CHARACTERISTICS OF AN EXTRACTION AND PURIFICATION PROCEDURE FOR CHLORINATED DIBENZO-PARA-DIOXINS AND DIBENZOFURANS IN SOIL AND LIVER

Liver is extracted with chloroform-methanol to give essentially quantitative tranfer of endogenous chlorinated dibenzo-p-dioxins (CDD) and dibenzofurans (CDF) into the organic phase. A new procedure involving LH-20 Sephadex is used to remove most of the lipids from the extract. Soil is extracted by a simple, rapid and economical procedure giving very high recoveries of CDD and CDF from sandy soil, various types of clay and humus-rich loam. Subsequent cleanup on basic and acidic alumina complete the preparation for gas chromatography-mass spectrometric analysis. The use of propylene glycol as a "keeper" and of 2,3,7-trichlorodibenzo-p-dioxin as a carrier minimizes losses during evaporation of solvents and on glass surfaces. Interactions of 2,3,7,8-CDD with organic material in loam slightly reduce recovery but there is no indication of high affinity binding sites, the losses being apparently associated with simple distribution coefficients. Special precautions needed to avoid losses of CDF on alumina chromatography are described, and the effect of "aging" spiked soil is discussed.