Journal of Chromatography A, 1036 (2004) 161–169 Application of liquid chromatography with electrospray tandem mass spectrometry to the determination of a new generation of pesticides in processed fruits and vegetables Anna Sannino ∗ , Luciana Bolzoni, Mirella Bandini Stazione Sperimentale per l’Industria delle Conserve Alimentari, Viale F. Tanara 31/A, 43100 Parma, Italy Received 4 December 2003; received in revised form 23 February 2004; accepted 27 February 2004 Abstract This paper describes a method for the sensitive and selective determination of 24 new pesticide residues (azoxystrobin, trifloxystrobin, kresoxim-methyl, fenazaquin, indoxacarb, fenothiocarb, furathiocarb, benfuracarb, imidachloprid, dimethomorph, fenpyroximate, hexythia- zox, tebufenpyrad, tebufenozide, difeconazole, fenbuconazole, flusilazole, paclobutrazol, tebuconazole, tetraconazole, bromuconazole, etofen- prox, fenhexamid, pyridaben) in apple puree, concentrated lemon juice and tomato puree. A miniaturized extraction–partition procedure requiring small amounts of non-chlorinated solvents was used. The extracts are analyzed by liquid chromatography–electrospray ionization tandem mass spectrometry (LC–ESI–MS–MS) without any further clean-up step. The pesticides are separated on a reversed-phase polar col- umn using a gradient elution. Fifty-five simultaneous MS–MS transitions of precursor ions were monitored (two or three for each pesticide). Studies at fortification levels of 0.001–0.020 and 0.010–0.200mg/kg gave mean recoveries ranging from 76 to 106% for all compounds, except for imidacloprid, with (R.S.D.s) ≤15%. The excellent sensitivity and selectivity of LC–MS–MS method allowed quantitation and identification at low levels also in difficult matrices with a run time of 20 min. With the developed method almost 100 samples of commercial fruit products (nectars, juices, purees) were analyzed. None of samples contained residues higher than 0.010 mg/kg. © 2004 Elsevier B.V. All rights reserved. Keywords: Fruits; Vegetables; Food analysis; Pesticides 1. Introduction Use of agrochemicals at various stages of cultivation and during post-harvest storage play an important role in food protection and quality preservation. Therefore, thorough monitoring of pesticide residues is crucial for proper assessment of human exposure to pesti- cides through foods. Maximum residue limits in foodstuffs have been set by Government agencies and European Union Commission to guarantee consumer safety and to regulate international trade [1,2]. Analytical methodologies employed must be capable of residue measurement at very low levels and must be also provide unambiguous evidence to confirm both the identity and the quantity of any residues detected. ∗ Corresponding author. Tel.: +39-0521-795203; fax: +39-0521-7718929. E-mail address: lra.ssica@libero.it (A. Sannino). Most pesticides are volatile and thermally stable and therefore the most frequently used methods rely on gas chromatographic (GC) separation [3–5] and detection with selective and sensitive detectors such as electron-capture detection (ECD), nitrogen–phosphorus detection (NPD) and mass spectrometry (MS). However, the number of compounds that cannot be de- termined by GC because of their poor volatility, high po- larity and thermal instability has grown dramatically in the last few years. Agrochemicals belonging to carboxamide, quinazolin, phenoxypyrazol, strobilurin, pyrimidine, triazol, carbamate, neonicotinoid, morpholine classes are represen- tative of the newly introduced molecules. Nowadays, liquid chromatography coupled with mass spectrometry (LC–MS) is becoming one of most powerful techniques for the residue analysis of polar, ionic or low volatility pesticides in fruits and vegetables [6,7]. Mod- ern LC–MS instruments employing atmospheric pressure ionization (API) provide excellent sensitivity and selectiv- ity that enables analysis of target analytes at trace levels. 0021-9673/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2004.02.078