DETERMINATION OF CARBOFURAN AND ITS CARBAMATE METABOLITE RESIDUES IN CORN USING A NITROGEN-SPECIFIC GAS CHROMATOGRAPHIC DETECTOR

A gas chromatographic method capable of determining carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) and 3-hydroxycarbofuran (2,3-dihydro-3-hydroxy-2,2-dimethyl-7-benzofuranyl methylcarbamate) residues in field corn is presented. The intact methylcarbamate residues were determined using a nitrogen-specific microcoulometric detection system. An acid hydrolysis converted the water-soluble conjugated residue forms to the organoextractable aglycone forms. Corn stover and corn cob samples required a silica gel-Nuchar-Attaclay column cleanup. Corn kernel samples required both an acetonitrilehexane partition to remove oil and a silica gel-Nuchar-Attaclay column cleanup. Average recoveries were 70% for carbofuran ard 3-hydroxvcarbofuran for the various corn samples at fortification levels from 0.05 to 0.9 p.p.m. © 1969, American Chemical Society. All rights reserved.