No abstract

Capillary gas chromatography-electron impact mass spectrometry is used to confirm the presence of levamisole in cattle and swine livers at the 0.1 ppm tolerance level. Use of a fused silica capillary column from injector to detector solved chromatographic problems encountered with the analyte. Of the mass specrrometric techniques evaluated, electron impact mass spectrometry provided the most satisfactory data for a confirmatory method. Recoveries from swine and cattle livers fortified at 0.1 ppm averaged 74.9 and 72.7%, respectively, indicating potential utility of this methodology as a quantitative method. Apparent levamisole residues in control livers were less than 0.01 ppm

A colorimetric procedure has been devised to determine residues of the dithiolane insecticides, 2-diethoxyphos-phinothioylimino-1,3-dithiolane (I) and 2-diethoxyphosphinylimino-1,3-dithiolane (II), in cottonseed and on cotton foliage. The chromogenic reaction is based on the acid hydrolysis of the dithiolane insecticides to 2-imino-1,3-dithiolane, which is converted by treatment with alkali to thiocyanate. The thiocyanate is converted to cyanogen bromide and then reacted with benzidine-in-pyridine solution to form an intense red solution with absorbance maximum at 530 mμ. Recoveries of I and 11 from cottonseed averaged 83 ± 5% and 68 ± 4% in the range 0.1-1 ppm, with background values of 0.04 ± 0.01 ppm; recoveries from cotton foliage averaged 79 ± 7% and 84 ± 7%, respectively, for I and II, with background values of 0.02 ± 0.01 ppm.

A gas chromatographic/mass spectrometric method capable of confirming phorate, terbufos, their sulfoxides, and sulfones in water is reported. Parents and their metabolites are separated in less than 5 min using a short capillary GC column and high carrier gas linear velocities. Positive ion chemical ionization mass spectrometry generates (M + H) ions indicative of the different molecular weights of the analytes and at least one confirmatory fragment ion for each analyte. Residues have been qualitatively confirmed at the 1 ppb level in fortified water samples from a variety of sources. Apparent residues in control water were less than 0.1 ppb.