Determination of Residues of 7 Nematocides in Soil by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry with Automatic Accelerated Solvent Extraction
By optimizing the extraction and purification conditions,the method mentioned by the title was proposed to determine 7 nematocides in soil samples,including dazomet,fosthiazate,ethoprophos,fensulfothion,oxamyl,fosthietan and dichlofenthion.Soil sample was collected randomly,dried by air,crushed and sieved.An aliquot(10.0 g)was taken,and 15.0 g of diatomaceous earth was added.The mixture was extracted automatically under heating and pressure conditions with the mixed solution of methanol and trichloromethane at volume ratio of 2∶1.The extract was passed through the activated HLB solid phase extraction column for elution by 10 mL of the mixed solution of methanol and acetonitrile at volume ratio of 1∶1.The eluent was blown to near dryness by nitrogen at 45℃,and the residue was dissolved in 1 mL of ethyl acetate.The solution obtained was passed through a 0.22 μm filter membrane,and the filtrate was determined by ultra-high performance liquid chromatography-tandem mass spectrometry.It was shown that linear relationships between values of the mass concentration and the peak area of the 7 nematocides were kept in the range of 0.005-2.0 mg·L-1,with detection limits(3S/N)in the range of 4-25 μg·kg-1.Test for recovery was made according to the standard addition method,giving recoveries in the range of 87.2%-101%,and RSDs(n=6)of the determined values in the range of 1.5%-3.8%.The proposed method was used for the analysis of actual samples,and dazomet,fosthiazate,ethoprophos,fensulfothion and dichlofenthion were detected with detection amounts ranged from 14.81 μg·kg-1to 124.03 μg·kg-1.
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