A single residue method for the determination of chlorpropham in representative crops using high performance liquid chromatography

A single residue analytical method was developed for herbicide chlorpropham in various crops. Brown rice, apple, mandarin, Kimchi cabbage, green pepper, potato, and soybean were selected as representative crops, and clean-up system, partition solvent, and extraction solvent were optimized. For high performance liquid chromatography (HPLC), C₁₈ column was used with elution solvents of water and acetonitrile. Limit of quantitation (LOQ) of chlorpropham was 2 ng (S/N >20), and excellent linearity (R²=1. 000) was achieved. Method limit of quantitation (MLOQ) was 0. 02 mg/kg. For recovery tests, crop samples were macerated and fortified with chlorpropham standard solution at three fortification levels (MLOQ, 10 MLOQ, and 100 MLOQ). And then those were extracted with acetonitrile, concentrated and partitioned with n-hexane. The n-hexane layer was then concentrated, cleaned-up through Florisil® column with ethyl acetate:n-hexane (5:95, v/v) prior to concentration and analysis with HPLC. Good recoveries from 76. 8 to 107. 9% with coefficients of variation of less than 10% were obtained, regardless of sample type, which satisfies the criteria of Korea Food and Drug Administration. Those results were confirmed with liquid chromatography-mass spectrometry (LC-MS). The method established in this study could be applied to most of crops as an official and general method for the analysis of chlorpropham residue.