Analyses of pesticide residues in fruit-based baby food by liquid chromatography/electrospray ionization time-of-flight mass spectrometry

A liquid chromatography/electrospray ionization time-of-flight mass spectrometry (LC/ESI-TOFMS) method has been developed for the determination of 12 pesticides (namely, carbendazim, thiabendazole,imazalil, tridemorph, triadimefon, bitertanol, prochloraz, flutriafol, myclobutanil, iprodione, diphenylamine and procymidone) in fruit-based baby food (multi-fruit jars and juices intended for infant consumption). The developed method consists of a sample treatment step based on liquid-liquid extraction using acetonitrile, followed by a clean-up step based on dispersive solid-phase extraction (SPE) with a primary-secondary amine (PSA). Multi-fruit and apple juices were processed by a SPE procedure using Oasis HLB(TM) cartridges. Subsequent identification and quantitation was accomplished by LC/ESI-TOFMS analysis: the confirmation of the target pesticides was based on accurate mass measurements of selected ions (protonated molecules ([M+H](+)) and fragment ions). Confirmation studies were accomplished at low concentration levels (10 mu g kg(-1)) and accuracy errors lower than 2 ppm were obtained in most cases. Baby food extracts spiked at 10 mu g kg(-1) fortification level yielded average recoveries in the range 78-105% with relative standard deviations less than 10% for most of the analytes. Limits of detection (LODs) were between 0.1 and 4 mu g kg(-1) depending on the pesticide studied. Finally, the proposed method was applied to a total of 33 baby food samples from Spain and the United Kingdom. Although imazalil, thiabendazole and carbendazim were detected in a high number-over 60%-of baby food samples, none of the samples tested were found to be above the 0.01 mg kg(-1) EU standard. Copyright (C) 2007 John Wiley & Sons, Ltd.