Improved analysis of captan, tetrahydrophthalimide, captafol, folpet, phthalimide, and iprodione in fruits and vegetables by liquid chromatography tandem mass spectrometry

An improved liquid chromatography tandem mass spectrometry method is reported for the determination of residues of captan (+ tetrahydrophthalimide), captafol, folpet (+ phthalimide), and iprodione in fruits and vegetables. The optimized electrospray ionization parameters (high cone gas flow, and a low desolvation temperature) did not result in degradation of target compounds, rather they provided a significant advantage over the conventional GC-MS/MS methods, which lack sensitivity and repeatability. Strategies for minimizing losses in recovery of these compounds during sample preparation included cryogenic comminution, extraction with acidified ethyl acetate or acetonitrile, and dilution of the final extract with acidified water prior to LC-MS/MS analysis. The method performance complied with the SANTE/11813/2017 guidelines, with recoveries in the range of 70-120% at the LOQ of 0.01 mg/kg across the tested matrices at various pHs. The efficiency of the method was reflected in its precision (RSDs < 10%) for incurred residues.