Establishment of analytical method for cyazofamid residue in apple, mandarin, Korean cabbage, green pepper, potato and soybean

Abstract

A precise single residue analytical method was developed for fungicide cyazofamid in various crops. Apple, mandarin, Korean cabbage, green pepper, potato, and soybean were selected as representative crops, and clean-up system, partition solvent and extraction solvent were optimized. Limit of quantitation (LOQ) of cyazofamid was 2 ng (S/N>10) and good reproducibility was observed with small coefficient of variation (<4%). Excellent linearity was achieved between 0.05 and 20 mg/ kg of cyazofamid standard solutions, with coefficients of determination of 1.000. Method limit of quantitation (MLOQ) was 0.02 mg/kg. For recoveries tests, crop samples were macerated and fortified with cyazofamid standard solution at three fortification levels (MLOQ, 10 MLOQ, and 100 MLOQ). And then those were extracted with acetone, concentrated and partitioned with dichloromethane. Then the extracts were concentrated again and cleaned-up through Florisil® column with ethyl acetate: n-hexane (30:70, v/v) before concentration and analysis with HPLC. Good recoveries from 75.3 to 98.5% with coefficients of variation of less than 10% were obtained, regardless of sample type, which satisfies the criteria of KFDA. Those results were reconfirmed with LC-MS/MS. The method established in this study could be applied to most of crops as an official and general method for residue analysis of cyazofamid.