Analysis Of Pesticide Residue In Grain With Gel Permeation Chromatography

Forty kinds of common pesticides (16 kinds of organophosphorus,14 kinds of organochlorines and 10 kinds of pyrethroids ) residue on wheat, maize and peanut, which are staple cereals in China, has been studied. The GPC (gel permeation chromatography)– GC (gas chromatography) method was established by extracting with proper organic solvents and purifying with proper method, and then successfully determined the 24 kinds of selected organochlorines and pyrethroids residues.Firstly, the grain samples was extracted by acetonitrile-water(10+20) , purified by gel permeation chromatography (GPC) so as to remove large molecular weight dockages like pigments, fats and so on. Then the cut-off time was determined in accordance with the elution curve of blank samples and the standard pesticides elution profile by GPC purification. Lastly, the GPC-GC/ECD method was established for the determination of 24 kinds of organochlorine and pyrethroid pesticide residues. Recovery rates ranged from 67.8% to 123%,the relative standard deviations from 0.4% to 11%, and the lowest detection limit from 1.3μg/kg to 12μg/kg for the standard pesticides accession experiment, which satisfys the requirement of pesticides determination. The method was easy, fast, sensitive, had good purification effect and was completely fit for quick analysis of multiple pesticide residues on grain.The determination effect of pesticide residues on grain sample between purified by GPC and treated by GB/T 5009,146- 2008 was compared by the accession experiment of 24 kinds of standard organochlorines and pyrethroids. Recovery rates of GB/T 5009,146-2008 purification were 10%~15% lower than GPC purification.Sixteen kinds of organophosphorus pesticide residues in wheat, maize and peanut samples were determined by GC/FPD without GPC purification, and the baselines were stable. All of recovery rates were from 65.6% to 111% except methamidophos,acephate, Omethoate and monocrotophos, and he lowest detection limit was 0.2μg/kg~1.7μg/kg, which was fit for pesticide residues determination.The wheat and maize samples harvested in summer and autumn in 2009 in Shangqiu and Nanyang, Henan province were collected from farmers and state depots respectively, then their pesticide residues were determined the new- established methods. The results showed that only 2 kinds of organophosphorus pesticide residues were detected in the wheat samples collected from shangqiu farmer.