Determination of Residual Difluobenzuron in Wheat by HPLC

High performance liquid chromatography (HPLC) was applied to the determination of residual difluobenzuron (DFBZ) in wheat.DFBZ was extracted from the sample with acetonitrile,and separated on the hypersil ODS C18 column (250 mm×4.6 mm,i.d.5 μm).A mixture of acetonitrile and water,in the ratio of 60+40 by volume,was used mobile phase,at a flow-rate of 1 mL·min-1.UV-detection was made at the wavelength of 254 nm.External standard was used in the determination.Linear relationship between the chromatographic peak height and mass concentration of DFBZ was obtained in the range of 0.2-20 mg·L-1,with correlation coefficient of 0.999 9 and a detection limit (S/N=3) of 0.02 mg·kg-1.Recovery and precision of the method were tested at 3 concentration levels (1.0,0.2 and 0.04 mg·kg-1),giving results of average recovery in the range from 89.4%-90.9%,and values of RSD′s (n=5) in the range of 2.37%-4.15%.