Thin -layer Chromatographic Separation and Identification of Carbofuran and Two Carbamate Metabolites and their Dinitrophenyl Ethers

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Abstract
Residues of carbofuran and its 2 carbamate metabolites in fortified fresh water, a sandy loam soil, and plant tissues were extracted with HCl, partitioned into methylene chloride and cleaned up on deactivated Florisil. Aliquots of extracts were chromato-graphed on silica gel G and GF plates and carbofuran, 3-hydroxycarbofuran, and 3-ketocarbofuran were hydrolysed into their 7-phenols with KOH spray. Spots were visualized with either p-nitrobenzenediazonium fluoroborate or 2,6-dibromobenzo-quinone-4-chloroimine. The characteristic color of spots before and after spraying with KOH or with either of the chromogenic reagents in ordinary light and under UV light helped in identification and differentiation of the compounds. As low as 0.05ppm in water and 0.2ppm in soil or strawberry, lettuce, carrots, peas and potatoes could be detected. 3-Hydroxycarbofuran in the remaining extracts was converted into 3-ethoxycarbofuran and the compounds were converted into their dinitrophenols and chromatographed on silica gel GF. Good separation of compounds was obtained but the limit of detection was 0.1 ppm in water and 0.3 ppm in soil and plant tissues. The procedures were applicable to field-treated rutabaga samples and useful in identity confirmation.

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