Journal of Pharmaceutical and Biomedical Analysis 54 (2011) 1173–1179 Contents lists available at ScienceDirect Journal of Pharmaceutical and Biomedical Analysis journal homepage: www.elsevier.com/locate/jpba Microextraction of mebendazole across supported liquid membrane forced by pH gradient and electrical field Mahboube Eskandari a , Yadollah Yamini b,∗ , Lida Fotouhi a , Shahram Seidi b a Department of Chemistry, School of Science, Alzahra University, Vanak, P.O. Box 1993891176, Tehran, Iran b Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran article info Article history: Received 12 August 2010 Received in revised form 30 November 2010 Accepted 4 December 2010 Available online 14 December 2010 Keywords: Hollow fiber membrane Liquid phase microextraction Electromembrane High performance liquid chromatography Mebendazole abstract In the present study, extraction of mebendazole across a supported-liquid membrane (SLM) was per- formed based on two different driving forces: (1) pH gradient over the SLM, and (2) electrical field sustained over the SLM. The extracted drug concentration was studied using reversed-phase HPLC–UV. At passive extraction conditions, mebendazole was extracted from alkaline samples (0.01 mmol L -1 NaOH) into 1-undecanol immobilized in the pores of a porous hollow fiber of polypropylene (SLM), and then transported into 25 L of 100 mM HCl as the acceptor solution. Under electrokinetic migration condi- tions, mebendazole transported under applied voltage from acidic solutions (100 mmol L -1 HCl) through 2-nitrophenyl octyl ether (NPOE) immobilized in the pores of hollow fiber, into 25 L of 100 mmol L -1 HCl as the acceptor solution. The effects of several factors including the nature of organic solvent, pH of donor and acceptor solutions, extraction time and stirring speed on the extraction efficiency of the drug were investigated and optimized. Under optimal conditions, preconcentration factors (PF) of 211 and 190 were obtained for the drug based on passive transport and electromembrane extraction (EME), respectively. Also, linear range of 0.5–1000 gL -1 with estimation of coefficient higher than 0.994 was obtained for both of the proposed methods. The results showed that EME has higher speed in compari- son with simple passive transport. The methods were successfully applied to extract mebendazole from plasma and urine samples and satisfactory results were obtained. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Methyl-5-benzyl-2-benzimidazole carbamate (mebendazole) is used as an anthelmintic drug. The drug is known to act through irreversible inhibition of glucose uptake in the parasite, leading to depletion of glycogen store which results in a decrease in adenosine triphosphate activity. Only 5–10% of the ingested drug is absorbed from the human gastrointestinal tract [1]. In recent years, a miniaturized approach to supported-liquid membranes (SLM) extraction is liquid-phase microextraction (LPME). The SLM is an organic solvent immobilized in the pores of a porous polymeric membrane. Hollow fiber liquid-phase microex- traction is based on passive diffusion of analytes from sample solution, through a water-immiscible organic solvent immobilized as a SLM in the pores of the wall of a porous hollow fiber into micro-liter volume of acceptor solution filled inside the lumen of the hollow fiber. This configuration creates a three-phase extrac- tion system compatible with HPLC–UV [2,3]. The extraction based on passive diffusion (pH gradient) is limited to basic or acidic ana- ∗ Corresponding author. Tel.: +98 21 82883417; fax: +98 21 88006544. E-mail address: yyamini.modares@ac.ir (Y. Yamini). lytes. For basic compounds, pH of sample has to be adjusted at alkaline region to form neutral analyte and ensure efficient dis- tribution of uncharged analytes into the SLM, whereas pH in the acceptor solution should be low for efficient trapping of the ana- lytes. In this manner, the basic compounds may be easily extracted into the organic phase and finally into the acceptor phase, which is directly compatible with HPLC [4]. Extraction is further promoted by strong agitation of the extraction system to reduce the stagnant boundary layer in the vicinity of the SLM and to induce convec- tion in the sample [5]. The porous hollow fiber with SLM prevents migration of salts, biological macromolecules, acids, hydrophilic compounds and neutral substances into the acceptor solution pro- viding very clean extracts [6]. In most of LPME applications, high preconcentration factor without the need for solvent evaporation and reconstitution is common, since the analytes are extracted from relatively large sample volumes into a very small volume of acceptor solution (typically 25 L) [7–9]. Although hollow fiber LPME (HF-LPME) is a very simple and effective sample preparation method, it is relatively a time-consuming technique, typically tak- ing 15–120 min [10]. In order to increase the extraction speed, an electrical potential difference is applied over the SLM as the driv- ing force. Application of voltage (150 V, DC) over a SLM has been found to enable very fast extractions from small sample volumes 0731-7085/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jpba.2010.12.006