Study On Determination And Analysis Of Carbamate Pesticide Residues In Vegetables In Lhasa

This paper studied the two different purification methods of solid phase extraction and gelpermeation chromatography (GPC),the determination techniques of high performance liquidchromatography (HPLC) for determination and analysis of carbamate pesticide residues in vegetables.Comparative analysis of different conditions for the solid phase extraction,gel permeationchromatography in the purification process and high performance liquid chromatography (HPLC) in thedetermination process were achieved, the optimum conditions of determination and analysis for thecarbamate pesticide residues in vegetables under plateau conditions were explored.The optimumconditions are the following.(1)After extracting of samples with acetonitrile,the samples were purifing by SPE;in40℃ofconcentrated tempreture of Nitrogen the apparatus was satisfied; purification effect was better with NH2solid-phase extraction column;when elution volume in8-10mLwith the eluting liquid ofMethanol-dichloromethane(V5:V95),the pesticides were eluted perfectly.(2)When the collecting times of effluent liquid were15.5～27min in the samples purification byGPC, the recovery rate of seven carbamate pesticides were best.(3)After purifing of the two different methods,the samples were dissolved inmethanol-water(V60:V40),the recovery rate of the method was better.(4)The samples were determined by HPLC with post-column derivatization fluorescencedetector;the wavelength of fluorescence detector were λex=330nm and λem=465nm;when the analyticalcolumn was C18, it was much suitable for the analysis of seven carbamate pesticides;the mobile phasewas a mixture of methanol-water by gradient elution and column temperature was at30℃;thepost-column derivatization conditions: the flow velocity of0.05mol/L NaOH solution was0.3mL/minand the flow velocity of OPA was0.3mL/min; the tempreture of reactor was80℃and derivatizationtempreture was at room temperature;the sample introduction amount was10uL.(5)Good linear correlation for standard curves of seven carbamate pesticides were found in theconcentration range of0.10~0.50mg/L,the correlation coefficients were0.9986～0.9995,the limits ofdetection were0.008～0.010mg/kg.(6)The recovery rate of the method were between80.4%and95.2%,the relative standarddeviations were between2.3%and9.4%for seven carbamate pesticides by SPE purification method;the recovery rate of the method were between80.1%and95.5%,the relative standard deviations werebetween2.4%and9.2%for seven carbamate pesticides by GPC purification method.The limits of detection, recoveries of method and precision of the optimum conditions could meetthe requirements of analysis for carbamate pesticide residues in vegetables.On the basis of studing the determination techniques of carbamate pesticide residues invegetables,we also studied the problems of carbamate pesticide residues in main vegetables from2009to2011in Lhasa. The vegetables from part of supermarkets,farm products markets,wholesale marketsand the surrounding production bases in Lhasa for simultaneous determination of seven carbamatepesticide residues were sampled,random sample of vegetables,1200. Based on testing results,we did safety evaluation, analysed pollution situations and levels of carbamate pesticide residues for vegetablesin Lhasa during the three years,studied the present pollution conditions and causes of carbamatepesticide residues in vegetables, in accordance with the actual situation of our own locality, proposedeffective comprehensive prevention and control measures for the carbamate pesticide residues pollutionin vegetables in our city. From2009to2011, pollution situations of carbamate pesticide residues invegetables in Lhasa as follows:(1) Superscalar rates of carbamate pesticides had decreased from6.00%in2009to2.50%by2011,superscalar quantities of22kinds of vegetables had reduced from16in2009to8by2011,superscalarquantities of5vegetable sorts had also declined from4in2009to3by2011.(2)All kinds of carbamate pesticides that be used in vegetables have changed, there were4kinds ofcarbamate pesticides in superscalar pesticides in2009,superscalar quantities of carbamate pesticideswere only2in vegetables to2011,superscalar sorts of carbamate pesticides were decreased.Superscalarpesticides were mainly carbofuran and aldicarb.(3)In2009-2011, superscalar rates of carbamate pesticides for22kinds of vegetables were muchserious in leafy vegetables and leguminous vegetables;leafy vegetables were mainly Chinesecabbages,celeries, leeks and so on;leguminous vegetables were mainly cowpea and string beans.(4)In2009-2011, the superscalar rates were higher in the spring and autumn than in the summerand winter during the four seasons.(5)Four kinds of different sampling places including vegetable production bases, part of thesupermarkets, wholesale markets and farm products markets are19a total of sampling spots.In2009-2011,only vegetable production bases in which the superscalar rate was declined,other threesampling places in which the superscalar rates were fluctuant trends.Thus it can be seen there were still some problems about carbamate pesticide residues in vegetablesin Lhasa,the government and relevant departments still need to strengthen management.