Rapid HPLC Determination of Residues of Malachite Green Crystal Violet and Their Leuco-products in Aquatic Products

HPLC was applied to the simultaneous determination of residual amounts of malachite green, crystal violet and their leuco-products in aquatic products.The sample was extracted with acetonitrile and purified by extraction with CH_2 Cl_2 and passing through SPE column of acidic aluminum oxide The column was eluted with acetonitrile,and the eluate was evaporated to near dryness by rotary evaporation.The residue was taken up with 1.0 mL of acetonitrile which was used for HPLC analysis.The C_(18) column was used as the stationary phase,and solutions of acetonitrile(A) and 0.02 mol·L~(-1) KH_2 PO_4(adjusted to pH 3.0 with H_3 PO_4 )(B) mixed in different ratio by volume were used as the mobile phase in gradient elution.A self-made PbO_2 oxidation column was used for on-line oxidation of the leuco bases of malachite green and crystal violet.Linear relationships between values of peak area and mass concentration of the 4 compounds were found in the same range of 0.3-6.0 mg·L~(-1),with their detection limits(3S/N) less than 1.9μg·kg~(-1).Array diode detection at 588 um was adopted,values of RSD's (n=6) found for the 4 compounds were all less than 2.5%.Sample of canned archovies was analyzed by this method,and test for recovery was made on this matrix by standard addition method giving results in the range of 71.5%to 88.6%.