ELECTROPHORESIS, vol.34, no.6, pp.854-861, 2013 (SCI-Expanded)
Dispersive liquidliquid microextraction based on solidification of floating organic drop (DLLMESFO) was for the first time combined with field-amplified sample injection (FASI) in CE to determine four 2-agonists (cimbuterol, clenbuterol, mabuterol, and mapenterol) in bovine urine. Optimum BGE consisted of 20 mM borate buffer and 0.1 mM SDS. Using salting-out extraction, 2-agonists were extracted into ACN that was then used as the disperser solvent in DLLMESFO. Optimum DLLMESFO conditions were: 1.0 mL ACN, 50 L 1-undecanol (extraction solvent), total extraction time 1.5 min, no salt addition. Back extraction into an aqueous solution (pH 2.0) facilitated direct injection of 2-agonists into CE. Compared to conventional CZE, DLLMESFOFASICE achieved sensitivity enhancement factors of 411046 resulting in LODs in the range of 1.8037.0 g L1. Linear dynamic ranges of 0.1510.0 mg L1 for cimbuterol and 151000 g L1 for the other analytes were obtained with coefficients of determination (R2) 0.9901 and RSD% 5.5 (n = 5). Finally, the applicability of the proposed method was successfully confirmed by determination of the four 2-agonists in spiked bovine urine samples and accuracy higher than 96.0% was obtained.