[Development of an LC-MS/MS-Based Rapid and Simple Analytical Method for Six Fungicides]

In this study, we developed an LC-MS/MS-based rapid and simple analytical method for six fungicides; imazalil, o-phenylphenol, thiabendazole, fludioxonil, azoxystrobin and pyrimethanil, the latter three were newly approved for use after 2011. For expediting and simplification, we merged the extraction method with that of the pesticide analysis. For purification step, loading of 1 mL of sample extracts to 500 mg Oasis HLB column and elution with 8 mL of acetonitrile gave satisfactory results. The performance of the present method was confirmed for orange, grapefruit, and lemon samples fortified with the six fungicides. The results showed that the average recovery ranged from 89.7 to 100.0%, intra- and inter-assay CV% ranged from 1.5 to 5.0% and from 0.5 to 4.9%, respectively, achieving the target values of the Japanese official guideline for residual pesticide analysis. The limits of quantification of this method were determined to be 1 mg/kg for o-phenylphenol, and 0.2 mg/kg for the other five fungicides. These values were lower than their corresponding regulation values. In addition, we confirmed the usability of the present method for fungicide inspection of commercially available citrus fruits. During 2017-2019, there was no conflict between the food labeling and the fungicides detected and no fungicide with the concentration exceeding maximum residue level was detected.