Establishment of pressurized liquid extraction followed by HPLC-MS/MS method for the screening of adrenergic drugs, steroids, sedatives, colorants and antioxidants in swine feed.

A facile and sensitive multi-residue detection approach of pressurized liquid extraction following high-performance liquid chromatography tandem mass spectrometry was established to detect the residues of adrenergic drugs, steroids, sedative, colorant and antioxidant in feed. The conditions employed for pressurized liquid extraction involved acetonitrile/ethyl acetate (1:1, v/v) as the extracting solvent, the temperature 80°C, two cycles and a static time of 10 min. The extraction was followed by a solid-phase extraction clean-up step. The separation of samples was done by C18 column with the mobile phase of 5 mM ammonium acetate solution and acetonitrile with 0.1% formic acid. The limits of quantification ranged from 0.03 to 1 μg/kg, limits of detection were in a range of 0.01-0.5 μg/kg, and average recoveries were 70.4-98.6%. The pressurized liquid extraction procedure was optimized and overall method was validated in terms of sensitivity, linearity, selectivity, matrix effect, accuracy, recovery and stability of the target drugs in the pressurized liquid extraction extracts solution. The screening method was proved to be fast, selective, accurate and sensitive for screening drugs.