Electromembrane extraction-Recent trends and where to go

Developing a miniaturized setup for in-tube simultaneous determination of three alkaloids using electromembrane extraction in combination with ultraviolet spectrophotometry

Herein, electromembrane extraction was combined with ultraviolet spectrophotometry using a customized manifold for preconcentration and simultaneous determination of morphine, codeine, and papaverine in water and human urine samples. Absorption spectra of the extracts were recorded inside the lumen of the hollow fiber using two fiber optics connected to a miniature spectrophotometer. Partial least squares regression was applied to resolve the overlapped spectra of the analytes. Performance of the model was validated by an independent test set. Central composite design was applied to optimize the extraction parameters. The optimized extraction conditions are as follows; supporting liquid membrane: 2-nitrophenyl octyl ether containing 15% v/v bis(2-ethylhexyl) phosphate, applied voltage: 80 V, donor pH: 3.0, acceptor pH: 1.0, extraction time: 20 min. Finally, the optimized extraction method was validated for determination of the mentioned alkaloids in human urine samples. The method showed good linearity (R²  > 0.995) for all of the mentioned alkaloids. The limits of detection for morphine, codeine, and papaverine in diluted human urine were found to be 0.6, 1.1, and 0.6 ng/mL, respectively with acceptable relative standard deviations. Enrichment factors of 104, 108, and 102 were achieved for morphine, codeine, and papaverine, respectively.

On-chip electromembrane extraction of acidic drugs

In the present work, a new supported liquid membrane (SLM) has been developed for on-chip electromembrane extraction of acidic drugs combined with HPLC or CE, providing significantly higher stability than those reported up to date. The target analytes are five widely used non-steroidal anti-inflammatory drugs (NSAIDs): ibuprofen (IBU), diclofenac (DIC), naproxen (NAX), ketoprofen (KTP) and salicylic acid (SAL). Two different microchip devices were used, both consisted basically of two poly(methyl methacrylate) (PMMA) plates with individual channels for acceptor and sample solutions, respectively, and a 25 µm thick porous polypropylene membrane impregnated with the organic solvent in between. The SLM consisting of a mixture of 1-undecanol and 2-nitrophenyl octyl ether (NPOE) in a ratio 1:3 was found to be the most suitable liquid membrane for the extraction of these acidic drugs under dynamic conditions. It showed a long-term stability of at least 8 hours, a low system current around 20 µA, and recoveries over 94% for the target analytes. NPOE was included in the SLM to significantly decrease the extraction current compared to pure 1-undecanol, while the extraction properties was almost unaffected. Moreover, it has been successfully applied to the determination of the target analytes in human urine samples, providing high extraction efficiency.

Electromembrane extraction with solvent modification of the acceptor solution: improved mass transfer of drugs of abuse from human plasma

Aim: Electromembrane extraction (EME) of 37 drugs of abuse with significant differences in terms of polarity (0.68 < log P < 4.3) and basicity (1.17 < pKa < 10.38) was investigated from human plasma. Materials & methods: EME was performed with 250 mM trifluoroacetic acid and DMSO (1:1 v/v) in the acceptor solution. Results & conclusion: The analytes were extracted efficiently with pure 2-nitrophenyloctyl ether as supported liquid membrane when the acceptor solution was modified with DMSO. Thus, using DMSO mixed with 250 mM trifluoroacetic acid (1:1, v/v) as acceptor solution, recoveries from 40 to 105% (relative standard deviation <20%) were obtained for 33 of the analytes under optimized conditions. EME followed by ultra-HPLC–MS/MS analysis was evaluated from human plasma, and the results were satisfactory.

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.

Recovery of Anthocyanins Using Membrane Technologies: A Review

Anthocyanins are naturally occurring polyphenolic compounds and give many flowers, fruits and vegetable their orange, red, purple and blue colors. Besides their color attributes, anthocyanins have received much attention in recent years due to the growing evidence of their antioxidant capacity and health benefits on humans. However, these compounds usually occur in low concentrations in mixtures of complex matrices, and therefore large-scale harvesting is needed to obtain sufficient amounts for their practical usage. Effective fractionation or separation technologies are therefore essential for the screening and production of these bioactive compounds. In this context, membrane technologies have become popular due to their operational simplicity, the capacity to achieve good simultaneous separation/pre-concentration and matrix reduction with lower temperature and lower operating cost in comparison to other sample preparation methods. Membrane fractionation is based on the molecular or particle sizes (pressure-driven processes), on their charge (electrically driven processes) or are dependent on both size and charge. Other non-pressure-driven membrane processes (osmotic pressure and vapor pressure-driven) have been developed in recent years and employed as alternatives for the separation or fractionation of bioactive compounds at ambient conditions without product deterioration. These technologies are applied either individually or in combination as an integrated membrane system to meet the different requirements for the separation of bioactive compounds. The first section of this review examines the basic principles of membrane processes, including the different types of membranes, their structure, morphology and geometry. The most frequently used techniques are also discussed. Last, the specific application of these technologies for the separation, purification and concentration of phenolic compounds, with special emphasis on anthocyanins, are also provided.

Application of polyacrylamide gel as a new membrane in electromembrane extraction for the quantification of basic drugs in breast milk and wastewater samples

Introducing new membranes with green chemistry approach seems to be a great challenge for the development of a practical method in separation science. In this regard, for the first time, polyacrylamide gel as a new membrane in electromembrane extraction (EME) was used for the extraction of three model basic drugs (pseudoephedrine (PSE), lidocaine (LID), and propranolol (PRO)), followed by HPLC-UV. In comparison with conventional EME, in this method neither organic solvent nor carrier agents were used for extraction of mentioned drugs. Different variables for fabrication of polyacrylamide gel and extraction process were evaluated. Polyacrylamide gel (containing 12% (w/v) acrylamide, and 3.0% (w/w) bisacrylamide) with 2 mm thickness at pH = 1.5 was fabricated as membrane. The drugs were extracted from aqueous samples, through a polyacrylamide gel membrane, to an aqueous acceptor phase on membrane. Under the optimized extraction conditions (Voltage: 85 V, extraction time: 28 min, acceptor phase's pH: 4.0, and donor phase's pH: 7.0) limits of quantification and detection were in the ranges of 1.0-20.0 ng mL^-1 and 0.3-6.0 ng mL^-1, respectively. Applying the proposed method to determine and quantify intended drugs in breast milk, and wastewater samples have revealed acceptable results.