Extraction of trace amounts of pioglitazone as an anti-diabetic drug with hollow fiber liquid phase microextraction and determination by high-performance liquid chromatography-ultraviolet detection in biological fluids.

The applicability of hollow fiber liquid phase microextraction (HF-LPME) for extraction and preconcentration of trace amounts of pioglitazone (PGL) as an anti-diabetic drug in biological fluids, prior to determination by high-performance liquid chromatography (HPLC), was evaluated. In this technique, the target drug was extracted into di-n-hexyl ether immobilized in the wall pores of a porous hollow fiber from 10 mL of the aqueous sample (source phase, SP) with pH 8.0, and then back extracted into the receiving phase (RP) with pH 2.2 located in the lumen of the hollow fiber. The extraction occurred due to a pH gradient between the two sides of the hollow fiber. After extracting for a prescribed time, 24 microL of the RP solution was taken back into the syringe and injected directly into a HPLC instrument for quantification. The Taguchi orthogonal array (OAD) experimental design with an OA(16) (4(5)) matrix was employed to optimize the HF-LPME conditions. Different factors affecting the HF-LPME efficiency such as the nature of organic solvent used to impregnate the membrane, pH of the SP and RP, stirring speed, extraction time and ionic strength were studied and optimized. Under the optimum conditions (di-n-hexyl ether as membrane impregnation solvent, pHs of the SP and RP equal to 8.0 and 2.2, respectively, extraction time of 30 min, stirring speed of 500 rpm and 10% (w/v) NaCl for adjusting the ionic strength), preconcentration factor of 180, linear dynamic range (LDR) of 2.5-250 microg L(-1) with good correlation of determination (r(2)>0.998) and limit of detection (LOD) of 1.0 microg L(-1) were obtained for the target drug. The percent relative intra-day and inter-day standard deviations (RSDs%) based on five replicate determinations were 4.7 and 15%, respectively. Once LPME was optimized, the performance of the proposed technique was evaluated for the determination of PGL in different types of biological fluids such as plasma and urine samples. The results showed that the proposed HF-LPME method could be successfully applied to determine trace amounts of PGL in biological samples.