[Determination of alachlor residue in agricultural products]

A method of the determination of alachlor residue in agricultural products was developed. Four different kinds of objects, corn, peanut, spinach, and orange were selected as representatives of main agricultural products. The sample was extracted with acetone-water (8:2, v/v). The extract was partitioned with dichloromethane, cleaned up by gel permeation chromatography (GPC) and solid phase extraction (SPE) in order to completely separate colorants from alachlor in the sample. The eluate was evaporated under vacuum to nearly dry and diluted with acetone to a definite volume. The solution was determined and identified by gas chromatography-mass spectrometry (GC-MS) using external standard method. The recoveries were 86.0%-98.2%, and relative standard deviations were 5.1%-6.7% with spiked at 0.010-0.200 mg/kg of alachlor in blank samples. The limit of quantification of this method was 0.010 mg/kg.