Separation and Determination of Polychlorinated Biphenyls and DDE by Oxidation in Solid Support

Abstract

In order to be able to carry out an easy separation of 1, 1-dichloro-2, 2-bis (p-chloro-phenyl) ethylen (DDE) and polychlorinated biphenyls (PCB's), a convenient and rapid procedure for the oxidative derivation of DDE to p, p'-dichlorobenzophenone (DCBP) was developed. An aliquot of cleaned-up sample was applied on a microcolumn filled with zones of silica gel/water and silica gel/chromium trioxide/50% acetic acid as a solid support. The microcolumn was then heated in an oven at 100° for 2hr. In the subsequent fractionation by dry column chromatography, PCB's were eluted in the hexane fraction, while DCBP produced by oxidation was eluted in the ethyl etherhexane (15 : 85) fraction. These eluates were applicable to electron-capture gas chromatographic analysis without any further manipulation. The yield of DCBP from DDE in the 0.1-3μg range was practically quantitative, and the recovery of PCB's in the 0.5-3 μg range was 74 to 99% according to the average chlorine content of the individual PCB preparations.