Method For The Determination Of Pesticide Residues And Key Organic Pollutants In Foods

The application of pesticides in agriculture help to control a wide range of pest and plant diseases, and consequently increase in the harvest productivity is obtained. The toxicity of these compounds makes necessary the monitorization food quality in order to avoid risks to consumers, as well as to regulate international trade. This has led to the development of many multi-residue analytical methods, which allow the simultaneous determination of a several number of pesticides or organic pollutants in food at very low concentration in response to the legislation in many countries.Capillary gas chromatography (GC) with selective detector and mass spectrometry has been the technique selected to the analysis of pesticide residues and organic pollutant (PCBs and PAHs) in foods.1 A GC-MS with selected ion monitoring method was developed for the determination of multiple pesticide residues in concentrated fruit and vegetable juices. Retention time locking (RTL) pesticide database is used to simplifying the editing the SIM ion group and eliminate the tedious SIM method RT updating process after column maintenance . Large volume injection of samples with a programmed temperature vaporizer (PTV) system is discussed, Conditions of split vent flow , purge time ,PTV system temperature and maximum sample volume was optimized . In comparison with conventional methods , the detection limits has been improved by 1 orders of magnitude. By use of stable isotopically labeled pesticides as internal standard , the trueness of quantification in GC/MS analysis could be improved. Deuterium-labeled pesticides (surrogate standards) are used pesticides recoveries were found to be 70%-121% with RSDs of 4.6%-21% (n=6).2 A method for rapid determination of pesticide residues in peanut is described. The pesticide was extracted using acetonitrile from sample, most of lipids in co-extractives were removed by gel permeation chromatography or solid phase extraction. The pesticides was finally determined by gas chromatography / mass spectrometry in selective-ion monitor(SIM)and GC-ECD. The average recoveries and RSD was satisfactory .3 A method for rapid determination of azocylotin in fruit juices is described.The sample was extracted with hexane . The pesticide was derivatized at 50℃for 15 min under supersonic wave with sodium tetra-ethylborate . Mass spectral characteristics of derivatives of Azocylotin was interpreted. Mass spectral analysis was performed in the selected ion monitoring mode at m/z 233 ,315 , 203 and 287.The recovery range was 80% - 90%,with RSD 4.1%-8.9%. The method detection limit 0.01mg/kg.4 A simple and rapid gas chromatographic method for determination of pesticide residues in sulfur-containing vegetables (garlic, onion, green Chinese onion,leek, etc.) was developed. The sulfur-containing vegetables were treated with microwave oven to inactivate enzymes, and were cut into pieces and homogenized. Pesticides in the homogenized sample were extracted with acetonitrile (MeCN) , cleaned up by primary/secondary amine (PSA) solid phase extraction columns, and analyzed for oranochlorine, organophorous, and pyrethroid pesticides using gas chromatography with electron capture detection (GC-ECD) and flame photometric detection (GC- FPD). Recoveries of the pesticides in spiked samples were 70%-110% and with RSD of 3.5%-14.2% . 5 A method for the determination of 16 polycyclic aromatic hydrocarbons(PAHs)in vegetables by solid phase extraction coupled with gas chromatography-mass spectrometry was developed. The samples were extracted with cyclohexane and further cleanup were performed using diluted sulfuric acid and PSA cartridge.. The average recovery was among 60% and 120% ,and relative standard deviation was 8 % to 20% ,and the detection limits ranged from 0.009μg/kg to 0.06μg/kg . The method was used for the determination of PAHs in different real vegetable samples.6 A method is described for the determination of PCBs residue in animal-origin food by gas chromatography with mass spectrometer and electron capture detector. Sample was digested by HCLO4-HAC,and extracted by petroem-ether and cleanedup by concentrated H2SO4 .The recoveries and RSDs were 82%—87.1%,10.2%-16.1%,respectively. For PCB101,138,153,180, negative chemical ionization(GC-NCI-MS )have higher sensitive than GC-EI-MS And GC-ECD.