Surfactant assisted pulsed two-phase electromembrane extraction followed by GC analysis for quantification of basic drugs in biological samples

In this work, a simple and efficient surfactant assisted pulsed two-phase electromembrane extraction (SA-PEME) procedure combined with gas chromatography (GC) has been developed for the determination of alfentanil, sufentanil and methadone in various samples. It has been found that the addition of anionic surfactant causes the accumulation of the cationic analytes at the SLM/solution interface resulting in an easier transfer of the analytes into the organic phase. The method was accomplished with 1-octanol as the acceptor phase and supported liquid membrane (SLM) by means of an 80V pulsed electrical driving force and the extraction time of 20 min. The model analytes were extracted from 3.0 mL sample solution (pH 4.0) containing 0.02% w/v surfactant (sodium dodecyl sulfate). The duty cycle of 92% and frequency of 0.357 Hz gave the best performance. Extraction recoveries in the range of 70.5-95.2% and satisfactory repeatability (7.6 < RSD < 13.7) were obtained. The limits of detection were 1.5, 1.5 and 0.6 ng mL(-1) for sufentanil, alfentanil and methadone, respectively. The method offers an acceptable linearity (2.0-1000.0 ng mL(-1)) for each analyte with coefficient of determination higher than 0.998. Furthermore, the figures of merit of SA-PEME were compared with the results from the conventional two-phase EME which confirm the advantages of the proposed technique. The method was applied for the determination and quantification of the model compounds in the wastewater, plasma, breast milk and urine samples. (C) 2015 Elsevier B.V. All rights reserved.