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( I O ) Albery. W. J.; Baftlett, P. N.; Craston, D. H. J . Electraenel. Chem. 1985, 194, 223. (11) (a) McKenna, K.; bajter-Toth, A. Anal. Cbem. 1987. 59, 954. (b) Hell, P. D.; Wlghtman, R. M. Mol. Ctyst. Llq. Cryst. 1988, 160, 269. (c) Hell, P. D.; Skothelm, T. A. Synlh.Met. 1968, 28, C853. (12) Davldson, V. L. Am. Lab. 1990. Feb, 32. (13) D'coste, E. J.; Higglns, 1. J.; Turner, A. P. F. Bbsensors 1986, 2 , 71. (14) Dulne, J. A.; Jongejan, J. A. Ann. Rev. Blochem. 1989. 58, 403. (15) Gunedngham, H.; Tan, C.H. Anel. Chlm. Acta 1990, 229, 83. (18) Anthony, C.; Zatman, L. J. Bkchem. J. 1964, 92, 614. (17) bidberg, I. EW. J . Blochem. 1976, 63, 233. (18) "forth. C. W.; Quayie, J. R. Bbchem. J . 1978, 169, 677. (19) h i n e , J. A.; Frank, J.; Westerling, J. BlocMm. Bkphvs. Acta 1978, 524, 277. (20) Duine, J. A.; Frank, J. Bkchem. J. 1980, 187, 213.
(21) Anthony, C. A&. Mlcrobiol. my&/. 1986, 27, 113. (22) Anthony, C.; Zatman. L. J. Bkhem. J . 1985. 98, 808. (23) Albery. W. J.; Bartlett, P. N.; Cass, A. E. 0. f i l l . Tr8ns. R . Soc. London. B 1987, 8318, 107. (24) Kulys, J. J. Biossnsors 1988, 2 , 3. (25) Hill, 6.S.; Scolarl, C. A.; Wilson, G. S. J . Electmenel. Chem. 1988, 252, 125.
RECEIVED for review October 29, 1990. Accepted February 25, 1991. We thank NSERC (Canada) and the McGill Graduate Faculty for providing financial support of this research.
CORRESPONDENCE Silver Complex of Poly(methylphenylsi1oxane) as the Active Component for Separation of Aliphatic, Olefinic, and Aromatic Hydrocarbons by Gas Chromatography Sir: Poly(ethy1ene glycol) solutions of AgN03 have been widely used in gas chromatography to separate unsaturated and saturated hydrocarbons since silver ion reacts very fast with the former, forming weak D complexes (1,2). However, the chromatography must be performed at a temperature as low as 50 OC since poly(ethy1ene glycol) reduces Ag+ to A$ at higher temperatures. We have found that OV-17, poly(methylphenylsiloxane), dissolves AgCF3C02and AgCF3S03,indicating coordination of the phenyl group to Ag+. The resulting solution is stable at 150 OC for several weeks and at 170 OC for several days when kept in the dark. We failed to observe direct evidence of a silver-0V-17 complex by conventional methods such as isolation of the complex, IR,W, or 'H or '3c NMR spectroscopy. Vacuum vapor pressure osmometry ( 3 , 4 ) was used to determine the molecular weight of OV-17 (Supelco,Inc., Supelco Park, Bellfonte, PA). A CHC13 solution, 1.00 m based on monomer unit, was found to be 0.102 m,which indicates that the average number of polymerizations of the siloxane monomer was 9.8; hence, the molecular weight approximatea 1330. Silver trifluoroacetate was dissolved in the same solution to 0.053 m, and the resulting solution was found to be 0.102 m. Since the dinsolved AgCF3C02did not increasethe number of solute molecules, all Ag+-containing species had to be bonded to OV-17 as shown in eq 1. AgCF3C02 + OV-17 = AgCF3C02-OV-17 (1) It should be mentioned that CHC13 does not dissolve AgCF3C02if OV-17 is absent. Silylatsd diatomaciousearth, 2.64 g, was added to a solution of AgCF3C02(0.313 g) dissolved in 10 mL of benzene containing 0.387 g of OV-17,and the solvent was evaporated on a water bath. The residual solid was packed in a stainless steel column for gas chromatography, 1/8-in.0.d. X 6-ft length. It was found that a mixture of cyclohexane, cyclohexene, and benzene was separated poorly by use of OV-17 supported on silylated diatomaceus earth at 150 "C. However, the silverbearing column separated the mixture, as shown in Figure 1, over a wide range of temperature, 60-150 "C. As seen in Figure 1,the saturated hydrocarbon C8H12remained at a similar retention time in a column of either OV-17 or OV-17 with dissolved AgCF3C02. Benzene and CeHloattained higher retention times in the silver-bearing column. The slight reduction of the retention for C8Hloin the latter column might be caused by a salting-out effect as shown by Muchs and Weiss (5). 0003-2700/81/0363-1178$02.50/0
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naUn 1. Chrometogram of CdHI2 (I), C,H, (2), and CdH,, (3) by (a) OV-17 and (b) OV-17 with AgCF,CO, at 77 O C . It has been observed that the silver-bearingcolumn separates unsaturated hydrocarbons from the saturated ones as a column composed of AgNO, dissolved in ethylene glycol (5). LITERATURE CITED (1) Branford, B. W.; Harvey, D.; Chalkby, D. E. J . Inst. Pet. 1955. 4 1 , 80. (2) Tenney, H. M. Anal. Uwm. 19S8, 30, 3. (3) a u r a , T.; Casllles, R. Anel. Chem. 1980, 52. 1373. (4) Yanlglhara, N.; Sampedro, J. A.; Casllles, R.; Fernando, Q.; Ogura, T. "WQ. a m . 1982, 21, 475. (5) Muchs, M. A.; W e b , F. T. J. Am. Chem. Soc. 1962, 84. 4697.
' O n leave from the Departmenl of chemistry, Unlverslded Aut-
Metropolha, Apdo. 55-534, Mexlco D.F.
Depaftmnt of Material Science and Engineering, School of Sclence and Enginwing, Telkyo Unhrerslty, Utsunomlya, Tochlgl, Japan.
*Rmt adbw:
Ana Maria Sotol Naohisa Yanagihara* Tetsuya Ogura* Department of Chemistry Universidad Autonoma de Guadalajara Apdo. 1-440 Guadalajara, Jal., Mexico
RECEIVEDfor review October 8,1990. Accepted February 21, 1991. The residence of A.M.S. was supported by CONACYT and the Universidad Autonoma Metropolitana in order to fulfill the requirement of the graduate program. Ca 1991 American Chemical Society
