2014
Anal. Chem. 1086, 58,2014-2022
chloride, 7791-11-9; cesium chloride, 7647-17-8; triethylamine, 121-44-8;diethanol amine, 111-42-2;diethanolamine hydrochloride, 14426-21-2. LITERATURE CITED Barber, M.; Bordoli, R. S.; Sedgwick, R. D.; Tyler, A. N. J. Chem. Soc., Chem. Commun. 1981, 325-327.
McNeal. C. J. Anal. Chem. 1982, 5 4 , 43A. MacFarlane, R. D. Acc. Chem. Res. 1982, 15, 268-275. A' Int'J '
Ion
1983' 46' 459'
Magee, C. W. Int. J. Mass Spectrom. Ion h y s . 1983, 49, 211.
Garrison, B. J. J. Am. Chem. SOC.1982, 704, 6211. Busch, K. L.; Unger, S. E.; Vlntze, A.; Cooks, R. G.; Keough, T. J . Am. Chem. Soc. 1982. 104. 1507. Inchaouh, J.; Blais, J. C:; Bolbach, B.; Brunot, A. Znt. J . Mass Spectrom. Ion Processes 1984, 6 1 , 153. Sunner, J. A.: Kulatunga, R.; Kebarle, P. Anal. Chem. 1986, 5 8 , 1312-1316. Michl, J. I n t . J . Mass Spectrom. Ion Phys. 1983, 5 3 , 255.
(11) van der Peyl, G. J. 0.;Isa, K.: Haverkamp, J.; Klstemaker. P. G. Org. Mass Spechom. 1981. 76, 416. (12) Cooks, R. G.; Busch, K. L. Int. J. Mass Spectrom. Ion Processes 1983. 5 3 , 111-124. (13) Garrlson, 8. J.; Winograd, N.; Harrison, D. E., Jr. J. Chem. Phys. 1978 6 9 , 1440. (14) Hogg, A. M. Int. J. MssSpectrom. IonPhys. 1983, 49, 25. (15) Freeman, G. R. Radlat. Res. Rev. 1988, 7 , 20. (16) Wagman, D. D.; Evans, W. H.; Parker, V. B.; Schumm, R. H.; Halow, I.; Balley, S. M.; Churney, K. L.; Nuttall, R. L. J. Phys. Chem. Ref. Data 1882, I f , Suppl. 2. (17) DzMic, I.; Kebarle, P. J. wys. Chem. 1870, 74, 1466-1474. (18) van der Peyl, G. J. Q.; van der Zande, W. J.; Hoo@xupge, R.; Klstemaker, P. G. Int. J. Mass Spectrom. Ion Processes 1985, 6 7 , 147-159.
RECEIVED for review November 22,1985. Accepted April 15, 1986. The present work was supported by a grant from the Canadian Natural Sciences and Engineering Research Council.
Characterization of Commercial Aroclors by Automated Mass Spectrometric Determination of Polychlorinated Biphenyls by Level of Chlorination Ann L. Alford-Stevens,* T h o m a s A. Bellar, J a m e s W. Eichelberger, and William L. Budde
Environmental Monitoring and Support Laboratory, Office of Research and Development, Protection Agency, 26 West St. Clair Street, Cincinnati, Ohio 45268
Determlnatlon of polycMorlnated blphenyk (PCBs) by level of cMorlnation p r o w dkungulshlng characterlstlc features for nine Aroclor fonnutatlonr that are available as reference materlak. ImlhrMual PCB compmmts that were present In sutficlent qusnttty to be detected and measured In 100 ng of each Aroclor mMure were dlstlngulshed by level of chlorlnatlon, relative retenth thne, and rolatlve abundance. Wlth data acquhed In thls study, lndivldual Aroclors can be detennined wllh relative ease, and mixed A r d o r detennlnatkns are powlble but Impractical for routlne analyses of envlronmental samples. The accuracy of PCB determlnatlons with this approach depends on the slmllarity of InJected quantities of sample extracts and sdutlons containlng reference Aroctors. Detectlon llmlts were estimated for lndlvldual components of Isomer groups measured In extracts of reagent water fortified with mixed Aroclors.
An approach to determination of polychlorinated biphenyls (PCBs) by identification and measurement of isomer groups was previously described in detail (1). That approach requires the use of one internal standard and nine individual PCBs to calibrate the mass spectrometer (MS) response to sample components eluting from a fused silica capillary column in a gas chromatograph (GC). The MS detector distinguishes among PCBs with different levels of chlorination. One isomer from each level is used to calibrate the MS response to all isomers in that group, except that decachlorobiphenyl is used for both nona- and decachlorobiphenyls. Automated identification and measurement of PCBs are performed with specialized software that has been described in a previous report (2). The software operates on a dedicated minicom-
US.Environmental
puter and handles unprocessed GC/MS data without human interaction. This approach not only produces accurate, precise, and cost-effectivePCB determinations (2) but also has the distinct advantage of permitting determination of PCBs in all types of samples. It can be applied to samples containing commercial PCB formulations (manufactured and sold in the United States by the name Aroclors), metabolized or environmentally altered Aroclors, or non-Aroclor PCBs (such as incidentally generated PCBs). Aroclor mixtures have been characterized with various GC detectors, such as electron capture and flame ionization (3-11) as well as MS (12-15). Results have varied with the type of GC column available for separation of Aroclor components and with the approach to detector calibration. Aroclors have not, however, been characterized by level of chlorination with the nine PCB congeners carefully selected (1)to calibrate the MS detector. This report presents results obtained when that approach was used to characterize nine Aroclor formulations that are available for use as reference materials. Although individual PCBs were not specifically identified, this GC/MS approach provided other valuable information, including the relative retention time, relative abundance, and level of chlorination of the congener(s) represented by each GC peak. Acquired data were used to identify and measure Aroclors in two solutions, one containing four Aroclor mixtures and one containing seven Aroclor mixtures. EXPERIMENTAL S E C T I O N
Materials. The nine PCB calibration congeners were obtained from Ultra Scientific, Hope, RI, and were used without purification. The internal standard, chrysene-d,,, was obtained from Aldrich Chemical Co., Milwaukee, WI. A single-componentsolution of each of the nine PCB concentration calibration congeners
This article not subject to US. Copyright. Published 1986 by the American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 58, NO. 9, AUGUST 1986
Table I. Composition and Approximate Concentrations of Calibration Solutions PCB isomer group/ internal standard ClI-PCBs Clz-PCBs C1,yPCBs Cld-PCBs C15-PCBs Cle-PCBs ClT-PCBs Cls-PCBs ClS-PCBs' CliO-PCB chrysene-dI2
chlorine substitution
concentration, ng/pL 1
2
0.5 0.5 0.5 1
2.5 2.5 2.5 5 5 5 7.5 7.5
3
4
5 5 5 10 10 10 15 15
20 20 20 30 30
25 25 25 50 50 50 75 75
2,2',3,3',4,4',5,5',6,6' 2.5 12.5 25
50
125
2 2,3 243 2,2',4,6 2,2',3,4,5' 2,2',4,4',5,6' 2,2',3,4',5,6,6' 2,2',3,3',4,5',6,6'
1 1
1.5 1.5
7.5
7.5
7.5
10 10
5
10
7.5
7.5
Decachlorobiphenyl is used as the calibration congener for both nona- and decachlorobiphenyl isomer groups. and the internal standard, chrysene-d,,, was prepared by weighing pure compounds and dissolving them in hexane. Three multicomponent calibration solutions were then prepared by combining appropriate aliquots of the single-componentsolutions to provide the concentrations needed for GC/MS data acquisition. The composition of calibration solutions is shown in Table I. Solutions of Aroclors 1221, 1232,1016,1242, 1248,1254,1260, 1262, and 1268 were obtained as Quality Assurance Technical Materials (>95% purity) from the U.S. Environmental Protection Agency (USEPA) Repository for Toxic and Hazardous Materials, Environmental Monitoring and Support Laboratory, USEPA, Cincinnati, OH. Each Aroclor solution (5OOOpg/mL in methanol) was diluted with hexane to provide solutions of appropriate concentrations for analysis of 2-pL aliquots. Each resulting solution contained the internal standard at a concentration of 7.5 ng/pL. Aroclors (1221, 1242, 1254, and 1268) used to fortify reagent water were diluted with acetone to provide appropriate concentrations when a 1-mL aliquot was added to 1-L of reagent water. Reagent water was prepared by passing distilled water through a column containing about 450 g of granular activated carbon. An additional formulation of Aroclor 1242 (lot number unavailable) that had been obtained in the early 1970s from Ronald Webb of the USEPA Environmental Research Laboratory, Athens, GA, was diluted in hexane to provide a 50 ng/pL solution. Water Extracts. Eight 1-L aliquots of reagent water were placed in a series of 2-L separatory funnels. To each of seven aliquots was added 1mL of the standard solution of Aroclors in acetone. After being shaken, each fortified water sample was allowed to stand for at least 1 h. Each 1-L sample was extracted (without pH adjustment) with three sequential 60-mL portions of methylene chloride. Each extract was dried by passing it through a column of purified anhydrous sodium sulfate and concentrated to about 6 mL with a Kuderna-Danish apparatus. After solvent exchange to hexane, each extract was concentrated to a final volume of 1 mL, and a 20-pL aliquot of the solution containing 375 ng/pL of the internal standard (IS), chrysene-d12, was added just before GC/MS analysis. A 2-pL aliquot was analyzed with the GC/MS conditions described below. The eighth reagent water aliquot served as a reagent blank and was carried through all operations except addition of the solution of Aroclors. Instrumentation and Analytical Conditions. Mass spectral data were obtained with a Finnigan Model 4500 MS operated in the electron ionization mode (nominal 70 eV) and interfaced with a Carlo Erba Model 5160 GC equipped with an on-column injector and a splitless injector. Separations were accomplished with a 30 m X 0.32 mm i.d. fused silica capillary column coated with a 0.25-pm film of cross-linked phenylmethylsilicone (Durabond-5, J and W Scientific, Rancho Cordova, CA). For on-column injections, a precolumn (retention gap) was connected to the injection port end of the analytical column. The precolumn, a 1.5-m length of 0.32 mm i.d. uncoated fused silica tubing (Altech Associates, Deerfield, IL), was connected to the analytical column with a stainless steel, zero-dead-volumeunion with 1/32-in.Vespel
2015
ferrules (Valco, Houston,.TX). Before installation, the precolumn was deactivated by passing approximately 20 mL of Sylon-CT reagent (Supelco, Inc., Bellefonte, PA) through the tubing with vacuum suction. On-column injections of 2-pL aliquots of calibration and Aroclor solutions were performed with the oven temperature at
