Journal of Chromatography A, 1102 (2006) 1–10 Development of a multiresidue method for analyzing herbicide and fungicide residues in bovine milk based on solid-phase extraction and liquid chromatography–tandem mass spectrometry Sara Bogialli a , Roberta Curini a , Antonio Di Corcia a,∗ , Aldo Lagan` a a , Anna Stabile a , Elena Sturchio b a Dipartimento di Chimica, Universit` a “La Sapienza”, Piazza Aldo Moro 5, 00185 Rome, Italy b Istituto Superiore per la Prevenzione e la Sicurezza del Lavoro (ISPESL), Via Urbana 167, 00184 Rome, Italy Received 6 June 2005; received in revised form 26 September 2005; accepted 11 October 2005 Available online 27 October 2005 Abstract This report describes a liquid chromatography (LC)–tandem mass spectrometry (MS) multiresidue method for determining traces of 30 base/neutral/acid herbicides and fungicides in bovine whole milk. Four milliliters of milk was spiked with the analytes and two surrogate ana- lytes (SAs) and then diluted with 35 mL of a water/methanol solution (50:50, v/v). This mixture was passed through a 0.5-g Carbograph 4 TM cartridge. After washings, analytes were re-extracted by back-flushing the cartridge with 1.5 mL of methanol followed by 6 mL of methylene chloride/methanol (80:20, v/v), 50 mmol/L formic acid. After partial solvent removal down to about 0.1, 0.15 mL of 1 mmol/L formic acid aqueous solution and an internal standard (IS) were added. After filtration, 50 L of the final extract was then introduced into the LC analytical column. During the chromatographic run, the MS system was operated in both positive and negative ion modes. MS data acquisition was performed in the multi-reaction monitoring mode, selecting two precursor ion > product ion transitions for each target compound, except for pentachlorophenol. On analyzing six milk samples from different sources, absolute recovery of the analytes and the two SAs ranged between 78% and 104% with RSDs not larger than 13%. The accuracy of the method at three different spike levels was assessed by adding the two SAs to analyte-containing milk samples and varied between 82% and 120% with RSDs not larger than 11%. Limits of quantification were estimated to range between 0.008 and 1.4 g/L. Compared to the Carbograph 4 cartridge, one filled with a N-vinylpyrrolidone-m-divinylbenzene co-polymer (Oasis HLB TM ) sorbent was much less efficient in recovering several of the acidic herbicides considered and, in addition, its relative final extract produced a severe negative matrix effect that drastically weakened ion signal intensities of several non acidic analytes. © 2006 Elsevier B.V. All rights reserved. Keywords: Herbicides; Fungicides; Bovine; Milk; Solid-phase extraction; LC–MS/MS 1. Introduction The problem of environmental contamination by persis- tent pesticides evokes major concern due to the presence of their residues in the environment and human tissues. Pesti- cide residues in food and animal feed are of interest because pesticides enter the human system through direct consumption of contaminated food or through milk, meat, and other prod- ucts obtained from animals that feed on contaminated feed and fodder. ∗ Corresponding author. Fax: +39 06 49913680. E-mail address: antonio.dicorcia@uniroma1.it (A. Di Corcia). In terms of quantity, herbicides and fungicides represent the largest group of chemicals used as plant protection agents. Her- bicides are also used on pasture and hayfields to control perennial weeds such as wild garlic and onion, which can cause off odors and off-taste in milk. The contamination of milk with an herbi- cide or fungicide depends on its stability, its mode of application, the duration of the intake or exposure, and its metabolic fate in the animal. Occurrence of herbicides in bovine milk has been reported by several authors [1–4]. To ensure the safety of milk for consumers, Directive 98/82/EC [5] has laid down maximum residue limits (MRLs) for several herbicides and fungicides. The concentrations of herbicides and fungicides in milk are expected to be generally rather low and they cannot be detected directly in the raw material. The multiresidue determination of 0021-9673/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2005.10.011