Several carbamate insecticides that are insentitive to electron affinity G.L.C. analysis were hydrolyzed and brominated to yield derivatives that were several thousand times as sensitive to this method of detection. A field experiment was conducted in which Sevin (1-naphthyl-n-carbamate) was applied to snap beans, extracted with methylene chloride, and analyzed by electron affinity gas chromatography following hydrolysis and bromination. Crop samples, spot-checked by a colorimetric procedure, resulted in comparable residue data. A rapid, qualitative screening procedure for the detection of Sevin and other similar carbamates at plant residue concentration of 2 ppm or higher was developed.