Document 55xYk1D5Z4o2RyYaMRXj4YeJ

/ (" * STUDY OF AROCLOR CHEMICAL CLEAN-UP PROCEDURES FOR USE . WITH ELECTRON CAPTURE GAS CHROMATOGRAPHY METHODS INTRODUCTION The effects of three chemical clean-up procedures on the Aroclor 1200 series have been investigated. The chemical procedures in question; nitration, saponification, and treatment with sulfuric acid were orig inally proposed by pesticide analysts for the cleanup and identifica tion of pesticides in residue extracts. Later when polychlorinated biphenyls (PCB's) were identified as environmental contaminants these procedures were extended-to the clean-up and identification of PCB's in residue extracts. . -. SUMMARY 1. The quantitative recovery and EC response of Aroclors are not effected by saponification or treatment with sulfuric acid. 2. Nitration can have a significant deleterious effect on the quantitative recovery and EC response of Aroclor 1242. * * 3. The extent of the effect of the nitration treatment is dependent on the temperature and exposure time employed as well as the Aroclor treated. 4. Analysts employing nitration.procedures prior to EC analysis may or may not, depending on the conditions used, see an EC response for Aroclor 1242 if present. DISCUSSION We have found that saponification and treatment with sulfuric acid . do not effect the quantitative recovery nor the electron capture (EC) response of the Aroclors. However, the nitration procedures have significant deleterious effects on both the quantitative recovery and EC response of the lower chlorinated biphenyls such as Aroclor 1242. The effect of this treatment on the Aroclors are shown graphically in Figures 1-7. The fact that the lower chlorinated biphenyls are .nitrated under these conditions has been verified by GC/Mass Identification of the products as nitrochlorobiphenyIs. The nitration procedure employed was referenced by Risebrough* [Erro, F., Bevenue, A., and Beckman, H., Bull. Environ. Cont. Toxicol., 372 (1967)] in his Nature article on PCB residues in the environment. Additional, we have investigated a similar nitration procedure used by Widmark and co-workers (private communication via R. E. Reller). This treatment differs from Risebrough's in that a shorter exposure time and a lower temperature are employed. The Widmark method greatly diminishes the effects observed with Risebrough's referenced method. 60014?? WATER PCB-SD0000041659 t:::: m V. STUDY OF AROCLOR CHEMICAL CLEAN-UP PROCEDURES Page 2 RESULTS Verification of the conclusions drawn are shown in Figures 1-7. Extraction and measurement were performed as described in Analytical Method No. 69-13. '' * *A quote from Risebrough's article [Nature, 220, 1098 (1968)], "The DDT compounds are destroyed by nitration and p,p'-DDT, DDD, and toxapbene are dehydrochlorinated by saponification with alcoholic KOH. PCB is not degraded by either.procedure." db ... Monsanto Company Organic Chemicals Division Applied Sciences Section St. Louis, Missouri . ' ; . ' `` ' 3-70 - E. S. Tucker, W. J. Lit^chgi, R. E. Keller / 0001478 WATER PCB-SD0000041660 FIGURE 1. . . . . Electron capture gas chromatographic trace of (A) biphenyl treated with 1:1 mixture of nitric and sulfuric acids and extracted into hexane, (B) biphenyl treated with distilled water and extracted into hexane, and (C) untreated biphenyl standard in hexane. 0001479 WATER PCB-SD0000041661 AROCLOR 1242 FIGURE 2. Electron capture gas chromatographic trace of (A)' Aroclor 124 2 ar.d treated . with 1:1 mixture of nitric and sulfuric * acids and extracted into hexane, (3) -' ' Aroclor 1242 treated with distilled ' ;' water and extracted into hexar.e, and (C) untreated,Aroclor 124 2 standard in ; - hexane. ' 0001480 WATER PCB-SD0000041662  AROCLOR 12 4 S FIGURE 3. .' . Electron capture cas chromatographic trace of (A) Aroclor 1248 treated with 1:1 mixture of nitric and sulfuric acids and extracted into hexane> (B) Aroclor 1248 treated with _ distilled water and extracted into hexane., and (C) untreated Aroclor. 124 8 standard in hexane. . 0001481 WATER PCB-SD0000041663 V. J O' / FIGURE ' '. 4. ` Electron capture gas chromatographic trace of (A) Aroclor 1254 treated with 1:1 mixture of nitric and sulfuric acids and extracted into hexane, (E) Aroclor 1254 treated with distilled water and extracted into hexane, and (C) untreated Aroclor 1254 standard in hexane. 0001482 WATER PCB-SD0000041664 X+ FIGURE 4. ' ' .` Electron capture gas chromatographic trace of (A) Aroclor 1254 treated with 1:1 mixture of nitric and sulfuric acids and extracted into hexane, (S) ArocJLor 1254 treated v;ith distilled water and extracted into hexane, and ((E) untreated Aroclor 1254 standard in hexane. . 0001483 WATER PCB-SD0000041665 /U V U V JJV /1 V FIGURE 5 . .. 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