5.5 86.8 + 6.1

Hexachlorocyclopentadiene 

(HCCPD) 86 + 5.6 84 + 12 61.7 + 12 58.3 + 13 67.5 + 13 75.0 + 5.4 92.0 + 3.5 72.6 + 6.9

Methoxychlor 123 + 4.2 117 + 1.9 100 + 6.9 96.8 + 6.5 97.4 + 6.5 118 + 4.3 122 + 1.9 94.1 + 4.0

Pentachlorophenol ND 95 + 16 92.9 + 5.6 85.8 + 6.0 93.5 + 6.0 95.0 + 5.4 104 + 4.1 93.0 + 4.4

Simazine 109 + 9.1 120 + 10 96.0 + 1.2 88.0 + 9.3 89.5 + 9.3 108 + 2.7 110 + 3.6 93.9 + 3.8

Toxaphene NAe NA NA NA NA NA NA NA

PCB congeners (IUPAC No.):

2-chlorobiphenyl (1) 80.0 + 7.2 84 + 1.9 83.4 + 3.2 84.7 + 4.6 90.2 + 4.6 85.0 + 4.8 75.0 + 2.7 85.3 + 5.2

4-chlorobiphenyl (3) NA NA 82.4 + 3.0 81.8 + 6.5 87.9 + 6.5 90.0 + 4.5 85.0 + 2.4 88.2 + 4.0

2,3-dichlorobiphenyl (5) 80 + 11 93 + 8.1 NA NA NA NA NA NA

2,4’-dichlorobiphenyl (8) NA NA 78.5 + 3.5 85.4 + 5.6 85.3 + 5.6 88.8 + 7.1 85.0 + 2.4 87.1 + 5.8

2,2’,5-trichlorobiphenyl (18) NA NA 83.4 + 11 80.4 + 2.3 90.7 + 2.3 82.5 + 6.1 104 + 3.1 89.4 + 2.5

2,4,4’-trichlorobiphenyl (28) NA NA 83.2 + 6.0 85.0 + 7.6 93.2 + 7.6 91.3 + 6.9 81.0 + 2.5 84.4 + 6.8

2,4,5-trichlorobiphenyl (29) 75 + 6.7 89 + 5.3 NA NA NA NA NA NA

2,2’,3,5’-tetrachlorobiphenyl 

(44) NA NA 91.2 + 5.3 88.7 + 4.2 97.5 + 4.2 91.3 + 6.9 85.0 + 9.7 87.2 + 7.5
Page 7 of 10

Contaminant

Approved Method 525.2a Method 525.3 (Full Scan Operating Mode)

C18 

Cartridges

C18 Disks Oasis HLB 

Cartridgesb

Baker H2O 

Phobic DVB 

Cartridgesb

Baker H2O 

Phobic DVB 

Speedisksb

Empore 

SDB-XC 

Disksc

UCT 525 

Universal 

Cartridgesb

Horizon 

Atlantic 

DVB Disksb

2,2’,4,4’-tetrachlorobiphenyl 

(47) 71 + 4.1 79 + 7.4 NA NA NA NA NA NA

2,2’,5,5’-tetrachlorobiphenyl 

(52) NA NA 84.3 + 4.4 84.5 + 3.6 89.0 + 3.6 95.0 + 4.3 84.0 + 3.9 89.4 + 5.4

2,3’,4’,5-tetrachlorobiphenyl 

(70) NA NA 89.9 + 7.3 89.2 + 3.5 102 + 3.5 91.3 + 6.9 84.0 + 3.9 87.8 + 8.3

2,2’,3’,4,6-

pentachlorobiphenyl (98) 61 + 16 70 + 4.2 NA NA NA NA NA NA

2,3,3’,4’,6-

pentachlorobiphenyl (110) NA NA 98.2 + 6.7 93.6 + 3.0 98.0 + 3.0 93.8 + 6.7 81.0 + 2.5 87.1 + 3.2

2,3’,4,4’,5-

pentachlorobiphenyl (118) NA NA 92.5 + 5.1 92.8 + 4.1 96.0 + 4.1 97.5 + 6.6 90.0 + 2.6 85.5 + 3.4

2,2’,3,4,4’,5’-

hexachlorobiphenyl (138) NA NA 94.5 + 4.0 94.0 + 0.77 93.7 + 0.8 90.0 + 4.5 86.0 + 4.7 85.9 + 5.7

2,2’,3,4’,5’,6-

hexachlorobiphenyl (149) NA NA 96.1 + 5.8 94.6 + 4.2 96.4 + 4.2 93.8 + 5.1 87.0 + 5.8 84.3 + 6.6

2,2’,4,4’,5,5’-

hexachlorobiphenyl (153) NA NA 92.2 + 0.9 97.5 + 2.5 98.3 + 2.5 95.0 + 4.3 79.0 + 2.5 83.1 + 4.4

2,2’,4,4’,5,6’-

hexachlorobiphenyl (154) 73 + 9.6 83 + 11 NA NA NA NA NA NA

2,2’,3,3’,4,4’,6-

heptachlorobiphenyl (171) 71 + 10 71 + 13 NA NA NA NA NA NA

2,2’,3,4,4’,5,5’-

heptachlorobiphenyl (180) NA NA 88.5 + 4.1 93.6 + 9.9 87.2 + 9.9 88.8 + 5.4 101 + 2.0 81.9 + 6.0

2,2’,3,3’,4,5’,6,6’-

octachlorobiphenyl (201) 101 + 8.7 102 + 4.2 NA NA NA NA NA NA

Notes:

a. All samples fortified at 0.5 μg/L, except pentachlorophenol which was fortified at 2.0 μg/L. Sources: Method 525.2 Tables 3 and 4.

b. All samples fortified at 0.25 μg/L with two exceptions: di(2-ethylhexyl) phthalate was fortified at 2.0 μg/L (samples fortified with di(2-

ethylhexyl) phthalate at 0.25 μg/L exhibited high background) and pentachlorophenol was fortified at 1.0 μg/L. Sources: Method 525.3 

Tables 3, 5, 7, 9, 11, and 13. Note: Toxaphene data collected in SIM mode (See Table 3 below).
Page 8 of 10

c. All samples fortified at 0.20 μg/L with two exceptions: di(2-ethylhexyl) phthalate was fortified at 2.0 μg/L and pentachlorophenol was 

fortified at 0.8 μg/L. Sources: Method 525.3 Tables 3, 5, 7, 9, 11, and 13. 

d. ND = Not Determined

e. NA = Not Analyzed
Page 9 of 10

Table 3. Method 525.3 Precision and Accuracy in Fortified Reagent Water using SIM GC/MS Analysisa. Except as noted, fortification level is 

0.025 μg/L. All results are expressed as %recovery + %relative standard deviation.

Contaminant Oasis HLB Cartridges Baker H2O Phobic 

DVB Speedisks

Baker H2O Phobic 

DVB Cartridges

(toxaphene only)

Empore SDB-XC 

Disks (toxaphene

only)

Alachlor 114 + 2.7 111 + 2.3

Atrazine 117 + 5.7 106 + 5.0

Benzo[a]pyrene 81.0 + 4.8 89.6 + 2.4

cis-Chlordane (alpha) 110 + 4.1 100 + 1.3

trans-Chlordane (gamma) 89.9 + 1.4 100 + 0.6

Chlordane (trans-nonachlor) 98.9 + 2.8 99.5 + 1.0

Di(2-ethylhexyl) adipateb 114 + 4.2 94.9 + 5.1

Di(2-ethylhexyl) phthalatec 118 + 7.8 NDf

Endrin 97.5 + 6.1 105 + 3.6

Lindane (HCH-γ) 104 + 6.9 102 + 1.8

Heptachlor 104 + 9.3 96.7 + 3.2

Heptachlor epoxide 108 + 3.8 103 + 2.0

Hexachlorobenzene 90.2 + 9.6 94.7 + 2.1

Hexachlorocyclopentadiene (HCCPD) 102 + 7.6 85.8 + 5.1

Methoxychlor 113 + 8.4 104 + 2.9

Pentachlorophenold 79.0 + 7.9 99.5 + 1.4

Simazine 85.2 + 12 105 + 0.7

Toxaphenee 82.9 + 5.0 114 + 1.0 100 + 3.6 107 + 5.3

PCB congeners (IUPAC No.):

2-chlorobiphenyl (1) 99.9 + 2.7 96.4 + 1.6

4-chlorobiphenyl (3) 96.8 + 4.8 97.3 + 1.7

2,4’-dichlorobiphenyl (8) 109 + 12 95.0 + 1.8

2,2’,5-trichlorobiphenyl (18) 101 + 6.1 97.2 + 2.0

2,4,4’-trichlorobiphenyl (28) 90.8 + 10 94.8 + 1.2

2,2’,3,5’-tetrachlorobiphenyl (44) 94.5 + 4.2 98.4 + 2.2

2,2’,5,5’-tetrachlorobiphenyl (52) 97.0 + 4.6 96.5 + 2.2

2,3’,4’,5-tetrachlorobiphenyl (70) 88.3 + 15 97.6 + 1.8

2,3,3’,4’,6-pentachlorobiphenyl (110) 92.0 + 3.7 98.7 + 1.4

2,3’,4,4’,5-pentachlorobiphenyl (118) 86.2 + 8.8 97.0 + 1.5

2,2’,3,4,4’,5’-hexachlorobiphenyl (138) 86.7 + 3.7 101 + 1.1

2,2’,3,4’,5’,6-hexachlorobiphenyl (149) 95.3 + 4.7 96.8 + 1.3
Page 10 of 10

Contaminant Oasis HLB Cartridges Baker H2O Phobic 

DVB Speedisks

Baker H2O Phobic 

DVB Cartridges

(toxaphene only)

Empore SDB-XC 

Disks (toxaphene

only)

2,2’,4,4’,5,5’-hexachlorobiphenyl (153) 86.8 + 2.0 95.9 + 1.0

2,2’,3,4,4’,5,5’-heptachlorobiphenyl (180) 99.7 + 9.5 92.8 + 1.5

a. Method 525.3 source tables: Tables 17, 19 and 21.

b. Di(2-ethylhexyl)adipate fortification level = 0.1 μg/L

c. Di(2-ethylhexyl)phthalate fortification level = 0.25 μg/L

d. Pentachlorophenol fortification level = 0.1 μg/L

e. Toxaphene fortification level = 1.0 μg/L

f. ND = Not Determined. Recovery could not be determined due to low fortification concentration relative to the background level.