Determination of Some Selected Pesticide Residues in Apple Juice by Solid - Phase Microextraction Coupled to Gas Chromatography – Mass Spectrometry

HERCEGOVÁ, A., MŐDER, M.: Determination of some selected pesticide residues in apple juice by solid-phase microextraction coupled to gas chromatography – mass spectrometry. Acta univ. agric. et silvic. Mendel. Brun., 2011, LIX, No. 1, pp. 121–128 The performance of solid phase microextraction (SPME) for enrichment of pesticides from apple juice was investigated. Samples were diluted with water, extracted by solid-phase microextraction and analysed by gas chromatography using mass-spectrometry detector (MSD) in selected ion monitoring mode (SIM). The method was tested for the following pesticides used mostly in fruit culturing at Slovakia: tebuthylazine, fenitrothion, chlorpyrifos, myclobutanil, cyprodinil, phosalone, pyrimethanil, tebuconazole, kresoxim-methyl, methidathion, penconazole. All pesticides were extracted with polydimethylsiloxane fi bre 100μm thickness. The linear concentration range of application was 0.05 μg dm−3–10 μg dm−3. The method described provides detectabilities complying with the maximum residue levels (MRLs) set by regulatory organizations for pesticides in apple juice matrices. The solvent – free SPME procedure was found to be quicker and more cost eff ective then the solvent extraction methods commonly used. solid phase microextraction, pesticide residues, apple juice, gas chromatography-mass spectrometry The analysis of nutrients, fl avour and contaminated chemicals in food has been a challenge to many researches for a long time. Production of safe and healthy food is a key priority of EU and problem of contamination of food commodities from pesticide use of is a great social importance for Partner countries. Fresh and processed apples are mostly used as a baby food or for production of apple juice in Slovakia. The pesticides to be studied were chosen on the basis of certain criteria. The basis of criterion was their importance for local market, availa bility on the market, and especially their use on crops (apples) producing baby food or apple juice Determination of some selected pesticide residues in apple juice by solid – phase microextraction coupled to gas chromatography – mass spectrometry detector. Studied pesticides were chosen in accordan ce with the consumption of pesticides applied on apple trees in south-west part of Slovakia (http://www.uksup.sk/index.php?n=25), which are amenable to GC analysis and also represent pesticides of a wide range of polarity and other physico-chemical proper ties. The model mixture of 11 pesticides belonging to variety groups (anilinopyrimidins, organophosphorus pesticides, triazines, oxi minoacetate, triazol) of pesticides in apple juice was studied. The existence of MRL (10 μg.kg−1 for baby food) established by Codex Alimentarius Commission of FAO/WHO was checked. Analysis of real – life samples of apples might leads to problems with tolerance of GC system. Separation of target analytes from the matrix is the primary and o en the most diffi cult step in analysis. The currently used protocols for the determination of pesticides from liquid samples involve liquidliquid extraction (LLE), or solid-phase ex122 A. Hercegová, M. Mőder traction (SPE). Standard pesticide-multiresidue protocols licensed by the European Community for non-fatty foods [EN 1528. 1996] use overall solvent extractions of fruits and GC-ECD or GC-MS analysis (Schenck et al., 2002; Lacassie et al., 1998; Anastassiades et al., 2003; Ripley et al., 2000; Navickiene et al., 2001). They all require a further time and solvent consuming clean up by column chromatography (Schenck et al., 2002), or gel permeation chromatography. Actual method development strives to reduce or even avoid any toxic solvent for sample preparation. Solvent – free sample preparation techniques base on the sorptive extraction of analytes by polymer coating on solid surface such as solid phase microextraction, and stir bar sorptive extraction (SBSE). Both procedures have been demonstrated as fast, effi cient and environmental-friendly alternatives to LLE and SPE in pesticide determination from liquid matrix. Solid phase microextraction introduced by Pawliszyn and co-workers allows simultaneous extraction and pre-concentration of analytes from sample matrix, eliminating some disadvantages of conventional techniques. The principles and applications of novel introduced sorptive extraction methods have been reviewed recently (Baltussen et al., 2002). Baltussen described and compared their new approaches of sorptive extraction. The most of the techniques presented such as SBSE or open tubular trapping (OTT), and gum-phase extraction (GPE) requires additional equipment for thermodesorption. In previous investigations concerning multiresidue screening of pesticides in vegetables and fruits the sorptive extraction techniques proved to be very sensitive and feasible in practice, also suited for automatic processing and high throughput analyses (Sandra et al., 2003). Solid phase microextraction has been applied to the analysis of a range of pesticides and can off er solution to the above issue at a low cost. SPME has been widely used for the analysis of pesticides in water (Lambropoulou et al., 2002; Goncalves et al. 2004; Beceiro-Gonzalez et al., 2007; Xu et al., 2007), fewer data exist on its application to the analysis in other matrices such as soil (Zambonin et al., 2000), sediment, food (Zambonin et al., 2000; Navalon et al., 2002; Kataoka et al., 2000; Chaia et al., 2009), and beverages (Zambonin et al., 2002; Zambonin et al., 2004). In this work we describe a method, proposed for the analysis of pesticide resi dues in apple juice, using a sample preparation step by SPME. MATERIALS AND METHODS