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

Residue methodology is described for the determination of AC 217,300 residues in pasture grass and crop samples. After extraction and subsequent cleanup on an XAD-2 column, residues of AC 217,300 are determined by liquid chromatography (LC), using a reverse phase paired-ion chromatographic system and detection at 300 nm. The method has a validated limit of sensitivity of 0.05 ppm with corresponding control values for the commodities analyzed of <0.01 ppm. Apparent residues over 0.05 ppm can be confirmed by either gas chromatography with an electron capture detector (GC-EC) or gas chromatographynegative ion chemical ionization mass spectrometry (GC-NICI). The direct GC-NICI method circumvents the need for sample cleanup on the XAD-2 column, and offers a greatly simplified procedure that is useful for screening samples. Recoveries of AC 217,300 from the commodities analyzed have been satisfactory with all methods of analysis

A gas chromatographic method for the determination of residues of famphur, 0,p-(dimethylsulfamoy])phenyl 0,0-dimethyl phosphorothioate, an organophosphate systemic insecticide, and its oxygen analog is described. Famphur and its oxygen analog are separated from each other by column chromatography. The two compounds are then hydrolyzed in alkaline medium to p-hydroxy-7V,A-dimethylbenzenesulfonamide, which then reacts with hexamethyldisilazane.The resultant trimethylsilylether derivative is measured by gas chromatography. This method is satisfactory for the detection of famphur and oxygen analog residues in calf muscle, liver, and kidney down to levels of 0.05 p.p.m. and in milk to 0.005 p.p.m.