Determination of some Beta-2-agonists in bovine urine with liquid phase microextraction by capillary electrophoresis and gas chromatography mass spetrometry

In this study two different microextraction methods namely DLLME-SFO and DLLME, were developed and combined with GC-MS and CE for the determination of four ß2?agonists (cimbuterol (CIBT, pKa=9.40), clenbuterol (CBT, pKa=9.63), mabuterol (MBT, pKa=9.63) and mapenterol (MPT, pKa=9.78)) in bovine urine. The use of these ß2?agonists as growth promoters is forbidden. The best results were obtained with CE when 20 mM and pH 9.6 of borax buffer and 0.1 mM of SDS were used as BGE. All separations were performed by fused-silica capillary which has a length of 64.5 cm with inner diameter of 25 ?m. Separation temperature was 32°C a potential of 20 kV was applied and hydrodynamic injection conditions were 50 mbar and 5 s In addition, electrokinetic injection was investigated and it was found that optimum injection time was 11s with water plug for 5 s. GC-MS separations were performed by diphenyldimethyl polysiloxan (5%:95%) fused-silica capillary column (30 m in length, 0.25 mm i.d., 0.25 mm film thickness) and analytes were derivatised with BSTFA:TMCS (99:1). The limits of detection (LOD) for CBT, MBT, MPT and CIBT were 1.9, 1.8, 3.4 and 37.0 ?g L-1 respectively in CE. The limits of detection (LOD) for CBT, MBT, MPT and CIBT were 0.08, 0.07, 0.05 and 0.29 ?g L-1 respectively in GC-MS. After the evaluation of validation parameters for both of the developed methods, it was concluded that the methods were selective, sensitive, precise and accurate.