Electromembrane extraction of verapamil and riluzole from urine and wastewater samples using a mixture of organic solvents as a supported liquid membrane: Study on electric current variations.

In this study, the application of a mixture of organic solvents as a supported liquid membrane for improving the efficiency of the electromembrane extraction procedure was investigated. The extraction process was followed by high-performance liquid chromatography analysis of two model drugs (verapamil and riluzole). In this research, four organic solvents, including 1-heptanol, 1-octanol, 2-nitrophenyl octyl ether, and 2-ethyl hexanol, were selected as model solvents and different binary mixtures (v/v 2:1, 1:1 and 1:2) were used as the supported liquid membrane. The mixture of 2-ethyl hexanol and 1-otanol (v/v, 2:1) improved the extraction efficiency of model drugs by 1.5 to 12 times. It was found that extraction efficiency is greatly influenced by the level of electric current. In this study, for various mixtures of organic solvents, the electric current fluctuated between 50 and 2500 µA, and the highest extraction efficiencies were obtained with low and stable electric currents. Finally, the optimized extraction condition was validated and applied for the determination of model drugs in urine and wastewater samples.

Inside gel electromembrane extraction: A novel green methodology for the extraction of morphine and codeine from human biological fluids.

In this work, a new mode of gel-electromembrane extraction (G-EME), called "inside" gel-EME (IG-EME) is proposed for the extraction of morphine and codeine as model basic drugs from complex biological samples. Here, an aqueous media that was captured inside the agarose gel membrane, acted as both gel membrane and the acceptor phase (AP) at the same time. In this regard, the membrane served as the separation filter (membrane) and supported liquid acceptor phase (SLAP) as well. With this new development, unwanted changes of the AP volume during the extraction, which is a common issue in the G-EME (due to electroendosmosis (EEO) phenomenon), was addressed properly. Briefly, the setup involved insertion of negative electrode inside the gel membrane and positive electrode into the donor phase (DP). Following that, the IG-EME was easily performed using optimal conditions (pH of the DP: 6.0; membrane composition (agarose concentration: 1% (w/v) in aqueous media with pH 3.0, and 15 mm thickness); voltage: 25 V; and extraction time: 30 min). After extraction, the agarose gel was withdrawn and centrifuged for 5 min with 12000 rpm, to disrupt its framework to release the "trapped aqueous AP" apart from the gel structure. The separated AP was finally injected into the HPLC-UV for the analysis. The limits of detection (LODs) and recoveries in this proposed method were obtained 1.5 ng mL-1 and 67.7 %-73.8 %, respectively. The system feasibility was examined by the quantification of model drugs in the real plasma and urine samples.

Study on electrical current variations in electromembrane extraction process: Relation between extraction recovery and magnitude of electrical current.

This contribution presents an experimental approach to improve analytical performance of electromembrane extraction (EME) procedure, which is based on the scrutiny of current pattern under different extraction conditions such as using different organic solvents as supported liquid membrane, electrical potentials, pH values of donor and acceptor phases, variable extraction times, temperatures, stirring rates, different hollow fiber lengths and the addition of salts or organic solvents to the sample matrix. In this study, four basic drugs with different polarities were extracted under different conditions with the corresponding electrical current patterns compared against extraction recoveries. The extraction process was demonstrated in terms of EME-HPLC analyses of selected basic drugs. Comparing the obtained extraction recoveries with the electrical current patterns, most cases exhibited minimum recovery and repeatability at the highest investigated magnitude of electrical current. . It was further found that identical current patterns are associated with repeated extraction efficiencies. In other words, the pattern should be repeated for a successful extraction. The results showed completely different electrical currents under different extraction conditions, so that all variable parameters have contributions into the electrical current pattern. Finally, the current patterns of extractions from wastewater, plasma and urine samples were demonstrated. The results indicated an increase in the electrical current when extracting from complex matrices; this was seen to decrease the extraction efficiency.