Cetyl-alcohol-reinforced hollow fiber solid/liquid-phase microextraction and HPLC–DAD analysis of ezetimibe and simvastatin in human plasma and urine

A new cetyl-alcohol-reinforced hollow fiber solid/liquid-phase microextraction (CA–HF–SLPME) followed by high-performance liquid chromatography–diode array detection (HPLC–DAD) method was developed for simultaneous determination of ezetimibe and simvastatin in human plasma and urine samples. To prepare the CA–HF–SLPME device, the cetyl-alcohol was immobilized into the pores of a 2.5 cm hollow fiber micro-tube and the lumen of the micro-tube was filled with 1-octanol with the two ends sealed. Afterwards, the prepared device was introduced into 10 mL of the sample solution containing the analytes with agitation. Under optimized conditions, calibration curves plotted in spiked plasma and urine samples were linear in the ranges of 0.363–25/0.49–25 μg L⁻¹ for ezetimibe/simvastatin and 0.193–25/0.312–25 μg L⁻¹ for ezetimibe/simvastatin in plasma and urine samples, respectively. The limit of detection was 0.109/0.174 μg L⁻¹ for ezetimibe/simvastatin in plasma and 0.058/0.093 μg L⁻¹ for ezetimibe/simvastatin in urine. As a potential application, the proposed method was applied to determine the concentration of selected analytes in patient plasma and urine samples after medication and satisfactory results were achieved. In comparison with reference methods, the CA–HF–SLPME–HPLC–DAD method demonstrates considerable potential in the biopharmaceutical analysis of selected drugs.