Development of carbon-nanotube-assisted electromembrane extraction in the two-phase mode combined with GC for the determination of basic drugs.

In this work, carbon-nanotube-assisted electromembrane extraction in the two-phase mode combined with GC was developed for the preconcentration and determination of basic drugs in body fluids. The multiwalled carbon nanotubes dispersed in organic solvent are held in the pores of the porous fiber wall by capillary forces and sonification. The membrane with immobilized carbon nanotubes acts as a sorbent and provides an additional pathway for analyte transport. This study demonstrates that the immobilization of carbon nanotubes in the supported liquid membrane is an excellent approach to enhance the performance of the extraction. Optimization of the variables affecting this method was carried out in order to achieve the best extraction efficiency. Optimal extractions were accomplished with octanol as the extraction solvent, 50 V as the driving force and pH 7.4 in the sample solution with the whole assembly agitated at 1000 rpm for 20 min. Under the optimized extraction conditions, the proposed technique provided good linearity (R(2) > 0.9990), repeatability (3.5-3.8%), low LODs (1.5 ng/mL), good preconcentration factors (292-316) and high recoveries (80-87%). Finally, this method was successfully used for the determination of tramadol and methadone in different body fluids including plasma and urine samples.