DETERMINATION OF OXAMYL AND METHOMYL BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY USING A SINGLE-STAGE POSTCOLUMN DERIVATIZATION REACTION AND FLUORESCENCE DETECTION

A method is described for the determination of oxamyl and methomyl residues in apples, oranges, soybean leaves, insects, and river water by high-performance liquid chromatography. This method uses matrix solid-phase dispersion isolation, a single-stage postcolumn derivatization reaction, and fluorescence determination. Recovery data for both oxamyl and methomyl were obtained by fortifying the raw agricultural commodities (RACs) at levels ranging from 20 to 1000 ng/mg and the water at levels ranging from 5 to 50 ng/mL. The recoveries ranged from 72 to 129%. The limits of detection, calculated as 4 times the baseline noise, were 5 mg/mL for water and 20 ng/g for the RACs tested.