The Impact of Pesticides - Academy Publish

solvent. The cold extract containing precipitated lipids was promptly filtered withfilter paper to prevent melting lipids.Nowadays, most analytical methods for pesticide residues in fatty foods (e.g. foodof animal origin) are designed predominantly for the out-moded organochlorinecompounds and employ solvents such as hexane, acetone, ethyl acetate, anddichloromethane for extraction in order to dissolve the lipids (LeDoux, 2011).However, intensive and time-consuming clean-up, such as gel permeationchromatography (GPC), is usually needed to remove the co-extracted fat from theextracts prior to the analytical step. From the possibilities of the QuEChERS methodoptimization, especially the d-SPE step, this method appears as an option tosubstitute a nonpolar solvent during extract the pesticide residues.Gel Permeation Chromatography (GPC)GPC is a method based in the principle size exclusion. This mode of purification iswidely used in the area of pesticide residue analysis, wich is considered a goodtechnique for the separation of low molecular mass compounds (up to 400 µm) suchas pesticides from high molecular mass compounds such as lipids (600 to 1500 µm)(Buldini et al., 2002; Diaz et al., 1997; Rimkus et al., 1996).GPC systems comprises a LC pump a fraction collector and a detector (optional).The columns are made from polymeric porous microspheres, which enables theseparation of compounds according to their molecular weights. Using this principle,pesticide fraction is separated from the high molecular weight lipids fractions(Gilbert-López et al., 2009). In order to reach a higher sample throughput, Focant etal. (2001) replaced slow GPC purification with high-capacity disposable silica(HCDS) columns containing 28 g of acidic, 16 g of basic, and 6 g of neutral silica;this allowed up to 4 g of lipids for each sample to be retained. The HCDS column isadded to the classic set of columns and is the first one in contact with the sample.Such a column system has found application in purifying extracts from samplescharacterized by a high lipid content, e.g., poultry, fish and eggs (Beyer and Biziuk,2008).GPC has therefore been widely used for cleaning up extracts from foods of animalorigin with a high fat content. However, co-extracted compounds, includingremaining trace amounts of lipids, can reach the GPC eluate and then interfere withthe subsequent analysis. Complex samples such as fish, meat, and other fatty matrixextracts often require a two-step clean-up combining gel permeationchromatography and adsorption chromatography in series (Diaz et al., 1997; Rimkuset al., 1996).A clean-up step by GPC was applied to remove fat and other matrix compoundsfrom meat samples from chicken, pork and lamb (Frenich et al., 2006a), liver(Frenich et al., 2007) and meat (Frenich et al., 2006b) to determine pesticidesorganochlorine (OCPs) and organophosphorus (OPPs). Clean-up was done by GPC.Ethyl acetate–cyclohexane (1:1, v/v) was used as the mobile phase of the GPCsystem at a column flow of 5mLmin −1 . The determination was carried out by gaschromatography with electron impact ionization tandem mass spectrometry (GC–EI-MS/MS) using a triple quadrupole (QqQ) analyzer.AcademyPublish.org - The Impact of Pesticides371