Simultaneous Determination of Residues of 14 Anesthetics in Freshwater Fish by Gas Chromatography-Triple Quadrupole Tandem Mass Spectrometry with Pass-Through Solid Phase Extraction

A method for the determination of residues of 14 anesthetics, including eugenol, methyleugenol, isoeugenol, cis-methyl isoeugenol, eugenyl acetate, acetyl isoeugenol, propofol, tricaine, benzocaine, lidocaine, procaine, pramoxine, tetracaine and butacaine, in freshwater fish by gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS) with pass-through solid phase extraction was proposed. The processed sample (2 g) was taken, and 100 μL of 5.00 mg·L^-1 internal standard solution and 5 mL of water were added. The mixture was mixed well by vortex, and settled for 30 min. Acetonitrile (10 mL) was added into above mixture for extraction, and 2 g of sodium chloride was added for salting out stratification. After centrifugation, 5 mL of the supernatant was loaded onto PRiME HLB column, and the effluent was collected. An aliquot (2 mL) was taken, and 50 μL of dimethyl sulfoxide was added. The solution was blown to nearly dryness at room temperature by nitrogen. Then the residue was redissolved with 1.0 mL of acetone, and filtered by 0.22 μm microporous membrane. The filtrate was determined by GC-MS/MS. HP-5MS UI capillary column was used to separate target compounds, and electron impact ion source and multiple reaction monitoring mode were used for detection, with internal standard method for quantification. It was shown that the linear ranges of working curves of 14 anesthetics were 0.005-0.400 mg·L^-1, with the same detection limits of 0.001 mg·kg^-1. Test for recovery was made on negative sample as matrix at 3 concentration levels by addition standard method, giving values of recovery of intra-day and inter-day were in the range of 75.3%-120%, and precision (n=6) of intra-day and inter-day were in the range of 1.3%-10%. This method was applied to the analysis of 33 actual samples, and eugenol was detected in 15 samples, with detection amounts in the range of 0.013 6-0.462 mg·kg^-1.