Document mBX9y7p1KwLgz1zd3YEXeMNbb

Not for Publication Presented Before the Division of Water, Air and Waste Chemistry American Chemical Society New York, August, 1972 Identification of PCB's in the Presence of DDT-Type Compounds Using Low Temperature Luminescence J. T. Brownrigg, J. Guilfoyle and A. W. Hornig Baird-Atomic, Inc. 125 Middlesex Turnpike Bedford, Mass. 01730 INTRODUCTION Polychlorinated biphenyls (PCB's) have emerged as ubiquitous environmental pollutants having been widely used as plasticisers, lubricants, flame retardants, and as heat transfer media (1,2). These compounds are insoluble in water, but are soluble In lipids. PCB levels found in fish typically range from 0. 01 to I 0 ppm and from 1 to 100 ppm in flsh-eating birds and are comparable to DDE levels found in the same species (3, 5). The presence of PCB's in the environment is a matter of concern for two reasons. First, (hey have been found to be highly toxic to certain marine animals. For example, exposure for 4# hourstoO. 1 ppm Aroclor 1254 (a commercial PCB mixture) in sea water pro duces 100% mortality in juvenile pink shrimp, and strongly depresses the rate of shell growth In oyetera (6). Second, PCB'a have been found to Interfere with gas chromato graphic determination of DDT and related compounds, requiring a pre-separation step which usually Involves thin-layer or column chromatography (3). The objective of the present investigation was to assess the applicability of low temperature (77* K) luminescence spectroscopy to the problem of identifying the PCB' e In the presence of DDT-type compound#. Basic studies completed to date have focused upon the documenta tion of Important pesticide and PCB apectra, including various mixtures of these. The results obtained are very encouraging and suggest that a rapid and sensitive method for PCB determination can be developed using this approach. * EXPERIMENTAL ' The p,p'- and o,p*-derivatives of DDD, DDE, and DDT were obtained from the EPA Primate Research Branch, Perrlne, Florida. PCB isomers studied have Included biphenyl; 2- and 4-chlorobiphenyl; 4, 4' -dlchlorobiphenyl; 2, 5, 2', 5*-tetrachlorobiphanyl: 2, 4, 5, 2', 5'-pentachlorobiphenyl; and 2,4, 5, 2', 4', S'-hexachloroblphenyl. With the exception of biphenyl (Aldrich Chemical Co. ) samples were obtained from Dra. R. G. Webb and O. Hutcingar. All of these compounds have been Identified in commercial PCB mixtures (7-9). Semples of Aroclor 1221, 1242. 1249, 1254, and 1260 were provided by Drs. R. G. Webb tnd E, S. Tucker. Msthyleyclohexane, hexane, and heptane were Matheson, Coleman, and Bell Spectroquality grade solvents. Methyleyclohexane (MCH) forme a clear, rigid glass upon cooling slowly (about two minutes) to 77* K. Under similar conditions, the n-alkane matrices produce highly scattering "snows* and are therefore lees suitable for quantitative studies. MQNS 042575 66- Lumlnescenee measurement* were performed using a Baird-Atomic SF-100 {or SF-I) Fluoriipec fluorescence spectrophotometer. RESULTS 1 In general, halogenation results In diminished fluorescence yields and enhanced phospl escence yields, probably a result of enhanced inter system-crossing rates (10,11 ). Re temperature lumineecence measurement is less useful for these compounds since phot phoretcence emission is quenched. At low temperature, phosphorescence appears, an spectra are often more highly structured. All spectra appearing in this paper were obtained at 77* K, and have not been corrected for instrumental responsa. PCB Isomers ^ Emission spectra of biphenyl, 4-chlorobiphenyl, and 4,4*-dlchloroblphenyl wara found | ba coneiderably sharper in heptane than inmethylcyclohexane(MCH). Spectra of the 4.4 Isomer in these two solvents appear in Figures 1 and 2. {Spectra obtained using hexane wara very slightly broader than in heptane.) The sharper vibronic structure revealed ii the n-alkane matrices is an example of quasilinaar spectra, often called the "Shpolskii" effect (!). Usually, quasilinaar spectra are obtained In n-alkane matrices whose mole culee have dimension# similar to that of the guest (solute) molecule, and spectral band- widths become Increasingly narrow as the temperature is reduced. This phenomenon ia extremely useful for identification purposes, since narrowing results in enhanced speci ficity and sensitivity. 1 In contrast, spectra of 2-chloroblphenyI and the more highly chlorinated isomers displa rather dtffuea emission both in MCH and in heptane. Spectra of 2, 5, 2', S' -tetrachlorobiphenyl in these solvents appear in Figures 3 and 4. Since the seme isomer was found to exhibit similar diffuse emission in octane and nonane matrices as well, die emission of this isomer mhy ba intrinsically diffuse. PCB Mixtures (Aroclors) Absorption commences in the 290-300 nm region for the Aroclors studied, with phosphor' escence maxima in the region 440-480 nm. The speetrum of Aroclor 1254 in MCH at 77* is fairly typical, and la shown in Figure 5. Solvent effects noted above for PCB isomers are reflected In the speetra of Aroclors. For example, the emission spectrum of Aroclor 1221 in heptane at 77* K revealed eonsid-l arable fine structure which did not appear in MCH. Comparison with isomer spectre (in 1 heptane) Identified biphenyl and 4-chlorobiphenyl as principal constituents of this Aroclor (1221). In contrast, the emission spectra obtained for Aroclor 1248 were diffuse both in MCH and in heptane, paralleling the result obtained for 2,5, 2*, 5* -tatrachlorobiphenyl (Figures 3 and 4). It seems likely that spectra of Aroclors having even greater chlorine content will also remain diffusa in heptane so diet for these compounds MCH would be ss equally suitable matrix. Heptane, however, should prove useful- in helping to idantl/y Aroclors Having relatively low chlorine content (a. g., 1221 and 1232). Although emission spectra of the more highly chlorinated PCB isomera are diffusa, the excitation spectra are usually more highly structured as compared with compounds of lo* chlorine content. Spectral characteristics of emission and excitation thua enable those Aroclors studied to ba distinguished. kons -<39- rif i. rifin ). bdtiHw/milMlN f 2. *. 1*. J* -iMrtrktor*klfMrl MCH |I*M 1100 ppM mt tV X hllftlM HMffWlOt T?*K iiKiMiM/mMiMWi.i.r.r-MnctttNM>inr) ! h*oM (ioo fiwi rr x HONS 04257? TO- ri|Wi . bcUMiMAmitliM of Ar*l*r liM In MCH lata (apprna. 0 ppm) at TT* K ttr* 7. Mbllur* of ppm p, f.OOT and f ppm Aroclnr I2M In MCH at IV K. Carta* A aai Bt Cacltatlon aptartra imrUwH ii )U iH 5 m. Cur*** C airi Pa (mUilH IfHIPI sl*0 at <40 an* 200 wn Plfin 4. iMlIilln/tmliilN # p. p-DOT in MCH fl|W MtoM # I ppm p, f -DPT and . ) ppm Ataclar 12*4 in MCH ai 77* R. Car** At Caettatlon appertain manttar*4 at )00 Mn. Curvoa 1 and Ca CmliaM *p*ctra awHat at 270 aai4 JH rnn. Cut** Di Eraltalaa a| alvtaat ncliH at 200 mm MONS 042578 71- Pesticides SmiMlen observed from DOE was found to b* at least 100 tim woakar than tha phosphor escence of comparable concentration* of DDD or DDT, suggesting that the weak emission which we observe may in fact be due to an impurity. Our results are not in agreement with those reported by Moye and Winefordner (13). Spectra of the four DDD and DDT compounds are very similar. As an example, the epectrum of p, p*-DDT in MCH is shown in Figure 6. Phosphorescence origins are in the region 355*365 nm. The band systems are slightly structured to the short wavelength side of the maximum but become stronger and more diffuee at longer wavelengths. Phosphor escence intensities are about ten time* weaker than for Aroclors. The exeitatlon spectra characteristically show prominent narrow (3-4 nm half-widths) in MCH at 275*278 nm. Our results are in reasonable agreement with those of Moye and Winefordner <13), and the excitation spectra resemble the absorption spectrum of the psrent hydrocarbon, diphenyl methane, as given by Berlman (14). Spectra of p, p'-DDT in heptane revealed no additional sharpening, in contrast to some of the PCB isomers dis cussed previously. Analysis of Mixtures; Aroclor 1254 and p.p*DDT Several mixture* of the above materials were studied at various relative concentrations of tbs components in order to assess the potential of the low temperature method. Excitation/ mission spectra of a mixture consisting of 50 ppm p.p'-DDT and 50 ppm Aroclor 1254 appear in Figure 7. Since DDT has relatively little absorption at wavelengths longer than 210 nm, excitation of the mixture at 290 nm excites the Aroclor phosphorescence with virtually no interference from DDT. In addition, by monitoring the 380 nm emission, where the Aroclor has practically no emission Intensity, the excitation spectrum of DDT is obtained with little interference from Aroclor. Figure 8 shows spectra obtained for a mixture consisting of 5 ppm p, p*-DDT and 0. 05 ppm Aroclor 1254. Selective excitation of tbo Aroclor phosphorescence permits the Aroclor to be identified in the pretence of 100X greater concentrations of DDT. Continued studies are in progress to establish analytical curves and detection limits for tbs components, requiring a better understanding of possible energy-transfer processes. (Is those mixtures studied, no evidence of significant energy transfer was observed.) Detection Sensitivities hour work. Interference from emitting solvent (MCH) impurities limited detection sensi tivities to approximately 1 ppm for DDT and DDD and approximately 0. 01 ppm for Aroclors. *lth suitable solvent purification, these sensitivities should be improved by two orders of tagnitude and work in thia direction Is in progress. Tbs very low emission yield of the DDE compounds makes these difficult to determine with asitivlty; however, DDE should produce little interference with PCB determination. SUMMARY temperature luminescence offere a simple, sensitive method for determination of DDTcompounds, PCB's and for DDT/PCB mixtures. As such, it should constitute a useful ^pendent analytical approach, and might also be employed as an adjunct to other methods as gat chromatography. For example, thia technique should in principle be applicable HONS 0*2579 -72- to the analysis of polychlorinated terphenyls(PCT'e) present la certain PCB preparation! At column temperatures convenient for gas chromatographic analysis of PCB1 a, the PCT* have much longer retention times, resulting in either very broad peaks or secondary interference (3}. Chlorinated terphenyla are expected to lumlneace at low temperature and have emiaaion displaced to longer wavelengtha from that of the biphenyle. Low tem* perature luminescence involving the selective excitation of PCT's in the pretence of PCB1 might thus avoid complications which ariee in gae chromatography. ACKNOW LEDGEMENT3 We gratefully acknowledge the eupport and direction of Mr. D, Ballinger of the CPA Analytical Water Control Laboratory, Cincinnati, Ohio. ] * Wa ara indebted to Dr. R. C. Webb of th Athena, Georgia EPA Laboratory, and Dr. 0. Hutaingcr of the National Research Council of Canada, Halifax, Nova Scotia, for getterouely providing samples of PCB isomers. We also thank Dr. E. S. Tucksr of tha Monsanto Company for providing additional Aroclor aamplas. ' ' This work waa supported by the Environmental Protactlon Agency, Contract No. 68-01 -00*; REFERENCES 1. D. B. Peakall and J. L. Linear, BioScienee 20, 958(1970). 2. C. G. Gustafson, Envir. Set. and Tech. 4, 814 (1970). 3. L. M. Reynolds, Residue Reviews 34, 27 (1971). 4. V. Zltko and P. M. K. Choi, Fiaherlse Research Board of Canada, Technical Report No. 272 (1971). 5. R. W. RUebrough, in Impingement of Man on fee Oceana. D. W. Hood, Editor, Wlley-Intersc'ieoce, New York, 1971, pp. 259-286. 6. T. W. Duka, J. L Lowe, and A. J. Wilson, Jr., Bull. Envir, Contain, and Toxicol. , 171 (1970). 7. R. G. Webb and A. C. McCall, " Uentitiee of Polychlorinated Biphenyl (PCB) Isomers in Aroclore," presented at 162nd National Meeting of the American Chemi cal Society, Washington, D. C., 13 September 1971. 8. D. Sissons and D. Welti, J. Chromatogr. 60, 15 (1971). 9. A. C. Tae and R. H. de Vos, Envir. Sci. and Tech. 5, 1213 (1971). 10. D. S. McClure, J. Chem. Phye. 17, 905 (1949). 11. S. P. McGlynn, T. Aauml, and M. Xinoshita, Molecular Spectroscopy of the Triplet State. Prentice-Hall, Englewood CUfls, N. J., 1969, pp. 270-275. 12. E. V. Shpolakii, Sov. Phye. Uep. 3, 372 (I960); 5, 522 (1962); .411 (1963). 13. H. A. Moye and J. D. Wlnefordner, J. Agr. Food Chem. 1_3, 516 (1965). 14. I. B. Berhnan, Handbook of Fluorescence of Aromatic Molecules. Academic Press. New York, 1971, p. 126. HONS 042580