A reversed micelle based two-phase solvent bar microextraction (RM -SBME) was developed for extraction of warfarin in human plasma sample for the first time. The reverse micelle of a cationic surfactant (hexadecyltrimethylammonium bromide) in 1-octanol was used as supported and acceptor phase in SBME. In this process, the analyte was extracted from aqueous samples into a reverse micelle impregnated and also filled in the wall pores and lumen the polypropylene hollow fiber membrane by the electrostatic interactions between the analyte and the surfactant head groups. The porous polypropylene membrane acted as a filter to prevent potential interfering materials from being extracted, and no additional cleanup was required [1]. The influences of extraction parameters affecting extraction efficiency of warfarin including sample solution pH, surfactant concentration and extraction time were studied using central composite design optimization method. The analysis of extracted analyte was performed by high performance liquid chromatography with ultra violet detector. Under the optimum condition, warfarin was extracted with extraction recovery of 97.8% that pertained to enrichment factor of 260. A good linearity over a concentration range 1-600 ng mL-1 with correlation coefficient value of 0.9989 was provided by the current method. Limits of detection and inner and inter-day relative standard deviation were 0.3 ng mL-1 and less than 4.4%, respectively. The proposed method was compared to conventional SBME, and illustrated higher extraction efficiency. The method with bar of 3 cm and acceptor phase volume of 8.5 μL is environmentally green/ friendly method. The proposed method is considered as a simple and efficient method for the determination of warfarin in plasma sample.
