A confirmatory analytical method for post-harvest fungicides in perishable vegetables and fruits using liquid chromatography tandem mass spectrometry

In this study, we developed a simultaneous analysis method for eight post-harvest fungicides commonly used on imported fruits and vegetables using high-performance liquid chromatography with tandem mass spectrometry (LC-MS/MS). The tested fungicides included azoxystrobin, imazalil, propiconazole, pyrimethanil, thiabendazole, difenoconazole, ortho-phenylphenol and fludioxonil. The proposed method employed specialised solid-phase extraction (SPE) columns tailored for these fungicides, streamlining sample preparation and improving our previously developed multi-residue pesticide and preservative analysis techniques. During analysis, samples were extracted with 20 mL of acetonitrile using a ceramic homogeniser. The extract solutions were then purified using two SPE columns before LC-MS/MS analysis. The method demonstrated good linearity, with limits of quantification of 10 µg/kg. During validation, recoveries for the eight fungicides ranged from 73.2% to 105.3%, with relative standard deviation of repeatability values between 0.9% and 17.2% and within-laboratory reproducibility values between 1.9% and 24.7%. Thus, this method meets the Japanese validation guideline criteria, indicating high reproducibility. This method is superior to existing approaches. It reliably analyses a wide range of vegetables and fruits, with a quantification limit of 10 µg/kg. This method can be fully utilised for routine monitoring of fungicides in food safety management.