Simultaneous extraction and determination of trace amounts of olanzapine and fluoxetine from biological fluids: comparison of conventional hollow fiber supported liquid phase microextraction and pulsed electrically assisted liquid-phase microextraction techniques

In the current work, hollow fiber liquid phase microextraction (HF-LPME) and pulsed electromembrane extraction (PEME) coupled with high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection were compared for the extraction of olanzapine (OLZ) and fluoxetine (FLX) from human plasma and urine samples. The influences of extraction parameters affecting the extraction efficiency of OLZ and FLX were studied and optimized for both methods. Under passive extraction conditions, FLX and OLZ were extracted from alkaline samples (pH = 12) into 1-octanol immobilized in the pores of a porous hollow fiber of polypropylene (SLM), and then transported into 25 mu L of 25 mM HCl as the acceptor solution. Under electrokinetic migration conditions, FLX and OLZ were transported under applied voltage from acidic sample solutions (pH = 6) through 2-nitrophenyl pentyl ether (NPPE) immobilized in the pores of the hollow fiber into 25 mu L of 10 mM HCl as the acceptor solution. Under the optimized conditions, preconcentration factors in the range of 59 to 78 and 43 to 65 for PEME and HF-LPME, respectively, and satisfactory repeatabilities (3.4 < relative standard deviation [RSD] < 7.8) were obtained in different matrices. The obtained recoveries of the drugs in the range of 82.6-103.1% indicated the excellent capability of the developed methods for simultaneous extraction of FLX and OLZ from complex matrices. The results showed that in comparison with HF-LPME based on pH gradient, PEME is a more effective transport process, providing high extraction efficiencies in a short time.