The Impact of Pesticides - Academy Publish

epeatable results, and extends the capillary column lifetime (Diaz et al., 1997;Rimkus et al., 1996). Several approaches have been attempted to eliminate coextractedinterference from extracts, including SPE, d-SPE, GPC and ultra-filtration(UF).Solid-phase Extraction (SPE)Efficient clean-up is indispensable for preventing matrix effects in multiresidueanalysis of pesticides in food by liquid and gas chromatography coupled to massspectrometry. Different than traditional detector systems, liquid chromatography(LC) and gas chromatography (GC) coupled to mass spectrometry (MS) provide ahigh degree of selectivity and sensitivity. Co-eluting matrix components may resultin (i) false negatives, (ii) false positives, or (iii) inexact quantification caused by ionsuppression or ion enhancement, depending on the matrix. The same problems holdtrue for GC–MS, but different matrix compounds can interfere and differentmechanisms are responsible for these matrix effects (Oellig and Schwack, 2011).Solid-phase extraction (SPE) has been used as a purification step to removeinterfering compounds co-extracted with all classes of pesticides from a largeselection of foods of animal origin (LeDoux, 2011).The extraction clean-up typically requires, after the extraction, a multisteppurification based on the use of various adsorbents, such as Florisil, C18, Alumina,and Silica gel, in order to eliminate interfering substances and matrix fatty materials,which can decrease rapidly the column efficiency, and affect severely the accurateidentification and quantification of the analytes (Nardelli et al., 2010).For analysis of food a widely used strategy is the combination of SPE-QuEChERS,with the advantage the relatively low solvent consumption, at least as compared toprevious liquid partitioning based methods. In the case of fatty matrices, the cleanupwas performed using a combination of PSA, graphitized carbon black (GCB) andC18. Recently, an alternative procedure similar to QuEChERS, but performed theclean-up step using SPE in cartridges (so that it can be easily automated) has beenreported. It offers advantages in terms of solvent consumption and increasedautomation of the procedure (Gilbert-López et al., 2009; Beyer and Biziuk, 2010).A multiresidue method for the determination of organochlorine pesticides in fishfeed samples was developed and optimized. The method is based on a clean-up stepof the extracted fat, carried out by liquid–liquid extraction on diatomaceous earthcartridge with n-hexane/acetonitrile (80/20, v/v) followed by solid phase extraction(SPE) with silica gel–SCX cartridge, before the identification and quantification ofthe residues by gas chromatography–triple quadrupole tandem spectrometry (GC-MS/MS). No matrix effects or interfering substances were observed in fish feedanalyses. The proposed method allowed high recoveries (92–116%) of spikedextracted fat samples at 100 μg kg −1 , and very low LODs (between 0.02 and 0.63 μgkg −1 ) and LOQs (between 0.05 and 2.09 μg kg −1 ) determined in fish feed samples(Nardelli et al., 2010).An analytical method was developed to determine the phenoxyacid herbicides 2,4-D, MCPA and mecoprop in kidney tissue from animals. Samples were Soxhletextracted using diethyl ether and the extracts cleaned-up using anion. Exchangesolid phase extraction cartridges. Analysis was performed using liquidAcademyPublish.org - The Impact of Pesticides369