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466 JOURNAL OF THE aoac (Vol. 55, No. 3, 1975) Limitation on the Use of Antimony Pentachloride for Perchlorination of Polychlorinated Biphenyls WILLIAM J. TROTTER and SUSAN J. V. YOUNG Division of Chemistry and Physics, Food and Drug Administration, Washington, DC 20204 Two contaminants are present in commer (SbCls). The method provides a qualitative cially available antimony pentachloride (SbClj) confirmatory procedure for PCB determination. used to perchlorinate polychlorinated biphenyls (PCBs) to decachlorobiplienyl (DCB). DCB is found in the SbClg perchlorination reaction blank in which no PCBs were added. Brumo- . nonachlorobiphenyl (liNCB) is found after use of SbClj to perchlorinate PCBs. Levels of DCB found in the SbClj reaction blanks from vari ous distributors ranged from 8 to 972 ng DCB/ ml SbClj. The relationship of the formation of The GLC electron capture detector response is enhanced because total PCBs are manifested as a single peak for DCB. In measuring the single peak for DCB the analyst is not faced with analytical judgments such as baseline correction, method of integration, or discrimination between PCBs and non-PCB components. However, it is necessary to be aware that the various Aroclors BKCB to amounts of various PCB Aroclors give rise to different equivalents of DCB (6) perchlorinated is examined. and that the nonchlorinatcd biphenyl (also used as j.-iMnlormatecl by' oL'i3 to Polychlorinated biphenyl (PCBs) residues are rfCiy!' Nonetheless, 1 using"*TTieier"h[orTuai".in extracted, cleaned tip, and detected by methods SerTvatization can reinforce the,residue value similar to those used for organochlorine pesti determined by measuring a multicomponent cides. PCB residues are quantitatively deter PCB residue. mined by comparing the gas-liquid chromato During attempts to apply the perchlorination graphic (GLC) response of the multicomponent derivatization in determining low residue levels residue and commercial PCBs (Arcelor) or a of PCB and make use of the increased electron mixture of Aroclors producing a GLC response capture response to DCB, 2 contaminants were pattern similar to that of the residue (1). This indicated which led to erratic recoveries of DCB. approach is limited because the multicomponent PCB residue may not have the same propor Experimental tional composition as the Aroclor or Aroclors Reagents and Apparatus used as the quantitation reference. Residues can be composed of mixtures of chlorobiphenyl com ponents from more than 1 Aroclor. Metabolic and other environmental factors complicate the description of the PCB residue composition. There has been considerable work to develop methods to convert the multicomponent PCBs to a single derivative on which to base the resi due determination. Procedures have been re (a) Antimony pentachloride.--Hooker Chemical, Niagara Falls, NY 14302 (received in glass bottle with lead-lined cap) ; Matheson Coleman & Bell (MCB), Norwood, OH 45212 (reagent grade); B&A (Allied Chemical), Morristown, NJ 07950 (reagent grade, 90%); Research Organic-Inorganic Chemical (ROC-RIC), Belleville, NJ 07109 (99:99%).; and J. T. Baker Chemical, Phillipsburg, NJ 0SS65 (Baker Analyzed Reagent). (b) Cos chromatograph.--Searle-Analytic (Dess ported to catalytically dechlorinate PCBs with - Plaines, IL 600SS) Model 5360 with 6' X 4 mm id hydrogen over palladium or platinum to bi glass column containing 1% OV-101 on 80-100 phenyl, cyclohexvlbenzene, and bicyclohexyl (2, 3). A principal disadvantage with that pro cedure is that the hydrocarbon product is determined with a GLC flame ionization detec tor. resulting in low sensitivity. Attempts have been made to convert PCBs to the fully chlor inated decachlorobiphenyl (DCB) (3-5). Ar mour (6) reported optimum conditions for p?rcldorinating PCBs with antimony pentachloride mesh Chromosorb W (HP). Operating conditions: column flow, 60 ml nitrogen/min; column, 202C; detector, 202aG; injector, 225C; pin-cup design electron capture detector with titanium 3H foil; detector vol rage (constant dc) adjusted to cause one-half full scale recorder deflection for 0.7 ng DCB when full scale deflection is 1 X 10- amp. (c) Mass spectrometer.--Varian MAT (25 Route 22, Springfield, NJ 07081) CII5-DF mass spectrom eter (MS) coupled to Vnrian Aerograph 2740 gas rr ch Ei o:. cc. Veir in inr. o? vrz of be- Vr thter cr. ex. in G? rjv F-:- in:. fn* Th to WTi IX in liir. StL cic pe: of ch- Ho MC Bi FC J. OS\N 297 6^7 -'V STLCOPCB4067550 nYiri t rfl wnifiifVi ir mVi iT> wifi" Ti' rmlri ' u n i *0-Va*trjn+z usLrL.*x** ; i TROTTER 4 YOUNG: PERCHLORINATION OF PCB* 467 chromatograph viA all-glass system using WatsonBiemann 2-stage separator. GI.C operating condi ' tions: 6'X 4 mm id glass column containing 3% OV-I on 80-100 mesh Chromosorb W (HP); column flow, 60 ml helium/min; column 240C. MS operating conditions: electron energy, 70 ev; emission current, 300 /*&; multiplier voltage, 2.2 kv. ' . " Results and Discussion ?'" A peak identical to that of DCB teas found in the reaction blank for the Armour perchlor- ination procedure (6) tvith the described GLC . operating conditions. The identification of DCB was confirmed by GLC-M5 of a hexane extract of a hydrolyzed sample of SbCIs which had not been subjected to the perchlorination procedure. Various quantities (05-2.0 ml) of SbClj from the 5 commercial sources Were examined to de termine the presence of DCB. SbClj alone was carried through the perchlorination reaction (6) except that no CHC1, was present with SbCls FIG. 1--Electron capture GLC curve from the 0.2 ml SbClj (Hooker Chemical) perchlorination of 0.50 MS Aroclor 1221; 0.51 ng equivalent Aroclor 1221 injected. Peak 1 represents 0.81 ng OC8. Peak 2 represents 0.28 tig BNCB. in the reaction vessel. DCB was determined by GLC. Table 1 lists the amounts of DCB found. amounts of BNCB product formed was based After perchlorinating PCBs with SbCl5, a on comparison of the electron capture GLC peak secondary peak with a GLC retention time rela height of BNCB with that of a DCB reference. tive to DCB of 151 was observed similar to that The amount of DCB determined in the reac reported by Huckins et al. (7). This later eluting tion blank was directly proportional to the peak is seen in Fig. 1, the chromatogram from amount of SbClj used (Table 1). This indicates *be 0.2 ml SbCl5 (Hooker Chemical) perchlor SbClj was the source of the DCB and that ination of 0.50 p.g Aroclor 1221. This peak W-as contamination from other possible sources dur found when bijilij irorn each supplier was used. ing the perchlorination was negligible. The pro The peak was determined by GLC-MS to be due cedure for perchlorinating PCBs specifies the to bromononachlorobiphenyl (BNCB). BNCB use of 05 ml SbCls. SbCU producing S-072 was assumed to be a competing product with SbCl5/ml in the reaction blank would add 0.5 DCB arising from a small amount of SbCl,Br 65 ppb, based on a 3 ^ sample. in SbClj, so parameters relating to possible - DCB produced in the reactiotrbiank was as- limitations.of the perchlorination procedure were -- sumed-to come from PCB contamination of studied. Various quantities (0.5-10 /ig) of Aro- SbClj. In an effort to locate the origin of this clors 1221, 1242, 1254, and 1260 in CHC13 were contamination, SbCl5 bottle closures were investi perchlorinated. Recoveries of DCB and estimates gated, GLC analysis of hexane, in which the of the relative amounts of BNCB formed are plastic caps were soaked for 4 days, did not given in Table 2. Calculation of the relative reveal PCBs. Hooker Chemical, the sole do mestic source of SbCI5, supplied SbClj in glass Tab!* I. DCB (ng/ml) formed from varfoua ;. amounts of SbClj bottles with lead-lined caps. This bulk supplier of SbClj indicated that the production of chlo rine in carbon anode half-cells with linseed oil SbClj, ml or other organic binders forms certain organic Supplier 0.2 1.0 2.0 Av. compounds; however, the destructive oxidative Hooker Chemical MCB ^B&A ROC-RIC J. T Baker environment in the electrolytic cells would make 37 35 44 42 47 33 43 38 the production of PCB unlikely as a result of this 960 1042 913 972 pathway. On the other hand, antimony metal is 12 9 13 7 12 12 commonly obtained ns a metallurgical by-prod 7f uct by carbon reduction of its oxide; therefore. / ! l :\ ' '. ; I oSvj*rt638 STLCOPCB4067551 .... , ,-p----, 468 JOURNAL OP THE AOAC (Vol. 5S, No. 3, 1975) Table 2. DCB and BNCB from parchlorlnatlon of various Aroclors with 0.2 ml SbClj* Aroclor Amt. MS OCB reed, % BNCB' reed, % DCB + BNCB' combined rec. % 1260 1254 1242 1221 ,10 - os - ' 0 10 64 o 10 8 4 . u . 67 16 ; .86 . 64 92 83 - ' 1260 1254 1242 1221 fC 4 .' -4 . .. 4 ,4 , 41 SO 78 70 0 o ' 8 18 : ' 81 eo 66 ' 68 1260 0.5 89 2 ' 91 - 1254 0.5 78 ' 6 - - 84 1242 0.5 72 10 82 1221 0.5 60 19 79 * Hooker Chemical SbClj. * Quantity calculated by comparison of electron.cap ture GLC response to BNCB vs. response to DCB refer, ence standard. ,. ,: it is conceivable that PCBs could be associated with the antimony metal employed in the SbCls process. No heat transfer systems containing PCBs are used in either the chlorine or SbCI5 production facilities, and SbCl5 does not come into contact with plastics in the manufacturing operation or in shipping containers (Hooker Chemical and Plastics Corp., 1974, private com munication). Two parameters (various quantities and vari ous Aroclors) were studied in relationship to the production of BNCB as a competing prod uct of DCB during the pcrchlorination of PCBs. BNCB was calculated by comparison of the elec tron capture GLC response to BNCB vs. the response to DCB. Several factors are considered: (/) In this reaction bromination is kineticallv favored over chlorination. With perchlorinatiori of lower amounts of PCBs the relative yield of BNCB to DCB is greater because the bromin- ating agent is the limiting quantity in contam inated SbCl*. (2) Bromination occurs to a larger degree for a given quantity of the less chlori nated PCBs euch as Aroclors 1221 and 1242. rather than for 1254 and 1260. This likely is due to a greater number of reactive sites and less steric hindrance. (3) In the range of PCBs per-, chlorinated (0.5-10 pg) in the above study, it is likely that with lower amounts of PCBs and/ or less chlorinated Aroclors the decrease in DCB recovery is principally due to the increase of BNCB formed. " ~ - One of the major advantages of perchlorina- tion in determining minute quantities of PCBs is the inherent increase in effective GLC detec tor response. Contaminated SbCls, as described here, would preclude its use in many of these cases. References (1) Official Methods oj Analysis (1975) 12th Ed, AOAC, Washington, DC, secs. 29.001-29.007 (2) Asai, R, Gunther, R, Westlake, W, & Iwata, - Y. (1971) J. Ayr. Food Chem. 19, 396-39S (3) Berg, O. W, Diosady, P. L, & Rees, G. A. V. (1972) Bull. Environ. Contam. Toxicol. 7, 33S-347 (4) Hutzinger, O. W, Safe, S, & Zitko, V. (1972) Ini. J. Environ. Anal. Chem. 2, 95-106 (5) Hutzinger, O. W, Jamieson, D, Safe, S, & Zitko, V, (1973) JAOAC 56, 9S2-9S6 (6) Armour, J. A. (1973) JAOAC 56, 9S7-993 (7) Iluckins, J. N, Swanson, J. E., & Stalling, D. L. (1974) JAOAC 57, 416-417 Received AugUtft 21, 1971. . . Thu pnpfr was presented at the SSth Annual Meeting of the AOAC, Oct. M-17,. 1974, at Washington. DC. . COPPOL. Fluorc ELIA D. The Coi.! An imi mining fc tented. T; in a dia. excess of acts selet sulfanilic excess an by difTerr is direcil; of the se and solu: eliminate in the flu 495 nm i ment at dium nitr an avera;: of 5.23 The additive;, in the Ur lion pour, salami, fr. are prod there ha.? tential he additives nitrite, re in the be; (i-3). t: limited 'o: 200 ppm There nitrite in method f colorimet: 13 diazoti; to form a method w by Nicho' factory. I expressed th\'iamine the non-c: v I'.yw. DSW 297639 yrpg STLCOPCB4067552