DEVELOPMENT OF AN ANALYTICAL PROCEDURE FOR AN INSECT GROWTH-REGULATOR (EL-494) EMPLOYING HIGH-PRESSURE LIQUID-CHROMATOGRAPHY AND ITS APPLICATION ON RESIDUES IN ALFALFA

A prodcedure was developed for the analysis of an insect growth regulator (EL-494) employing high-pressure liquid chromatography (LC). The plant tissue was washed and extracted with acetone. The extract was concentrated and cleaned up using a Florisil column. The concentrated eluate was analyzed by LC employing a .mu.Bondapak C18 column and a methanol-water solvent system. EL-494 was detected by UV adsorption and the lower limit of detection was 10 ng. For demonstration of the practical application of this procedure, samples of alfalfa field treated with a 50% wettable powder formulation of EL-494 at 3 concentrations (283.5, 567.0 and 1134.0 g of AI[active ingredient]/ha), were analyzed for 9 wk. Recoveries of spiked samples varied from 94.9-96.2% EL-494 (from 50-5000 ng) with a lower limit of detection of 0.025 ppm.