Abstract: Enzyme screening method was simple and rapid to determine the pesticide residues based on the butyryl cholinesterase activity inhibition by both organic phosphorous and carbamate pesticide residue in the sample. Nevertheless false positive results in leek samples were reported because of the assay interferences with leek. In this study the heat treatment was applied to eliminate the false positive results of pesticide residue in leek, so the sample preparation procedure was improved and the results showed that the test sample heating treatment can temperature and time decrease the false positive result.

Key words: enzyme screening method, false positive results, leek