Abstract
Gas chromatographic determination was modified for 1, 1-bis-(p-chlorophenyl) ethanol (chlorfenethol), p, p'-dichlorobenzilic acid ethyl ester (chlorobenzilate) and p, p'-dichlorobenzilic acid isopropyl ester (chloropropylate) and its applicability to forensic chemistry was tested. All of these acaricides have tertiary hydroxy group, which is quickly and quantitatively esterified with trifluoroacetic anhydride (TFAA). In the gas chromatographic system with the column packed with 2% SE-30 on Celite 545 AW-DMCS, the retention time of the esters was shortened, and the peaks were more symmetric than those of the parent substances. Adequate amounts for the complete esterification of 5 mg of the acaricides were 20 to 50μl of TFAA and 10 to 500μl 111 of pyridine, and tetrahydrofuran was suitable as a reaction solvent. Anthracene was used as an internal standard, and its calibration curve showed a good linearlity in the range of weight ratio 0.22. Coefficient of variance were 3% in chlorfenethol, 3.5% in chlorobenzilate and 3.2% in chloropropylate. Miso-soup, milk, fermented milk and triturated liver, containing 50 ppm of acaricide, were prepared and after the addition of anhydrous Na2SO4, acaricides were extracted with acetone. Acetone was evaporated and the residual liquid were again extracted with hexane. The extracts were separated from other impurities by hexane-acetonitrile distribution and thin-layer chromatography. Recoveries were (6073)% for chlorfenethol, (7178) % for chlorobenzilate and (7380)% for chloropropylate.
