Determination of imidacloprid, metalaxyl, myclobutanil, propham, and thiabendazole in fruits and vegetables by liquid chromatography–atmospheric pressure chemical ionization–mass spectrometry
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Imidacloprid, metalaxyl, myclobutanil, propham, and thiabendazole have been simultaneously determined in strawberries, oranges, potatoes, pears, and melons by matrix solid-phase dispersion (MSPD) followed by liquid chromatography–atmospheric pressure chemical ionization–mass spectrometry (LC–APCI–MS) in positive-ion mode. The samples were homogenized with C8 bonded silica as MSPD sorbent, placed in a glass column, and eluted with dichloromethane. Chromatographic separation of the compounds was achieved on a reversed-phase LC column using a methanol–ammonium formate (50 mmol L–1) gradient as a mobile phase. Samples were screened by monitoring the protonated molecular ion at m/z 256 for imidacloprid, 280 for metalaxyl, 289 for myclobutanil, and 202 for thiabendazole, and the main fragment at m/z 138 for propham. Positive samples were confirmed by multiple-ion monitoring. The repeatability (<20%) and recovery (>57%) of the method were good, and limits of detection (<0.05 mg kg–1) were adequate.
KeywordsMelon Imidacloprid Ammonium Formate Metalaxyl Thiabendazole
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