RESIDUES AND TRACE ELEMENTS Evaluation of a Method Based on Liquid Chromatography/ Electrospray Tandem Mass Spectrometry for Analyzing Eight Triazolic and Pyrimidine Fungicides in Extracts of Processed Fruits and Vegetables ANNA SANNINO Stazione Sperimentale per l’Industria delle Conserve Alimentari, Viale F. Tanara 31/A43100 Parma, Italy The feasibility of using liquid chromatography/ electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) for determining 8 fungicides (triadimenol, penconazole, propiconazole, hexaconazole, cyproconazole, myclobutanil, fenarimol, and bitertanol) in extracts of tomato puree and lemon juice concentrate has been evaluated. A miniaturized extraction–partition procedure requiring small amounts of nonchlorinated solvents has been used. The extracts (5 mL) were analyzed by LC/ESI-MS/MS without any previous cleanup step. Chromatographic determination has been performed using a C18 column and isocratic elution. Seventeen MS/MS transitions of precursor ions were monitored simultaneously (2 or 3 for each pesticide). The excellent selectivity and good linearity of the LC/MS/MS method allowed quantitation and identification at low levels (limits of quantitation <0.010 mg/kg), even in difficult matrixes, with a run time of only 1.5 min. U se of agrochemicals in pre- and post-harvest control of fungal diseases in fruits and vegetables play an important role in food protection and quality preservation. Several triazolic and pyrimidine derivatives are systemic fungicides used to control a wide range of fungal pathogens on field crops, fruits, and vegetables. Active ingredients inhibit cell membrane ergosterol biosynthesis and stop development of the fungi (1). Due to their toxic properties, the presence of residues in fruits and vegetables can be a significant cause of human exposure. Maximum residue limits have been set by Italian government agencies and the European Union (2, 3). Methods of individual and simultaneous determination of triazol and pyrimidine residues in foods were described in the literature (4–10). The most frequently used methods rely on gas chromatography (GC) separation (4–8) and detection with selective and sensitive detectors such as electron capture (ECD) and nitrogen-phosphorus (NPD). GC with mass spectrometry (MS) in selective ion monitoring (SIM) or in full scan modes has also been used as either a confirmation or quantitation method (4–7). GC/tandem MS (GC/MS/MS) was also used to determine propiconazole, triadimenol, and myclobutanil in fruits, vegetables, and milk (8). However, azole compounds are difficult to sensitively determine by GC because their analysis is accompanied by peak tailing and relatively low response. Methods based on liquid chromatography (LC) coupled with ultraviolet (UV) or fluorescence detection have been developed for the determination of some triazol fungicides in fruits (9, 10). Bicchi et al. (10) determined 6 triazolic pesticides in apple and pear pulps by LC with UV diode array detection. Limits of quantitation (LOQs) below 10 ppb were obtained, but the method involved a complex cleanup procedure in order to remove matrix interferences. LC in combination with MS is becoming one of the most powerful techniques for the analysis of pesticides in complex samples (11). Modern LC/MS instruments employing atmospheric pressure ionization (API) provide excellent sensitivity and selectivity that enable analysis of target analytes at trace levels. Recently, several applications have involved the use of MS/MS with direct injection of vegetable extracts and without any cleanup step. These methods included the determination of triazol and pyrimidin fungicides at concentrations below 10 ppb (12–14). In this paper, the possibility of analyzing extracts from processed fruits and vegetables using a triple-quadrupole instrument with an electropray ionization (ESI) interface and no sample pretreatment except for an extraction–partition step was evaluated. The aim was the rapid residue determination of 8 fungicides (triadimenol, penconazole, hexaconazole, mychlobutanil, cyproconazole, propiconazole, fenarimol, and bitertanol) in tomato puree and concentrated lemon juice at the low level required by current laws for baby and organic foods (15, 16). SANNINO:JOURNAL OF AOAC INTERNATIONAL VOL. 87, NO. 4, 2004 991 Received November 5, 2003. Accepted by JS February 11, 2004. Corresponding author's e-mail: annasannino@yahoo.it. Downloaded from https://academic.oup.com/jaoac/article-abstract/87/4/991/5657094 by guest on 22 July 2020