HPLC Determination of Residual Amount of Thiabendazole in Dried Tangerine After Separation by SPE and Ion-exchange

Sample was soaked with dil.H3PO4 (1+999) solution for 2 h,agitated for 20 min ultrasonically and centrifuged for 3 min after diluting to 50 mL.An aliquot of the supernatant solution was taken for purification by passing through the ENVITM C18 SPE column.A mixed solution,containing 0.1 mol·L-1 KH2PO4 of pH 3.0 and acetonitrile mixed in the ratio of 70 to 30 by volume (which was also used as mobile phase) was used as eluant to elute the analyte from the SPE column,and the eluate obtained was used for HPLC determination.The LC-SCX column was used as ion-exchange chromatographic column and the mixed solution mentioned above was used as mobile phase in the HPLC analysis with fluorescence detection at the wavelengths of 307 nm (λex) and 359 nm (λem).Range of linearity was found in the concentration range of 0.5-100.0 μg·L-1 of thiabendazole against values of relative peak area.Test for recovery was performed at 3 concentration levels,giving values of av.recovery in the range of 88.0%-95.0% and RSD′s (n=6) in the range 3.1%-5.0%.