GC-MS Determination of Residual Amounts of 3 β₂-Agonists in Animal Urine

A method of GC-MS for simultaneous determination of residual amounts of 3 β2-agonists, i.e., clenbuterol, salbutamol and ractopamine in animal urine was proposed. Sample was extracted with a mixture of isopropanol-ethyl acetate (30+70) and purified on the MCX column,then derivatized with a mixed reagent of BSTFA-TMCS (99+1). The DB-1MS capillary column was used for GC separation and the selected ion monitoring mode was adopted in MS determination. Linear relationship between values of peak area and mass concentration of 3 β2-agonists were obtained in the same range within 1.00 mg·L-1, with detection limits (3S/N) in the range of 0.2-0.3 μg·L-1. Using blank swine urine samples as matrixes, tests for recovery and precision were made by standard addition method, values of recovery found were in the range of 91.7%-98.7% and RSD′s (n=5) in the range of 3.3%-6.5%.