Anal. Chem. 1985, 57, 2469-2473
terpretation and computation procedures also were demonstrated with GC/MS data acquired from extracts of triplicate aliquots of two environmentally contaminated sediments from the harbor at New Bedford, MA. These sediments had previously been analyzed in the same laboratory during an interlaboratory study (2). In both sediment extracts, PCB concentrations determined with automated data interpretation were higher than those determined with nonautomated procedures (Table IV). This resulted from the capability of automated procedures to detect more PCB congeners than the analyst. For example, in sediment 11,52 congeners were detected and measured with automated procedures while only 42 were identified and measured by the analyst. Inspection of appropriate spectra verified the validity of the additional identifications with automated procedures. In addition, precision of triplicate measurements was better with automated procedures than with nonautomated procedures (Table IV) . Total PCB concentrations measured with the isomer group approach compared well with concentrations measured previously in the same laboratory when different extracts of the same sediment samples were analyzed to determine PCB content as Aroclor concentrations. The previously measured mean of duplicate determinations of total Aroclor PCB concentration was 1200 pg/kg in sediment I1 and 110 pg/kg in sediment 111. When PCB concentrations were measured as isomer groups, the mean of triplicate measurements in sediment I1 was 1010 pg/kg with nonautomated data interpretation and 1099 pg/kg with automated interpretation and in sediment I11 they were 96.5 pg/kg and 122 pg/kg, respectively. Cost Effectiveness of Automated Procedures. A comparison of resources required for both human and automated interpretation and computation indicates the cost effectiveness
2469
of the automated procedures. For each GC/MS data file, 12-15 h (including 5 to 6 h of computer terminal use) were required for an experienced analyst to obtain PCB concentration data. Automated procedures, however, required about 0.5 h of an analyst’s time and less than 1h of computer time. CONCLUSIONS The automated interpretation and computation procedures described here not only provide a cost-effective approach to PCB determinations but also provide accurate and precise data. As the software is used in other laboratories and for other determinations, additional refinements will improve its speed and efficiency. ACKNOWLEDGMENT The authors gratefully acknowledge the assistance and cooperation of Phillip W. Albro (Laboratory of Environmental Chemistry, National Institute of Environmental Health Sciences, Research Triangle Park, NC), who provided the commercial Aroclor mixtures. LITERATURE CITED (1) Gebhart, J. E.; Hayes T. L.; Alford-Stevens, A. L.; Budde, W. L. Anal. Chem. w 8 s , 57, 2458. (2) Alford-Stevens, A. L.; Budde, W. L.; Bellar, T. A. Anal. Chem. 1985, 5 7 , 2452. (3) Mullin, M. D.; Pochini, C. M.; McCrindle, S.; Romkes, M.; Safe, S. H.; Safe, L. M. Environ. Sci. Technol. 1984, 18, 468. (4) Rosenthal, D.; Bursey, J. T. Paper No. T4 presented at the 20th Annual Conference on Mass Spectrometry and Allied Topics, Dallas, TX, June 1972. (5) Sokolow, S.; Karnofsky, J.; Gustafson, P. “The Finnigan Library Search Program”; Flnnlgan Corporation: San Jose, CA, 1978; Application Report No. 2. (6) Albro, P. W.; Corbett, J. T.; Schroeder, J. L. J . Chromatogr. 1981, 205, 103.
RECEIWDfor review March 20,1985. Accepted June 20,1985.
Surrogate Standards for the Determination of Individual Polychlorinated Biphenyls Using High-Resolution Gas Chromatography with Electron Capture Detection S. D. Cooper, M. A. Moseley, and E. D. Pellizzari* Analytical and Chemical Sciences, Research Triangle Institute, P.O. Box 12194, Research Triangle Park, North Carolina 27709
A method for calibrating an electron capture detector (ECD) for quantitatlve analysis of ail 209 individual polychlorinated biphenyl (PCB) congeners was developed by using a secondary standard containing 31 surrogate PCB congeners. By use of the relative response factors (RRFs) for 203 of the 209 PCBs determlned by high resolution gas chromatography wlth ECD, RRFs were clustered to allow a commercially available PCB surrogate to represent a group of PCB congeners. With this statistically based approach, the callbration bias was < l o % and the range of the percent relative standard devlatlon for the 31 groups of RRFs was 0-4.9%.
The analysis of samples for polychlorinated biphenyls (PCBs) by using high-resolution gas chromatography with 0003-2700/85/0357-2469$0 1.50/0
electron capture detection (HRGC/ECD) has prompted a need for a simpler way to calibrate a gas chromatographic instrument. Since 209 PCB congeners exist, it is a timeconsuming and expensive task to carry out calibrations using the full set of PCB congeners. Alternatively, the use of Aroclors, technical mixtures of PCB congeners, can be risky since some variations may occur, e.g., from lot-to-lot differences. One method we have applied to reduce these problems is to use a set of surrogate or secondary PCB congeners, each of which represents a group of PCB congeners having similar response factors as determined by using an electron capture detector. This technique allows the use of more readily available congeners, from commercial sources, to represent the congeners which may not be available. By utilizing the response factors and retention times we have previously determined (l),we were able to statistically 0 1985 American Chemical Society
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ANALYTICAL CHEMISTRY, VOL. 57, NO. 13, NOVEMBER 1985
Table I. Grouping of PCB Congeners to Establish Surrogate Standards” group no.
isomers
RRFs
1 2 3 4 5 6
*2 *3 *4 *2,2’ *2,3 *3,3’ 2,3’ 3,4’ *4,4’ 2,3,4,5,6,2’,6 2,3,4,6,2’,3’,5’ *3,5 *2,6 2,6,2’ *3,4 2,4,3’ *2,4’ 3,5,4’ 3,4,4’ *2,5 2,4,2’,6’ 2,3,6,2’,4’,5’ *2,4,6,2,6’ *2,3,4,5,6,2’,4’,6’ 2,6,3’ *2,6,2’,6’ 3,4,5,3’,4’ 2,3,2’ 3,4,3’ 2,6,4’ 2,6,3‘,4‘ *2,4 2,5,2’,6’ 2,3,5,2’,4’,5’ 2,3,6,2’,4’,6’ 2,3,4,6,2’,3’,5’,6’ *3,4,2‘ 2,3,4,6,2’,3’ 2,3,5,6,2’,3’,5’ 2,5,4’ 2,4,2’ 2,5,2‘ 2,3,4,5,6,2’,3’,4’ 2,3,6,2’,6’ 2,3,6,2’,5’ 3,4,5,2’ 2,3,6,2’ 2,3,5,2’,4‘ 2,4,5,2’,4’ 2,3,2’,5’ *2,5,3‘ 2,3,5,2’,4’,6’ 2,3,6 *2,4,6,2’,4’,6’ 2,43 2,4,5,2’ 2,3,5,2’,6’ 2,4,5,2’,6’ 3,4,3’,5’ 2,3,3’,5’ 2,3,5,2’,5’ 2,3,4,5,3’,4’,5’ 2,3,4,2‘ 3,4,5,2’,3’ *2,4,4’ 2,4,5,2’,5’ 2,3,6,2‘,4‘ 2,3,5,6,2‘ 3,5,3’ 2,3,5,2’,3’ 2,3,6,2’,3’ 2,3,4,5,2’,3’,5’,6’ 2,3,4,2’,3’,4’ *2,4,6,3‘ 2,6,3‘,5’ 2,4,3’,4’
29.20 47.61 55.97 10.24 12.66 7.691 7.4956 7.4956 6.632 6.572 6.301 5.605 5.202 4.890 4.854 4.734 4.548 4.270 3.880 3.869 3.755 3.712 3.704 3.168 3.067 2.880 2.808 2.678 2.648 2.633 2.605 2.593 2.573 2.521 2.469 2.464 2.460 2.427 2.418 2.413 2.405 2.402 2.387 2.377 2.377 2.362 2.319 2.305 2.305 2.305 2.297 2.258 2.198 2.158 2.137 2.122 2.054b 2.054’ 2.0206 2.020‘ 1.994 1.993 1.959 1.869 1.852 1.847 1.824 1.820 1.808 1.802b 1.802b 1.759 1.789 1.780 1.775 1.765
7 8 9 10 11 12 13 14 15 16
17
18
19
20
21
22
max % bias a a
group no. 22
a a
a a
5.0
RRFs
2,3,6,2’,3‘,6‘ 2,3,4,5,2’,3’,5’ 2,4,2’,5’ 2,3,4,6,2‘,6‘ 2,3,5,6,3‘,5‘ *2,3,2’,3’ 2,3,4,2’,3’,6’ 2,3,4,2’,3’,5’ 2.3.2’.4’ 2,4,3’,5’ 2,4,5,2’,3’ 2,3,5,6,2’,6’ 3,4,3’,4’ *2,4,5,2’,4’,6’ 3,4,5,3’,4’,5’ 2,3,5,3’ 2,3,6,3’ 2,4,5,3‘ 2,3,5,6,2’,4’,6’ 2,3,5,2’,3’,6’ 2,3,6,2’,4’,5’ 2,3,5,6,2’,3’,5’,6’ 2,4,6,2’,5’ 2,4,6,2’,3’ 2,3,5,6,2’,3’,6’ 2,3,3’ 2,3,5,3‘,5‘ 2,4,5,3’,5’ 2,3,4,3’ 3,4,5,3’ 2,3,5,6,3’,4’ 2,3,4,5,2’,3’,6’ 2,3,4,4’ 2,3,4,6,2’,5’ 3,4,5 *2,5,2’,5’ 2,4,5,3’,4’ 2,4,6,2‘,4‘ 2,3,4,5,3’,5’ 2,3,4,3‘,4‘ 2,4,2’,4’ 2,4,6,4’ 2,3,4,6,2’ 2,3,4,2’,4’,6’ 2,3,5,6,2’,3’ 2,4,6,3’,5‘ 2,4,5,4’ 2,3,6,4‘ 2,3,5,4’ 2,3,3’,4’ 2,5,3’,4’ 2,3,4,5,2’,3’,4’,6’ 2,3,4,6,2‘,4‘ 2,3,5,6,2’,4’ 2,3,6,3‘,4‘,5‘ 2,3,4,5,2’,6’ 2,3,4,2‘,4‘ 2,3,4,3’,5’ 3,4,5,3’,5’ *2,3,4,6,4’ 2,3,4,6,2’,4’,5’ 2,3,4,5,2’,3’ 3,5,2’ 3,4,5,2‘,4‘ 2,3,4,2’,4’,5’ 2,3,4,3‘,4‘,5‘ 2,4,6,3‘,4’ 2,3,5,6,3’ 2,3,4,6,2’,3’,4’,6’ 2,3,4,6 2,3,4,2’,3’ 2,4,6,3‘,4‘,5‘ 2,3,6,3’,5’ 2,3,4 2,3,4,5,2’ 2,3,4,5,2’,4’,6’
1.759 1.722 1.713 1.710 1.677 1.671 1.659 1.637 1.636 1.635 1.614 1.610 1.595 1.595 1.586 1.585b 1.585’ 1.585b 1.565 1.564b 1.564b 1.529 1.508 1.502 1.499 1.494 1.490‘ 1.490’ 1.481b 1.481b 1.472 1.471 1.464 1.456 1.446 1.444 1.442 1.437 1.434 1.429 1.426 1.425 1.416 1.409 1.406 1.392 1.3886 1.388b 1.388b 1.387 1.377 1.374 1.374 1.370 1.369 1.363 1.325 1.321b 1.321b 1.321 1.318 1.316 1.315 1.307 1.306 1.294 1.276 1.273 1.264 1.246 1.242’ 1.228 1.221 1.218 1.213 1.211
I
23
a a 2.5
6.1 -0.3 -1.4 24 3.2 2.5 -3.3
4.0
-5.5
isomers
25
1.9
-8.4
1.6 26
,
I
max % bias 3.1
4.1
-4.4
-5.0
-4.9
ANALYTICAL CHEMISTRY, VOL. 57, NO. 13, NOVEMBER 1985
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Table I (Continued) group no.
isomers
RRFs
26
2,3,5,6,4‘ 2,4,5,3’,4’,5’ 2,3,5,3’,4’,5’ 2,3S *2,3,4,6,2‘,3‘,4‘ 2,3,4,5,3’ 2,3,4,5,2’,3’,4’,5’ 2,3,4,6,2’,4’,6’ 2,3,4,2’,5’ 3,4,5,2’,5‘ 2,5,3’,5’ 2,3,4,5,2’,4’ 2,3,4,5,6,2’,4’ 2,3,4,5,3’,4’ 2,3,5,6 2,3,4,5,6,2’,3’,5’ 2,3,4,5,6,2‘ 2,3,4,5,2’,4’,5’ 2,3,4,5,6,2’,3’,6’ *3,4,5,4’ 2,3,4,5,6,4’ 2,3,4,6,3’,5’ 2,3,4,5 2,4,5,2’,4’,5’ 2,3,4,6,3‘,4’ 2,3,4,5,6,2’,3’,5’,6’
1.202 1.195* 1.195b 1.192b 1.188 1.184 1.178 1.173 1.163 1.147 1.154 1.154 1.142 1.140 1.125 1.119 1.116 1.098 1.098 1.092 1.087 1.073 1.062 1.060 1.038 1.032
27
28
max % bias
group no. 28
29
30
-3.0
31
-3.2
isomers 2,3,4,5,6,3’,4’,5’ *2,3,5,6,2’,5’ 2,3,4,5,6,2’,3’,4’,5’ 2,3,4,6,3’ 2,3,4,5,2’,3’,4’ 2,3,4,5,6,3’ 2,3,4,5,6,3‘,4‘ *2,3,4,5,6,2’,5’ 2,3,4,5,6,2’,3’,4’,6’ 2,3,4,5,6,2’,3’ 2,3,4,5,6,2’,4’,5’ 2,3,4,5,4‘ 2,4,6 2,3,4,2‘,6’ 2,3,5,6,2‘,4‘,5’ 2,3,4,5,6,3’,5’ 2,3,4’ *2,3,4,5,6,2’,3’,4’,5’,6’ 2,3,5,6,2’,3’,4’ 2,3,5,6,3’,4’,5’ 2,3,4,5,6 *2,3,4,5,2’,5’ 2,3,4,6,3’,4’,5’ 2,3,5,2’
RRFs 1.013 1.005 1.002 0.990 0.946 0.943 0.942 0.938 0.930 0.919 0.910 0.883 0.876 0.830b 0.830b 0.793 0.770 0.746 0.720 0.702 0.621 0.604 0.578 0.566 0.331
max % bias
6.6
-10.1
42.5 -7.7c
Surrogate for the group. Not applicable. RRF is average of RRFs for two or three isomers. Excluding isomer. determine the congeners best suited to act as surrogates. This paper describes the method used to do so and the advantages and disadvantages it has.
EXPERIMENTAL SECTION Reagents. The Aroclors used in this study, Aroclor 1016, Aroclor 1254, and Aroclor 1260, were obtained from the U S . Environmental Protection Agency’s Pesticides and Industrial Chemical Repository,Research Triangle Park, NC. The individual PCB congeners used were obtained as solutions from the US. EPA station in Grosse Ile, MI. The neat congeners were obtained from Foxoboro/Analabs, North Haven, CT. The isooctane used was nonspectro, “distilled-in-glass”grade obtained from Burdick and Jackson Laboratories, Inc., Muskegon, MI. Apparatus. The fused-silica capillary column was 60 m X 0.24 mm i.d., had a DB-5 phase (approximately equivalent to bonded SE-54) of 0.1 pm thickness, and was obtained from J&W Scientific, Rancho Cordova, CA. The gas chromatograph used was a Hewlett-Packard 5880A, level 4, set up for capillary column use and equipped with an electron capture detector. Injections were made with a Hewlett-Packard Model 7672A autoinjector. The helium carrier gas was purified by using a 13X molecular sieve/activated-charcoal trap along with an oxygen scrubber. The make-up gas for the ECD was similarly purified and was composed of 10% hydrogen in nitrogen, by volume. Instrument Calibration. Instrument calibration was carried out as was previously done ( I ) . Only the calibration procedures pertaining to the DB-5 column were used. RESULTS AND DISCUSSION The determination of the primary relative response factors (RRFs) allowed the grouping and subsequent designation of surrogate PCB congeners. The RRFs relative to the octachloronaphthalene internal standard were chosen, and the RRFs of all of the PCB congeners were ordered from high to low values. All congeners available commercially were noted as potential surrogate congeners. Groups were then chosen so that a t least one of the potential surrogate congeners was included and so that the maximum difference or bias between the RRF of the surrogate congeners representing the group and the RRF of the mean of the congeners was less than 5%. Since the responses for the lower chlorinated congeners were
more variable and generally lower (1-3), many of these isomers could not be clustered with other congeners. The resultant groupings are shown in Table I. The percent difference shown in Table I is the difference between the mean RRF of the group and the RRF of the surrogate. This value was kept under the ceiling of 5% except in the last group. However, by excluding the congener 2,3,5,2‘, which appears to be anomalous, the resultant bias is within the ceiling. The maximum percent bias shown reflects the difference between the RRF of the surrogate congener and the most deviant congener of the group. Only 5 of the 31 groups exceeded *6% in this regard. A reasonable correlation between the RRF of the surrogate congener and the RRFs of the individual congeners in the corresponding group was established. The Aroclor peaks in a cocktail mixture were quantitated two ways: first, by using the RRFs directly generated for the corresponding individual PCB congeners (primary standard); second, by using the corresponding surrogate congeners. A standard was prepared in isooctane that included 250 pg/pL Aroclor 1016,200 pg/pL Aroclor 1254, and 100 pg/pL Aroclor 1260; 60 pg/pL 4-bromobiphenyl (MBB), 40 pg/pL 2,2’,5tribromobiphenyl, and 20 pg/pL octachloronaphthalene were used as the three internal standards. When the cocktail standard was analyzed by HRGC/ECD the 109 peaks corresponding to the PCB congeners present were each identified as to which congener(s) it represented. The primary RRFs of the congeners of each peak were averaged. The RRFs used were those relative to the internal standard which elutes closest to the Aroclor peak in question. Thus, for example, the third Aroclor peak is quantified by using RRFs relative to the first eluting internal standard, MBB. The surrogate congener RRFs were used similarly in quantitation. The only difference was that a surrogate congener’s RRF replaced the RRF of each primary congener standard it represented in any of the Aroclor peaks. The surrogate, or secondary, RRFs were then averaged to obtain an average secondary RRF of the Aroclor peak. For example, the surrogate congeners of groups 4 and 9 were used to represent the PCB congeners 2,2‘ and 2,6 found in Aroclor peak 003 (Table 11). The two RRFs were averaged to arrive
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ANALYTICAL CHEMISTRY, VOL. 57, NO. 13, NOVEMBER 1985
Table 11. Comparison of Quantitation Using Primary vs. Secondary RRFs
Aroclor peak no.
prim std
001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057
10.79 14.30 8.78 3.30 60.00 8.52 51.41 5.55 22.88 23.38 3.85 20.90 0.51 0.88 5.26 3.34 0.75 47.93 17.83 3.84 2.17. 3.90 4.84 1.85 14.81 0.90 10.34 5.05 0.80 17.43 6.22 9.83 7.83 8.74 3.48 0.69 40.00 0.79 4.32 11.64 0.70 4.21 26.27 3.59 2.16 5.44 5.60 25.95 7.54 0.85 1.52 0.40 6.11 0.66 9.88 4.53 4.55
Aroclor peak sec std % diff no. 10.79 14.30 8.78 3.30 60.00 10.91 51.41 5.59 22.55 23.60 4.17 20.12 0.54 0.92 5.26 3.24 0.74 49.02 18.01 3.84 2.42 3.97 4.99 1.92 14.58 0.90 10.52 5.26 0.95 23.13 6.11 9.97 8.15 7.29 3.48 0.64 40.00 0.66 3.60 12.52 0.67 3.54 30.76 3.55 1.97 4.71 5.27 27.49 8.75 0.87 1.44 0.29 5.44 0.61 9.90 4.55 3.52
0.00 0.00 0.00 0.00 0.00 28.14 0.00 0.81 -1.44 0.90 8.23 -3.73 4.89 3.98 0.00 -3.14 -1.73 2.29 1.00 0.00 11.22 1.82 3.14 3.79 -1.57 0.22 1.73 4.16 18.43 32.64 -1.64 1.46 4.03 -16.64 0.00 -7.29 0.00 -16.65 -16.63 7.61 -3.59 -16.07 17.09 -1.20 -8.54 -13.34 -5.93 5.93 16.09 1.76 -5.27 -27.61 -10.92 -7.87 0.23 0.44 -22.53
058 059 060 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090 091 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 .
prim std 26.28 2.95 4.91 5.14 0.44 0.56 1.23 16.42 16.91 1.89 0.32 0.73 5.72 0.53 16.39 10.42 6.97 0.47 9.65 1.06 1.17 2.13 24.98 4.70 2.16 2.69 3.01 0.65 7.50 4.41 6.24 1.08 0.87 7.49 2.30 3.17 2.56 0.23 1.68 1.33 0.16 13.77 0.60 0.20 0.56 18.96 0.29 5.58 3.36 0.34 3.39 3.58 0.20 20.00 0.90 743.81
sec std % diff 20.34 2.72 4.91 4.92 0.47 0.47 1.08 14.84 17.70 2.06 0.36 0.69 6.31 0.56 15.89 10.16 7.28 0.51 10.62 1.18 1.20 2.05 24.52 4.85 1.40 2.85 2.86 0.67 7.57 4.42 6.21 1.08 0.97 7.55 2.36 3.11 2.66 0.24 1.69 1.28 0.17 13.69 0.56 0.20 0.56 19.06 0.28 5.53 3.46 0.35 3.50 3.60 0.20 20.00 0.90 749.13
-22.60 -7.57 0.00 -4.28 5.63 -16.84 -12.42 -9.67 4.66 9.05 14.47 -4.95 10.39 5.85 -3.01 -2.49 4.36 7.45 10.08 10.54 1.79 -3.85 -1.83 3.30 -35.12 5.76 -4.72 3.24 0.92 0.23 -0.51 -0.55 11.45 0.80 2.61 -1.61 4.15 2.16 0.59 -4.05 4.35 -0.57 -7.00 2.04 -0.53 0.56 -2.42 -0.86 3.04 2.94 3.09 0.78 -0.15 0.00 0.33 0.72
a t a secondary RRF for the Aroclor peak. I n this case there is n o difference between t h e primary and secondary RRFs, since each of t h e two groups is the individual PCB congener alone. By quantitating t h e same raw d a t a using t h e two methods, a comparison was made between t h e determined levels of PCBs as shown in Table 11. As indicated in Table I1 most of t h e Aroclor peaks can be estimated reasonably well by using t h e surrogate PCB congeners. the two determinations were within &5%for over 60% of the peaks. However, approximately one-fifth of the peaks had differences exceeding & l o % . T h e differences in these cases were ascribed t o the occasional change in response ratios
of one internal standard (OCN) relative t o another (MBB or TBB). T h i s variation caused some congeners to have RRFs relative t o MBB or TBB; thus these congeners could be grouped exactly the same as those RRFs relative to OCN. In some cases this error was quite significant. Another source of error was due to the estimation process itself. T h e two sources of error also occurred in combination t o produce the greatest discrepancies. In spite of the differences, total PCBs determined in both cases were within 1%of each other, which is quite acceptable for most analyses. While this agreement is good, it should be pointed out that the total PCBs determined (-743 ng) was substantially different from t h e gravimetrically determined total of 550 ng. While this discrepancy is not fully understood, i t is known that in some cases some PCB congener solutions obtained had significant levels of impurities that were transparent to ECD but included in the gravimetric determination.
CONCLUSIONS These results demonstrate the utility of surrogate PCB congeners in the determination of PCB levels in an extract. By use of t h e surrogate PCB congeners, the total level determined correlates very well with the total level determined by a straightforward approach using the primary RRFs. Therefore, for determinations where the total PCB level is of primary importance, this method allows a laboratory to carry o u t the analyses using a minimum of PCB congener standards. Since a limited supply of all 209 congeners is available, this method, using commercially available congeners, eliminates t h e difficulty and expense of obtaining all congeners. For determinations requiring more specific congener information, this method provides good estimates. This method is also more easily suited to frequent instrumental calibrations using PCB congeners instead of Aroclor mixtures, since there is a manageable number of congeners involved. One aspect not addressed in this paper is the interlaboratory variations that may exist in grouping the PCB congeners with respect to their response factors. This problem may or may not be significant depending on a variety of parameters. While not conclusive, a comparison of t h e RRFs generated by our lab (2) to those generated by Mullin et al. (2) shows reasonably good correspoadence in most cases, even though different instruments were used. The use of surrogate standards makes the analysis of PCBs by HRGC/ECD or by HRGC/MS more accessible t o all laboratories.
ACKNOWLEDGMENT We thank L. Williams of U S . EPA, Las Vegas, for his helpful suggestions and M. Mullin of t h e U.S. EPA, Grosse Ile, MI, for the solutions of primary PCB congener standards. Registry No. 2-Chlorobiphenyl, 2051-60-7; 3-chlorobiphenyl, 2051-61-8; 4-chlorobiphenyl, 2051-62-9; 2,2’-dichlorobiphenyl, 13029-08-8;2,3’-dichlorobiphenyl,25569-80-6; 2,3-dichlorobiphenyl, 16605-91-7;2,4-dichlorobiphenyl,33284-50-3; 2,4’-dichlorobiphenyl, 34883-43-7;2,5-dichlorobiphenyl,34883-39-1; 2,6-dichlorobiphenyl, 33146-45-1; 3,3/-dichlorobiphenyl,2050-67-1; 3,4-dichlorobiphenyl, 2974-92-7; 3,4’-dichlorobiphenyI, 2974-90-5; 3,5-dichlorobiphenyl, 34883-41-5; 4,4’-dichlorobiphenyl, 2050-68-2; 2,6,2’-trichlorobiphenyl, 38444-73-4; 2,4,3’-trichlorobiphenyl,55712-37-3; 3,5,4’trichlorobiphenyl, 38444-88-1; 3,4,4’-trichlorobiphenyl, 38444-90-5; 2,6,3’-trichlorobiphenyl, 38444-76-7; 2,3,2‘-trichlorobiphenyl, 38444-78-9; 3,4,3’-trichlorobiphenyl,55712-37-3; 2,6,4’-trichlorobiphenyl, 38444-77-8; 3,4,2’-trichlorobiphenyl,38444-86-9; 2,5,4’-trichlorobiphenyl,16606-02-3; 2,4,2’-trichlorobiphenyl, 37680-66-3; 2,5,2’-trichlorobiphenyl,37680-65-2; 2,5,3‘-trichlorobiphenyl, 38444-81-4; 2,3,6-trichlorobiphenyl,55702-45-9; 2,4,5trichlorobiphenyl, 15862-07-4;2,4,4’-trichlorobiphenyl, 7012-37-5; 3,5,3’-trichlorobiphenyl,38444-87-0; 2,3,3’-trichlorobiphenyl, 38444-84-7; 3,4,5-trichlorobiphenyl,53555-66-1;3,5,2’-trichlorobiphenyl, 76708-77-5; 2,3,4-trichlorobiphenyl,55702-46-0; 2,3,5trichlorobiphenyl, 55720-44-0;2,4,6-trichlorobiphenyl,35693-92-6;
ANALYTICAL CHEMISTRY, VOL. 57, NO. 13, NOVEMBER 1985
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2,3,5,2’,3‘,6’-hexachlorobiphenyl, 52744-13-5; 2,3,5,6,3’,4’-hexa2,3,4‘-trichlorobiphenyl, 38444-85-8; 2,4,2’,6’-tetrachlorobiphenyl, 2,3,4,6,2‘,5’-hexachlorobiphenyl, 68194-04-7; 2,6,2’,6’-tetrachlorobiphenyl,15968-05-5; 2,5,2’,6’- chlorobiphenyl, 74472-44-9; tetrachlorobiphenyl, 41464-41-9; 3,4,5,2’-tetrachlorobiphenyl, 68194-14-9;2,3,4,5,3’,5’-hexachlorobiphenyl,39635-35-3; 59291-64-4; 2,3,5,6,2’,3’-hexa70362-48-0; 2,3,6,2’-tetrachlorobiphenyl,70362-45-7; 2,3,2’,5’- 2,3,4,2’,4’,6’-hexachlorobiphenyl, chlorobiphenyl, 52704-70-8; 2,3,4,6,2’,4‘-hexachlorobiphenyl, tetrachlorobiphenyl,41464-39-5; 2,4,5,2’-tetrachlorobiphenyl, 70362-47-9; 3,4,3‘,5‘-tetrachlorobiphenyl,41464-48-6; 2,3,3’,5’- 56030-56-9;2,3,5,6,2’,4’-hexachlorobiphenyl,68194-13-8; 2,3,6,3’,4’,5’-hexachlorobiphenyl, 74472-45-0; 2,3,4,5,2’,6’-hexatetrachlorobiphenyl, 41464-49-7; 2,3,4,2’-tetrachlorobiphenyl, 2,3,4,5,2’,3’-hexachlorobiphenyl, 52663-59-9; 2,4,6,3’-tetrachlorobiphenyl,60233-24-1; 2,6,3’,5’- chlorobiphenyl, 68194-15-0; 55215-18-4;2,3,4,2’,4’,5’-hexachlorobiphenyl,35065-28-2; tetrachlorobiphenyl,74338-23-1; 2,4,3’,4’-tetrachlorobiphenyl, 69782-90-7; 2,4,6,3’,4’,5’-hexa32598-10-0; 2,4,2’,5’-tetrachlorobiphenyl,41464-40-8; 2,3,2’,3’- 2,3,4,3’,4’,5’-hexachlorobiphenyl, tetrachlorobiphenyl,38444-93-8;2,3,2‘,4’-tetrachlorobiphenyl, chlorobiphenyl,59291-65-5; 2,4,5,3‘,4’,5‘-hexachlorobiphenyl, 36559-22-5; 2,4,3’,5’-tetrachlorobiphenyl,73575-52-7; 3,4,3’,4’- 52663-72-6;2,3,5,3’,4’,5’-hexachlorobiphenyl,39635-34-2; 2,3,4,5,2’,4’-hexachlorobiphenyl, 35694-06-5; 2,3,4,5,3‘,4‘-hexatetrachlorobiphenyl,32598-13-3; 2,3,5,3’-tetrachlorobiphenyl, 70424-67-8;2,3,6,3’-tetrachlorobiphenyl,74472-33-6; 2,4,5,3’- chlorobiphenyl, 38380-08-4;2,3,4,5,6,2’-hexachlorobiphenyl, 41411-61-4;2,3,4,5,6,4’-hexachlorobiphenyl,41411-63-6; tetrachlorobiphenyl,73575-53-8; 2,3,4,3’-tetrachlorobiphenyl, 74338-24-2; 3,4,5,3’-tetrachlorobiphenyl,70362-49-1; 2,3,4,4‘- 2,3,4,6,3’,5’-hexachlorobiphenyl, 74472-43-8; 2,4,5,2’,4’,5’-hexatetrachlorobiphenyl,33025-41-1; 2,5,2’,5’-tetrachlorobiphenyl, chlorobiphenyl, 35065-27-1; 2,3,4,6,3’,4’-hexachlorobiphenyl, 35693-99-3; 2,4,2‘,4‘-tetrachlorobiphenyl,2437-79-8; 2,4,6,4’- 74472-42-7;2,3,5,6,2’,5’-hexachlorobiphenyl,52663-63-5; tetrachlorobiphenyl, 32598-12-2; 2,4,5,4’-tetrachlorobiphenyl, 2,3,4,5,6,3‘-hexachlorobiphenyl,41411-62-5; 2,3,4,5,2‘,5’-hexa2,3,4,5,6,2‘,6’-heptachlorobiphenyl, 32690-93-0; 2,3,6,4’-tetrachlorobiphenyl,52663-58-8; 2,3,5,4’- chlorobiphenyl,52712-04-6; tetrachlorobiphenyl,74472-34-7; 2,3,3’,4’-tetrachlorobiphenyl, 74472-49-4;2,3,4,6,2’,3’,5’-heptachlorobiphenyl, 40186-70-7; 52663-67-9; 2,3,4,5,3’,4’,5’41464-43-1; 2,5,3’,4’-tetrachlorobiphenyl,32598-11-1; 2,3,4,6- 2,3,5,6,2’,3’,5’-heptachlorobiphenyl, heptachlorobiphenyl,39635-31-9; 2,3,4,5,2’,3’,5’-heptachlorobitetrachlorobiphenyl,54230-22-7; 2,5,3’,5’-tetrachlorobiphenyl, 2,3,5,6,2’,4’,6’-heptachlorobiphenyl, 74487-85-7; 41464-42-0; 2,3,5,6-tetrachlorobiphenyl,33284-54-7; 3,4,5,4‘- phenyl,52663-74-8; 2,3,5,6,2‘,3‘,6‘-heptachlorobiphenyl, 52663-64-6; 2,3,4,5,2‘,3‘,6‘tetrachlorobiphenyl,70362-50-4; 2,3,4,5-tetrachlorobiphenyl, 2,3,4,6,2’,4’,5’-heptachlorobi33284-53-6; 2,3,5,2’-tetrachlorobiphenyl, 70362-46-8; 2,6,3’-tetra- heptachlorobiphenyl,38411-25-5; chlorobiphenyl, 41464-46-4;3,4,5,3’,4’-pentachlorobiphenyl, phenyl,52663-69-1; 2,3,4,5,2’,4’,6’-heptachlorobiphenyl, 60145-23-5; 57465-28-8;2,4,6,2’,6’-pentachlorobiphenyl,56558-16-8; 2,3,4,6,2’,3’,4’-heptachlorobiphenyl, 52663-71-5; 2,3,4,6,2’,4’,6’2,3,6,2‘,6’-pentachlorobiphenyl,73575-54-9; 2,3,6,2’,5’-penta- heptachlorobiphenyl,74472-48-3; 2,3,4,5,6,2’,4’-heptachlorobi2,3,4,5,2’,4’,5’-heptachlorobiphenyl, 35065-29-3; chlorobiphenyl, 38379-99-6;2,3,5,2‘,4‘-pentachlorobiphenyl, phenyl,74472-47-2; 68194-07-0;2,4,5,2‘,4‘-pentachlorobiphenyl,38380-01-7; 2,3,4,5,2’,3’,4’-heptachlorobiphenyl, 35065-30-6; 2,3,4,5,6,3’,4’2,3,5,2’,6’-pentachlorobiphenyl,73575-55-0; 2,4,5,2’,6’-penta- heptachlorobiphenyl,41411-64-7; 2,3,4,5,6,2’,5’-heptachlorobiphenyl,52712-05-7; 2,3,4,5,6,2’,3’-heptachlorobiphenyl, 68194-16-1; chlorobiphenyl, 68194-06-9;3,4,5,2’,3’-pentachlorobiphenyl, 76842-07-4;2,4,5,2’,5’-pentachlorobiphenyl,37680-73-2; 2,3,5,6,2’,4’,5’-heptachlorobiphenyl, 52663-68-0; 2,3,4,5,6,3’,5’2,3,6,2’,4’-pentachlorobiphenyl,68194-05-8;2,3,5,6,2’-penta- heptachlorobiphenyl,69782-91-8; 2,3,5,6,2’,3’,4’-heptachlorobichlorobiphenyl, 73575-56-1;2,3,5,2’,3’-pentachlorobiphenyl, phenyl,52663-70-4; 2,3,5,6,3’,4’,5’-heptachlorobiphenyl, 69782-91-8; 60145-20-2;2,3,6,2‘,3‘-pentachlorobiphenyl,52663-60-2; 2,3,4,6,3’,4’,5’-heptachlorobiphenyl, 74472-50-7; 2,3,4,5,6,2’,4’,6’2,4,5,2’,3’-pentachlorobiphenyl,41464-51-1;2,4,6,2’,5’-penta- octachlorobiphenyl,74472-52-9; 2,3,4,6,2’,3’,5’,6’-octachlorobichlorobiphenyl, 60145-21-3;2,4,6,2’,3’-pentachlorobiphenyl, phenyl,40186-71-8; 2,3,4,5,6,2’,3’,4’-octachlorobiphenyl, 52663-78-2; 60233-25-2;2,3,5,3‘,5‘-pentachlorobiphenyl, 39635-32-0; 2,3,4,5,2’,3’,5’,6’-octachlorobiphenyl, 52663-75-9; 2,4,5,3‘,5‘-pentachlorobiphenyl, 68194-12-7; 2,4,5,3’,4’-penta- 2,3,5,6,2’,3’,5’,6’-octachlorobiphenyl, 2136-99-4; chlorobiphenyl, 31508-00-6;2,4,6,2’,4’-pentachlorobiphenyl, 2,3,4,5,2’,3’,4’,6’-octachlorobiphenyl, 42740-50-1; 39485-83-1;2,3,4,3’,4’-pentachlorobiphenyl,32598-14-4; 2,3,4,6,2’,3’,4’,6’-octachlorobiphenyl, 33091-17-7; 2,3,4,6,2’-pentachlorobiphenyl, 55215-17-3; 2,4,6,3’,5’-penta- 2,3,4,5,2’,3’,4’,5’-octachlorobiphenyl, 35694-08-7; chlorobiphenyl, 56558-18-0;2,3,4,2’,4’-pentachlorobiphenyl, 2,3,4,5,6,2’,3’,5’-octachlorobiphenyl, 68194-17-2; 65510-45-4;2,3,4,3’,5’-pentachlorobiphenyl,70362-41-3; 2,3,4,5,6,2’,3’,6’-octachlorobiphenyl, 52663-73-7; 3,4,5,3‘,5‘-pentachlorobiphenyl,39635-33-1;2,3,4,6,4’-penta- 2,3,4,5,6,3’,4‘,5’-octachlorobiphenyl, 74472-53-0; chlorobiphenyl, 74472-38-1;3,4,5,2’,4’-pentachlorobiphenyl, 2,3,4,5,6,2’,4’,5’-octachlorobiphenyl, 52663-76-0; 65510-44-3;2,4,6,3‘,4’-pentachlorobiphenyl,56558-17-9; 2,3,4,5,6,2’,3’,5’,6’-nonachlorobiphenyl, 5121-88-0; 2,3,5,6,3’-pentachlorobiphenyl, 74472-36-9;2,3,4,2’,3’-penta- 2,3,4,5,6,2‘,3’,4’,5‘-nonachlorobiphenyl, 40186-72-9; chlorobiphenyl, 52663-62-4;2,3,6,3‘,5’-pentachlorobiphenyl, 2,3,4,5,6,2’,3’,4’,6’-nonachlorobiphenyl,52663-79-3; 68194-10-5;2,3,4,5,2’-pentachlorobiphenyl,55312-69-1; 2,3,4,5,6,2’,3’,4’,5’,6’-decachlorobiphenyl, 2051-24-3. 2,3,5,6,4’-pentachlorobiphenyl,68194-11-6;2,3,4,5,3’-pentaLITERATURE CITED chlorobiphenyl, 70424-69-0;2,3,4,2’,5’-pentachlorobiphenyl, 38380-02-8;3,4,5,2’,5’-pentachlorobiphenyl, 70424-70-3; (1) Pellizzari, Edo D.; Moseley, M. Arthur; CooDer, SteDhen D. Chromatogr. Rev., in press. 2,3,4,6,3’-pentachlorobiphenyl,74472-35-8;2,3,4,5,4’-penta(2) Mullin, Michael D.; Pochini, Cynthia M.; McCrindle, Sheila; Romkes, chlorobiphenyl, 74472-37-0;2,3,4,2’,6‘-pentachlorobiphenyl, Marjorie; Safe, Stephen H.; Safe, Lorna M. Environ. Sci. Techno/. 73575-57-2;2,3,4,5,6-pentachlorobiphenyl,18259-05-7; 1984, 18, 468-76. 2,3,5,2’,5’-pentachlorobiphenyl,52663-61-3; 2,3,6,2’,4’,5’-hexa- (3) Cairns, Thomas; Siegmund, Emil G. Anal. Chem. 1981, 5 3 , 1183A93A. chlorobiphenyl, 38380-04-0; 2,3,5,2’,4’,5’-hexachlorobiphenyl, 51908-16-8;2,3,6,2’,4’,6’-hexachlorobiphenyl, 68194-08-1; 2,3,4,6,2’,3’-hexachlorobiphenyl, 61798-70-7; 2,3,5,2’,4’,6’-hexa- RECEIVED for review April 22,1985.Accepted June 28,1985. chlorobiphenyl, 74472-41-6; 2,4,6,2’,4’,6’-hexachlorobiphenyl, Although the research described in this article has been funded 33979-03-2;2,3,4,2’,3’,4’-hexachlorobiphenyl, 38380-07-3; wholly or i n part by the US.Environmental Protection 2,3,6,2’,3’,6’-hexachlorobiphenyl, 38411-22-2; 2,3,4,6,2’,6’-hexaAgency through Contract No. 68-03-3099to the Research chlorobiphenyl, 74472-40-5; 2,3,5,6,3’,5’-hexachlorobiphenyl, 74472-46-1;2,3,4,2‘,3’,6’-hexachlorobiphenyl,38380-05-1; Triangle Institute,it has not been subjected to the Agency’s 2,3,4,2’,3’,5’-hexachlorobiphenyl,52663-66-8; 2,3,5,6,2’,6’-hexa- required peer and administrative review and therefore does chlorobiphenyl,68194-09-2; 2,4,5,2‘,4’,6‘-hexachlorobiphenyl, not necessarily reflect the views of the Agency,and no official 60145-22-4;3,4,5,3’,4’,5’-hexachlorobiphenyl, 32774-16-6; endoresement should be inferred.
