Liquid chromatographic-mass spectrometric determination of postharvest fungicides in citrus fruits

Liquid chromatography (LC)-atmospheric pressure ionisation (API)-mass spect rometry (MS) has been used to determine residues of five fungicides in oran ges with a minimum sample cleanup. Atmospheric pressure chemical ionisation (APCI) and electrospray (ES) were compared and both gave similar results i n terms of sensitivity and structural information. The main ions were [M+W] (+) for carbendazim, imazalil, thiophanate methyl and thiabendazole, and [M +H-C4H9NHCO](+) for benomyl. Samples were extracted with sodium sulphate an d ethyl acetate. Although benomyl and thiophanate methyl were transformed t hrough the extraction procedure to carbendazim, the method showed good prec ision (<13%) and recovery (>70%), except for thiophanate methyl (50%). whil st also yielding limits of detection (<0.03 mg kg(-1)) that are adequate fo r the determination of the studied fungicides in oranges. <(c)> 2001 Elsevi er Science BN. All rights reserved.