Determination of thebaine in water samples, biological fluids, poppy capsule, and narcotic drugs, using electromembrane extraction followed by high-performance liquid chromatography analysis

[Display omitted] ► The opium determination is of a great deal of importance from toxicological and pharmaceutical standpoints. ► Thebaine, an opium alkaloid, has been suggested as a good urinary marker of poppy capsule use. ► Electromembrane microextraction method was coupled with high performance liquid chromatography and ultraviolet detection. ► The method was developed for determination of thebaine in water, urine, poppy capsule, street heroine, and codeine tablet. ► Detection limits and intra-day precision ( n = 3) less than 15 μg L −1 and 8.9%, were obtained respectively. Opium determination is of great importance from toxicological and pharmaceutical standpoints. In present work, electromembrane extraction (EME) coupled with high-performance liquid chromatography (HPLC) and ultraviolet (UV) detection was developed for determination of thebaine as a natural alkaloid, in different matrices containing water, urine, poppy capsule, street heroine, and codeine tablet. Thebaine migrated from 3 mL of sample solutions, through a thin layer of 2-nitrophenyl octyl ether (NPOE) immobilized in the pores of a porous hollow fiber, and into a 15 μL acidic aqueous acceptor solution present inside the lumen of the fiber. The variables of interest, such as chemical composition of the organic liquid membrane, stirring speed, extraction time and voltage, pH of donor and acceptor phases and salt effect in the EME process were optimized. Under optimal conditions, thebaine was effectively extracted from different matrices with recoveries in the range of 45–55%, which corresponded to preconcentration factors in the range of 90–110. Good linearity was achieved for calibration curves with a coefficient of estimation higher than 0.997. Detection limits and intra-day precision ( n = 3) were less than 15 μg L −1 and 8.9%, respectively.