Analytical method for residues of propineb and propylenethiourea in agricultural products

A method was developed for the determination of propineb and propylenethiourea in agricultural products. Propineb was measured as propylenediamine after hydrolysis with acidic stannous chloride. The propylenediamine was reacted with 1-dimethylaminonaph-thalene-5-sulfonyl chloride, and after standing for 3 hours, the product was separated by thin-layer chromatography and quantitated by dual-wavelength densitometry. Propylenethiourea was quantitated by FPD-GC of its N-methanesulfonylated S-(m-trifluoromethyl-benzyl) derivative. The recoveries of propineb added to crops were in the range of 41 to 74%. Those of Propylenethiourea added to crops were in the range of 77 to 107%. In the analysis of commercial products, propylenethiourea was detected in 50% of beer samples in the range of 0.001 to 0.007ppm.