Establishment of Residue Analysis of Propanil (Dichloropropionanilide), Linuron and Diphenamide in Agricultural Commodities

A method for simultaneous determination of residues of three herbicides containing nitrogen, propanil (3′,4′-dichloropropionanilide), linuron and diphenamide, in agricultural commodites was established. The herbicides were extracted by acetone from samples, transferred into dichloromethane, then the dichloromethane extract was dried. The residue was dissolved in n-hexane, and purified from oily contaminants by partition with acetonitrile. The acetonitrile extract was further purified by Florisil column chromatography with dichloromethane. Diphenamide was determined directly by use of gas chromatograph equipped with a flame-thermoionic detection system (FTDGC). DCPA and linuron were derivatized into their N-monomethyl derivatives by a strong methylation method by use of sodium hydride and methyl iodide in a mixture of dimethyl sulfoxide and benzene, and then subjected to determination by FTD-GC. Recoveries of the three herbicides from brown rice, barley, corn, potato, carrot and onion were not less than 80% at the additional level of 1.0 ppm, while not less than 70% at 0.1 ppm level, respectively.