Spectrophotometric determination of carbaryl in grains.

A method for detn. of residues of the insecticide carbaryl [1-naphthyl N-methyl carbamate] in cereals and pulses is described. It is based on hydrolysis of carbaryl with methanolic KOH to give 1-naphthol, which is then reacted with 4-aminophenazone in the presence of K3Fe(CN)6 under alkaline conditions to give a reaction product which is determined by spectrophotometry at 475 nm. Absorbance is linearly related to concn. over the range 0.5-20 mug/ml. Recovery studies were conducted on rice, wheat, sorghum, pigeon peas, black gram and green gram; % recovery ranged from 94.0 to 100.0. Detection limit is 0.3 p.p.m.