Gas Chromatographic Analysis of the Fate of N-methyl-2-3-substituted Phenylcarbamate in the Dairy Cow

Abstract

Mobile Chemical''s carbamate insecticide, MC-A-600 (N-methyl-2-3-substituted phenylcarbamate) shows promise for forage insect control. The compound was fed at a feed level of 100 ppm for 4 days to a catheterized Holstein cow and milk and urine samples were analyzed by electron affinity gas chromatography to determine its fate. The method involved acetone extraction, isolation using selective extraction into chloroform and aceto-nitrile, and hydrolysis, bromination, and acetylation of the compound to yield the 4,6-brominated phenyl acetate derivative. This product was very sensitive (0.1 ppm) to electron affinity determination. No residues of the insecticide were found in the milk. A large peak was consistently identified in the urine as presumably the glucuronide or ethereal sulfate of MC-A-600 phenol. A second peak found in the urine chromatograms could not be identified.