Determination of Tranquilizer and Their Metabolites Residues in Aquatic Products by High Performance Liquid Chromatography-Tandem Mass Spectrometry

A method for determination of tranquilizer and their metabolites residues in aquatic products by HPLC-MS/MS was developed. The samples were added with internal standard of diazepam-d(5), methaqualone. d(7) and chlorpromazine-d(6), and then extracted by ethyl acetate under alkaline conditions. Then the extract was dried under nitrogen, and the residues were dissolved in 80% acetonitrile solution and cleaned up with PSA and C-18. Isotope internal standard was used for quantification. The analytes were separated by a Capcell PAK C-18 MG II (100 mmx2. 0 mm, 5 mu m) column, and gradient eluted with a mixed solution of (2 mmol/L ammonium acetate +0.1% formic acid) and methanol. The mass spectrometric analysis was carried out under multiple reaction monitoring mode. Good linearity of the calibration curves was obtained in the concentration range of 0.5-20.0 mu g/kg with the correlation coefficients (R-2) of more than 0.999. The limit of detection for this method was 0.5 mu g/kg and the quantitative limit was 1.0 mu g/kg. The average recoveries at three fortified levels (1, 5 and 10 mu g/kg) were 80.6% - 119.4%, and the RSDs ranged from 0.05% to 14.5%. This method was simple, rapid with high accuracy and sensitivity, and was suitable for detection of tranquilizer residues in aquatic products.