QUANTITATIVE MULTI-RESIDUE DETERMINATION OF BETA-AGONISTS IN BOVINE URINE USING ONLINE IMMUNOAFFINITY EXTRACTION COUPLED-COLUMN PACKED CAPILLARY LIQUID-CHROMATOGRAPHY TANDEM MASS-SPECTROMETRY

This report demonstrates the potential of on-line immunoaffinity extra ction and coupled column packed capillary liquid chromatography-ion sp ray tandem mass spectrometry for multi-residue determination of five b eta-agonists, clenbuterol, mabuterol, mapenterol, methylclenbuterol, a nd tolubuterol, in bovine urine using an automated column switching sy stem. Trace enrichment and preliminary sample cleanup was performed on -line using bovine urine diluted with phosphate-buffered saline. The c olumn switching process involves trapping the target analytes onto a m ini-bore immunoaffinity column, whereupon the target analytes are rele ased from the immunoaffinity column onto a trapping column and subsequ ently eluted onto a packed capillary analytical column. The latter pac ked capillary column was used to provide the optimum sensitivity for i on spray LC-MS-MS analyses. The three-column system consists of a 2.0 mm I.D. immunoaffinity column, al mm I.D. reversed-phase trapping colu mn and a 320 mu m I.D. packed capillary analytical column. Both qualit ative and quantitative results are presented for the multi-residue det ermination of the target beta-agonists from the complex urinary matrix . Using tolubuterol as an internal standard, the quantitative data sho wed good linear response within the concentration ranges studied. Lowe r levels of quantitation were 50 part per trillion (ppt) for clenbuter ol and methylclenbuterol, 20 ppt for mabuterol and 10 ppt for mapenter ol. The bovine renal elimination is described using the technique for one of the beta-agonists, clenbuterol. The concentration of clenbutero l was detectable 15 days after the cessation of oral administration.