Liquid chromatographic determination of azinphos methyl oxon in foliar dislodgeable residues and in soil surface dusts from an azinphos methyl-treated orange grove.

Specific parts of the worker environment in an orange grove that had been sprayed with azinphos methyl formulation were tested for azinphos methyl oxon. Extracts of soil surface dusts and dislodgeable residues from orange leaf surfaces were prepared and analyzed by liquid chromatographic procedures incorporating an ultraviolet absorption detector primarily for quantitation and an on-stream chemical reaction detector primarily for confirmation. Azinphos methyl oxon residues were found in both types of samples collected 3-59 days after spraying. Foliar dislodgeable residues of the oxon ranged from a high of 0.057 microgram/sq cm of leaf surface on the 17th day to a low of 0.014 microgram/sq cm on the 59th day for trees treated with a low-volume spray. The corresponding range in soil dust samples was 5.2 microgram/g (ppm) of dust on the 10th day to 1.4 microgram/g on the 59th day. Values were 9.7 and 2.7 microgram/g, respectively, for samples from under trees similarly treated with a high-volume spray.