DETERMINATION OF ACCOTHION ITS OXYGEN ANALOG AND ITS CRESOL IN CORN GRASS AND MILK BY GAS CHROMATOGRAPHY

Residues of Accothion (O,O-dimethyl O-4-nitro-m-tolyl phosphorothioate), its oxygen analog, and its cresol hydrolysis product were determined in corn plants, coastal Bermuda grass, and milk. The compounds in the extract were separated by liquid chromatography on silica gel containing 20% water; a solvent partition was applied to one milk fraction and an alumina column cleanup to one fraction from the corn or grass. The Accothion and oxygen analog fractions were analyzed by gas chromatography with a flame-photometric detector sensitive to phosphorus and the cresol fractions by gas chromatography with a Ni63 electron-capture detector. Recoveries of Accothion were 94 to 100%; those of its oxygen analog were 90 to 96% from corn and grass and 80 to 82% from milk; those of the cresol were 90 to 97%. The sensitivity of the method was 0.001 to 0.002 p.p.m. for Accothion and its oxygen analog and about 0.01 to 0.02 p.p.m. for the cresol. © 1969, American Chemical Society. All rights reserved.