Solvent bar microextraction using a reverse micelle containing extraction phase for the determination of warfarin from human plasma by high-performance liquid chromatography.

For the first time, solvent bar microextraction using a reverse micelle RMM-SBME as extraction phase was developed for extraction of warfarin in human plasma sample. The reverse micelle of a cationic surfactant (hexadecyltrimethylammonium bromide) in 1-octanol was applied 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 influences of fundamental 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, the sample containing 40ngmL of warfarin was extracted with extraction recovery of 97.8% that pertained to enrichment factor of 260. A good linearity over a concentration range 1-600ngmL 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 0.3ngmL and less than 4.4%, respectively. This method was compared to conventional SBME, and illustrated higher extraction efficiency. The method needs minimal sample preparation time since the porous hollow fiber membrane prevents from being extracted potential interfering materials, acts as a filter, and any extra cleanup was not required. The method with bar of 3cm and acceptor phase volume of 8.5μL is environmentally green/friendly method. The proposed method was successfully applied for the preconcentration and determination of warfarin in plasma sample.