Conventional Electromembrane Extraction Research Articles

Gel-electromembrane extraction of peptides: Determination of five hypothalamic agents in human plasma samples

Agarose gel as a green membrane has been proposed for use in electromembrane extraction of five hypothalamic-related peptides without an ionic carrier. Octreotide, goserelin, triptorelin, cetrorelix, and somatostatin were extracted from 5.0 mL of sample solution (adjusted to pH 5.0) into a microvolume acceptor solution (HCl, 100 mM) under the applied voltage of 30 V in 15 min. The pH of the agarose gel 3.0% (w/v) was adjusted to 4.0 to facilitate the movement of peptides through the membrane. Quantification was performed using an HPLC-UV system on a C18 column. Quantification and detection limits were found to be in the range of 15.0–20.0 ng mL−1 and 4.5–6.0 ng mL−1, respectively. Dynamic linear ranges were found to be in the range of 15.0–1000 ng mL−1 (R2 > 0.995) and recoveries were in the range of 62.3–77.6%. The optimized method was applied to spiked human plasma samples. The method showed relative recoveries in the range of 44.8–66.0%. Finally, the proposed method was compared with and shown to have higher recoveries than, the conventional electromembrane extraction method for the peptides under study.

Sugaring-out assisted electromembrane extraction of basic drugs from biological fluids: Improving the efficiency and stability of extraction system

In the current study, for the first time, the sugaring-out effect was assessed in a conventional electromembrane extraction (EME) system. Utilizing the sugars in the donor solution as green additives can result in production of a pioneering and influential EME mode. Sugaring-out assisted electromembrane extraction was combined with high-performance liquid chromatography (HPLC) to enhance the extraction of four basic model drugs (pseudoephedrine, lidocaine, propranolol, and ketoconazole). In this mode of EME, not only the transfer of analytes through the supported liquid membrane (SLM) was improved, but also the whole extraction system became more stable than the conventional one in the same voltage. The type and concentration of sugars were optimized in addition to the common experimental parameters influencing the EME, and figures of merit were also studied. Under the optimum conditions, repeatability (RSD%) was obtained in the range of 2.8–6.9% in the water, while RSD value was obtained in the range of 8.2–11.8% (n = 3) for conventional EME with the same state. The linearity range was also in the interval of 5.0–1000.0 ng mL-1 and limits of quantification and detection were in the ranges of 5.0–10.0 ng mL-1 and 1.5–3.0 ng mL-1, respectively, in the introduced EME. Extraction recoveries in the range of 41.2 and 80.8% were obtained resulting in enrichment factors in the range of 96–189. In light of such factor, new suggested EME mode was assessed in the real biological samples including human plasma and urine in order to prove the sugaring-out efficiency in EME systems.

Development and application of SBA‐15 assisted electromembrane extraction followed by corona discharge ion mobility spectrometry for the determination of Thiabendazole in fruit juice samples

A new sample preparation method based on SBA-15 assisted electromembrane extraction coupled with corona discharge ion mobility spectrometer was developed for the determination of Thiabendazole as a model basic pesticide in fruit juice samples. The addition of SBA-15 in the supported liquid membrane in electromembrane extraction system not only can lead to enhancement of the effective surface area, but also introducing the negatively charged silanol groups into supported liquid membrane might improve migration of positively charged analytes toward the supported liquid membrane and finally into the acceptor solution. To investigate the effect of the presence of SBA-15 in the supported liquid membrane on the extraction efficiency, a comparative study was carried out between the conventional electromembrane extraction and SBA-15/electromembrane extraction methods. Under the optimized conditions, SBA-15/electromembrane extraction method showed higher extraction efficiencies in comparison with conventional electromembrane extraction method. SBA-15/electromembrane extraction method exhibited a low limit of detection (0.9ng/mL), high preconcentration factor (167) and high recovery (83%). Finally, the applicability of SBA-15/electromembrane extraction method was studied by the extraction and determination of Thiabendazole as a model basic pesticide in fruit juice samples.

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.

Electro-driven extraction of polar compounds using agarose gel as a new membrane: Determination of amino acids in fruit juice and human plasma samples

In this work, polypropylene hollow fiber was replaced by agarose gel in conventional electro membrane extraction (EME) to develop a novel approach. The proposed EME method was then employed to extract two amino acids (tyrosine and phenylalanine) as model polar analytes, followed by HPLC-UV. The method showed acceptable results under optimized conditions. This green methodology outperformed conventional EME, and required neither organic solvents nor carriers. The effective parameters such as the pH values of the acceptor and the donor solutions, the thickness and pH of the gel, the extraction voltage, the stirring rate, and the extraction time were optimized. Under the optimized conditions (acceptor solution pH: 1.5; donor solution pH: 2.5; agarose gel thickness: 7mm; agarose gel pH: 1.5; stirring rate of the sample solution: 1000rpm; extraction potential: 40V; and extraction time: 15min), the limits of detection and quantification were 7.5ngmL−1 and 25ngmL−1, respectively. The extraction recoveries were between 56.6% and 85.0%, and the calibration curves were linear with correlation coefficients above 0.996 over a concentration range of 25.0–1000.0ngmL−1 for both amino acids. The intra- and inter-day precisions were in the range of 5.5–12.5%, and relative errors were smaller than 12.0%. Finally, the optimized method was successfully applied to preconcentrate, clean up, and quantify amino acids in watermelon and grapefruit juices as well as a plasma sample, and acceptable relative recoveries in the range of 53.9–84.0% were obtained.

Simultaneous electromembrane extraction of cationic and anionic herbicides across hollow polymer inclusion membranes with a bubbleless electrode

A new electric-field driven extraction approach based on the integration of a bubbleless electrode into the electromembrane extraction (EME) across hollow polymer inclusion membranes (HPIMs) was demonstrated for the first time. The bubbleless electrode was prepared based on an in-situ synthesised polyacrylamide within a fused silica capillary. The electrode functions as a salt bridge, which conducts the electrical current between the acceptor phase in the lumen of the HPIM and the acceptor solution in the reservoir connected to a high voltage supply through a platinum electrode. Two types of HPIMs were employed, which consisted of desired proportions of cellulose acetate as base polymer, tris(2-ethylhexyl)phosphate as plasticizer, and di-(2-ethylhexyl)phosphoric acid as anionic carrier or Aliquat 336 as cationic carrier, respectively. The EME strategy was evaluated for the simultaneous determination of cationic quaternary ammonium and anionic chlorophenoxy acetic acid herbicides present in the river water, respectively. The analysis was carried out using capillary electrophoresis coupled with UV and contactless conductivity detection. Under the optimised conditions, enrichment factors in the range of 152–185-fold were obtained from 4mL of river water sample with a 20min extraction time and an applied voltage of 3000V. The proposed method provided good linearity with correlation coefficients ranging from 0.9982 to 0.9997 over a concentration range of 1–1000μg/L. The detection limits of the method for the herbicides were in the range of 0.3–0.4μg/L, with relative standard deviations of between 4.8% and 8.5%. The relative recoveries obtained when analysing the spiked river water ranged from 99.1% to 100%. A comparison was also made between the newly developed approach with the conventional EME setup by placing the platinum electrode directly in the lumen of the HPIMs.

Introduction of Fullerene as a New Carrier in Electromembrane Extraction for the Determination of Ibuprofen and Sodium Diclofenac as Model Acidic Drugs in Real Urine Samples

Introducing new additives in supported liquid membrane (SLM) as carriers is an interesting and debatable issue in the field of microextraction methods, especially in electro membrane extraction (EME). In this study, C60 fullerene was used as a new carrier in the SLM, and EME followed by high-performance liquid chromatography coupled with ultraviolet detection was optimized and validated for the quantification of ibuprofen and sodium diclofenac as two model acidic drugs. Optimized conditions for extraction of the mentioned drugs from 4.0 mL aqueous sample were obtained as follows: 1-octanol containing 0.6% (w/v) C60 fullerene as the SLM, potential difference of 6 V, 28 min as the extraction time, 12.8 as the acceptor phase pH value and 10.5 as the donor phase pH value. Under the optimized conditions, the enrichment factors were obtained within the range of 166–188, which corresponds to extraction recoveries of 83–94%. The limits of detection and quantification were in the range of 5–10 and 15–30 ng mL−1, respectively. To understand the influence of C60 fullerene on extraction efficiency, a comparative study was carried out between conventional EME and modified EME methods. The results showed that the presence of C60 fullerene in the SLM increased the overall analyte partition coefficient in the membrane and, therefore, led to an enhancement in analyte transport. Finally, the applicability of this method was evaluated by the extraction and determination of these drugs in real urine samples.

Introduction of high nitrogen doped graphene as a new cationic carrier in electromembrane extraction.

This paper proposes for the first time, the use of high nitrogen doped graphene (HND-G) as a new cationic carrier for the enhancement of electromembrane extraction (EME) performance. Sensitivity of EME was improved by the modification of supported liquid membrane composition through the addition of HND-G into 1-octanol for the extraction of naproxen and sodium diclofenac as model acidic drugs. The comparison between HND-G-modified EME and conventional EME showed that HND-G could increase the overall partition coefficient of acidic drugs in the membrane due to the fact that HND-G acts as an ion pair reagent and there is an electrostatic interaction between positively charged HND-G and acidic drugs with negative charge. During the extraction, model acidic drugs migrated from a 10 mL aqueous sample solution (pH 9.6) through a thin layer of 1-octanol containing 0.6% w/v of HND-G that was impregnated in the pores of a hollow fiber, into a 30 μL basic aqueous acceptor solution (pH 12.3) present in the lumen of the hollow fiber. Equilibrium extraction conditions were obtained after 16 min of operation with the whole assembly agitated at 1000 rpm. Under the optimized conditions, the enrichment factors were between 238 and 322 and also the LODs ranged from 0.1 to 0.7 ng/mL in different samples. Finally, the applicability of this method was evaluated by the extraction and determination of drugs of interest in real urine samples.

Electromembrane extraction through a virtually rotating supported liquid membrane.

Electromembrane extraction (EME) of model analytes was carried out using a virtually rotating supported liquid membrane (SLM). The virtual (nonmechanical) rotating of the SLM was achieved using a novel electrode assembly including a central electrode immersed inside the lumen of the SLM and five counter electrodes surrounding the SLM. A particular electronic circuit was designed to distribute the potential among five counter electrodes in a rotating pattern. The effect of the experimental parameters on the recovery of the extraction was investigated for verapamil (VPL), trimipramine (TRP), and clomipramine (CLP) as the model analytes and 2-ethyl hexanol as the SLM solvent. The results showed that the recovery of the extraction is a function of the angular velocity of the virtual rotation. The best results were obtained at an angular velocity of 1.83 RadS(-1) (or a rotation frequency of 0.29 Hz).The optimization of the parameters gave higher recoveries up to 50% greater than those of a conventional EME method. The rotating also allowed the extraction to be carried out at shorter time (15 min) and lower voltage (200 V) with respect to the conventional extraction. The model analytes were successfully extracted from wastewater and human urine samples with recoveries ranging from 38 to 85%. The RSD of the determinations was in the range of 12.6 to 14.8%.

One-way and two-way pulsed electromembrane extraction for trace analysis of amino acids in foods and biological samples

In the present work, pulsed electromembrane extraction (PEME) was performed for the first time, as a new concept of electrically enhanced microextraction method, for extraction and quantification of histidine, phenylalanine and tryptophan in different matrices. PEME offers an alternative to conventional electromembrane extraction (EME), which faces problems such as serious instabilities in the analysis of real samples with high concentration levels of ions. In these samples, increasing of the ion transportation across the liquid membrane results in Joule heating during the extraction process which may follow by punctuation of the organic membrane, increasing of the current level and bubble formation due to electrolysis reactions. A mixture of 2-nitrophenyl octyl ether (NPOE), di-(2-ethylhexyl) phosphate (DEHP) and tris-(2-ethylhexyl) phosphate (TEHP) was immobilized in the pores of hollow fiber as the organic liquid membrane. Other effective parameters such as extraction time, ion balance and pulse frequency were optimized using the experimental design. Extraction recoveries in the range of 7.1–21.6% and satisfactory repeatability (2.1<CV%<4.5) were obtained. Limits of detection were 5, 10 and 30ngmL−1 for tryptophan, phenylalanine and histidine, respectively. The method offers acceptable linearity with correlation coefficients higher than 0.9979. Furthermore, the figures of merit of PEME are compared with the results from conventional electromembrane extraction (EME), which proves the advantages of the proposed technique. The method was applied to the determination and quantification of amino acids in foods and biological samples. Also, two-way PEME was employed as a novel approach for highly selective extraction of tryptophan as a model analyte to introduce an interesting ability of the proposed technique.

A new method for the enhancement of electromembrane extraction efficiency using carbon nanotube reinforced hollow fiber for the determination of acidic drugs in spiked plasma, urine, breast milk and wastewater samples

A new design of low voltage electromembrane extraction (EME) using carbon nanotube reinforced hollow fiber was developed for the determination of acidic drugs in biological and wastewater samples. The supported liquid membrane (SLM) with carbon nanotubes as the sorbent interface was used in this research. CNTs have large surface area and high adsorption capacity for a wide range of organic and inorganic species. Therefore, the presence of CNTs in SLM increased the overall analyte partition coefficient in the membrane and lead to enhancement in analyte transport. Optimization of the variables affecting this method was carried out in order to achieve the best extraction efficiency. Ibuprofen and naproxen, nonsteroid anti-inflammatory drugs (NSAIDs), were selected as model acidic drugs. Optimal extractions were accomplished with 1-octanol with 3.0mgmL−1 CNTs as the SLM, with 5V as the driving force, and with pH 7.4 in donor and pH 12 in acceptor solutions. Equilibrium extraction conditions were obtained after 10min of operation with the whole assembly agitated at 500rpm. Under the optimized extraction conditions, the proposed EME technique provided good linearity (>0.998), repeatability (RSD=2.7–3.2), low limits of detection (1–3ngmL−1), excellent preconcentration (PF=180–188) and high recoveries (90–94%). In comparison with the conventional EME method, this method showed better results (lower voltage, higher preconcentration factors and higher recoveries). Finally, the developed method was successfully used for the determination of ibuprofen and naproxen in different spiked matrices including plasma, urine, breast milk and wastewater samples.

Pulsed electromembrane extraction: A new concept of electrically enhanced extraction

In the present work, pulsed electromembrane extraction (PEME) is introduced for the first time as an efficient and inexpensive method for the extraction of ionizable compounds from different matrices. The setup proposed for electromembrane extraction (EME) provides a very stable system and satisfactory repeatability (RSDs<4.4) in comparison with existing methods. In this paper, PEME is conducted for the extraction of model analytes from biological fluids. The effective parameters such as extraction time, applied voltage and the duration of pulse and outage period are optimized using the experimental design. Preconcentration factors in the range of 100–140 and recoveries in the range of 95–108 were obtained in different biological matrices. The linear dynamic ranges of 5–200ngmL−1 (with correlation coefficient higher than 0.9955) and limits of detection of 1.0ngmL−1 were obtained for both of the drugs. The figures of merit of PEME were compared with the results from conventional EME, which proves the advantages of the proposed technique.