Electrically enhanced liquid-phase microextraction of three textile azo dyes from wastewater and plant samples: Sample Preparation

Synthetic azo-dye, Tartrazine induces neurodevelopmental toxicity via mitochondria-mediated apoptosis in zebrafish embryos

Tartrazine (TZ), or E 102 or C Yellow, is a commonly used azo dye in the food and dyeing industries. Its excessive usage beyond permissible levels threatens human health and the aquatic environment. While previous studies have reported adverse effects such as mutagenicity, carcinogenicity, and reproductive toxicity. Our study aimed to comprehensively evaluate the developmental neurotoxicity of TZ exposure via biochemical and behavioral examinations and explored the underlying mechanism via gene expression analyses. TZ at an environmentally relevant concentration (50 mg/L) significantly induces oxidative stress, altered antioxidant (SOD, CAT and GSH) response, triggered cellular damage (MDA and LDH), and induced neuro-biochemical changes (AChE and NO). Gene expression analyses revealed broad disruptions in genes associated with antioxidant defense (sod1, cat, and gstp1), mitochondrial dysfunction (mfn2, opa1, and fis1),evoked inflammatory response (nfkb, tnfa, and il1b), apoptosis activation (bcl2, bax, and p53), and neural development (bdnf, mbp, and syn2a). Behavioral analysis indicated altered thigmotaxis, touch response, and locomotion depending on the concentration of TZ exposure. Remarkably, the observed effective concentrations were consistent with the permitted levels in food products, highlighting the neurodevelopmental effects of TZ at environmentally relevant concentrations. These findings provide valuable insights into the underlying molecular mechanisms, particularly the role of mitochondria-mediated apoptosis, contributing to TZ-induced neurodevelopmental disorders in vivo.

Comparative Toxicity of Vegan Red, E124, and E120 Food Dyes on Three Rapidly Proliferating Model Systems

The abuse of artificial food dyes and the evidence that they harm human health recently prompted a significant effort to introduce vegan substitutes prepared from fruits and vegetables. Not much information, however, has been collected on their possible effects on aquatic and terrestrial ecosystems once released as waste in surface waters. For this purpose, we analyzed the effects of a vegan red (VEG) preparation (concentration 1.2 g/L) on three rapidly proliferating models for terrestrial and aquatic ecosystem contamination. In particular, in vitro cells cultures (exposure for 24 h), Artemia salina nauplii and Cucumis sativus seedlings (exposure 5 days). A comparison was made with the effects exerted by the two dyes that vegan red is intended to replace: an animal dye, cochineal E120 and an artificial dye E124. The analyses of conventional endpoints, indicative of cell proliferation, differentiation, and growth rate, demonstrate that the three dyes affect development and that the vegan substitute is as unsafe as the E124 and E120. Vegan red in fact impairs cell growth in in vitro cells, delays naupliar hatching and early growth in Artemia, and reduces shoot/root biomass in Cucumis. Marked hyperplasia and hypertrophy of mesophyll are also observed in Cucumis leaves. Substitution in food and beverages, therefore, should be carefully reconsidered to avoid unnecessary environmental contamination.

Commercial Red Food Dyes Preparations Modulate the Oxidative State in Three Model Organisms (Cucumis sativus, Artemia salina, and Danio rerio)

The growing environmental spreading of food synthetic dyes and bio-colors have the potential for altering organisms’ redox states. Here, three model species for aquatic pollution trials, Cucumis sativus seeds, Artemia salina cysts, and Danio rerio embryos, were short-term exposed to a fixed concentration of the artificial red E124, and two red bio-colors, cochineal E120, and vegan red (VEGR). In the animal models, we evaluated the total reactive oxygen species (ROS) and the susceptibility to in vitro oxidative stress, and in C. sativus, H2O2 production and antioxidant capacity. We also measured organismal performance indices (routine oxygen consumption in the animal models, dark oxygen consumption, and photosynthetic efficiency in C. sativus). In C. sativus, only E124 increased ROS and affected dark oxygen consumption and photosynthetic efficiency, while all dyes enhanced the antioxidant defenses. In the A. salina nauplii, all dyes increased ROS, while E120 and E124 reduced the susceptibility to oxidative stress. In D. rerio, treatments did not affect ROS content, and reduced oxidative stress susceptibility. Our data show that red food dyes affect the redox state of the developing organisms, in which ROS plays a significant role. We suggest a potentially toxic role for red food dyes with environmentally relevant consequences.

Electromembrane extraction of polar substances - Status and perspectives

In this article, the scientific literature on electromembrane extraction (EME) of polar substances (log P < 2) is reviewed. EME is an extraction technique based on electrokinetic migration of analyte ions from an aqueous sample, across an organic supported liquid membrane (SLM), and into an aqueous acceptor solution. Because extraction is based on voltage-assisted partitioning, EME is fundamentally suitable for extraction of polar and ionizable substances that are challenging in many other extraction techniques. The article provides an exhaustive overview of papers on EME of polar substances. From this, different strategies to improve the mass transfer of polar substances are reviewed and critically discussed. These strategies include different SLM chemistries, modification of supporting membranes, sorbent additives, aqueous solution chemistry, and voltage/current related strategies. Finally, the future applicability of EME for polar substances is discussed. We expect EME in the coming years to be developed towards both very selective targeted analysis, as well as untargeted analysis of polar substances in biomedical applications such as metabolomics and peptidomics.

Tartrazine exposure results in histological damage, oxidative stress, immune disorders and gut microbiota dysbiosis in juvenile crucian carp (Carassius carassius)

Tartrazine (TZ) is an azo dye widely used in foods, cosmetics, beverages, textile, and leather. In recent years, there are reports on detecting azo dyes in the aquatic environment, so the impact of these compounds on aquatic organisms could not be ignored. In this study, we aimed to evaluate the adverse effects of TZ exposure on teleosts' embryo development and juvenile's health by using crucian carp (Carassius carassius) as the experimental fish. The results showed that embryos exposed to TZ (0.19, 0.76 and 1.5 mM) exhibited a deformity, delayed egg resorption and decreased fertilization and hatching rate. When the juvenile fish were exposed to TZ at a level higher than those present in water for 30 days caused severe histopathological damages of the gill, intestine, kidney and liver. Antioxidant enzymes (CAT, SOD and GSH-Px) activities in the gill, intestine and liver, exhibited a decreasing trend after TZ exposure, while MDA contents elevated. TZ exposure also resulted in the upregulation of pro-inflammatory cytokines (il1 and il6), lysozymes (lyz), complement component 3 (c3), and β-defensin 3 (defb3). In addition, TZ exposure also affected the intestinal microbiota structure. In summary, the data in the present study indicated that TZ exposure  reduce the embryo fertilization and hatching rate; cause histopathological damage of tissues, trigger oxidative stress, innate immune disorders and dysbiosis of gut microbiota in juvenile crucian carp. Therefore, it is necessary to be informed about the hazards of TZ exposure and the discharge of the dye into waters should be strictly administrated to prevent environmental pollution.

Selective extraction and determination of Cr(VI) in food samples based on tandem electromembrane extraction followed by electrothermal atomic absorption spectrometry

In this study, electromembrane extraction (EME) combined with micro-EME (µ-EME) was used for the selective extraction of Cr(VI) from food samples (milk powder, Ocimum basilicum, and fish samples). Electrothermal atomic absorption spectrometry was used for the quantification of Cr(VI). Under the optimized extraction conditions, the extraction recovery of Cr(VI) was 73.7%. This proposed method provided a linear range from 0.01 to 5.0 ng/mL and the limit of detection (LOD) and limit of quantification (LOQ) were 0.003 and 0.010 ng/mL. The %RSD (n = 5) was in the range of 11.2-11.8% at 0.05, 1.0 and 2.5 ng/mL of Cr(VI), and the enrichment factor was 584. The accuracy of the method was evaluated by analysis of SRM 2700 as a certified reference material (CRM) and result was in good agreement with the certified value.

The electromembrane extraction of pharmaceutical compounds from animal tissues

The reliable analysis of various compounds from tissue requires a tedious sample preparation. The sample pretreatment usually involves proper homogenization that facilitates extraction of target analytes, followed by an appropriate sample clean-up preventing matrix effects. Electromembrane extraction (EME) seems to have a significant potential to streamline the whole procedure. In this study, the applicability of EME for direct isolation of analytes from animal tissues was investigated for the first time. Extraction conditions were systematically optimized to isolate model analytes (daunorubicin and its metabolite daunorubicinol) from various tissues (myocardium, skeletal muscle and liver) coming from a pharmacokinetic study in rabbits. The relative recoveries of daunorubicin and its metabolite in all tissues, determined by the UHPLC-MS/MS method, were higher than 66 and 75%, respectively. Considerably low matrix effects (0 ± 8% with CV lower than 6%) and negligible content of phospholipids detected in EME extracts demonstrate the exceptional effectiveness of this microextraction approach in purification of tissue samples. The difference in the concentrations of the analytes determined after EME and reference liquid-liquid extraction of real tissue samples was lower than 12%, which further emphasized the trustworthiness of EME. Moreover, the considerable time reduction needed for sample treatment in case of EME must be emphasized. This study proved that EME is a simple, effective and reliable microextraction technique capable of direct extraction of the analytes from pulverized tissues without the need for an additional homogenization or purification step.

Textile dyes Maxilon blue 5G and Reactive blue 203 induce acute toxicity and DNA damage during embryonic development of Danio rerio

Common textile dyes used in various industrial sectors are organic compounds and considered for the aquatic environment as pollutants. The textile dye industry is one of the main sectors that have serious impacts on the environment due to a large amount of wastewater released into the ecosystem. Maxilon blue 5G (MB-5G) and Reactive Blue 203 (RB-203) are widely used textile dyes. However, their potential toxicity on living organisms remains to be elucidated. Here, we investigate the acute toxicity and genotoxicity of MB-5G and RB-203 dyes using the zebrafish embryos/larvae. Embryos treated with each dye for 96 h revealed LC₅₀ values of acute toxicity as 166.04 mg L^-1 and 278.32 mg L^-1 for MB-5G and RB 203, respectively. When exposed to MB-5G and RB-203 at different concentrations (1, 10, and 100 mg L^-1) for 96 h, the expression of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, significantly increased in brain tissues as compared to control. MB-5G and RB-203 resulted in common developmental abnormalities including tail malformation, microphthalmia, pericardial edema, curved body axis, and yolk sac/pericardial edemas. Moreover, at its highest dose (100 mg L^-1), RB-203 caused premature hatching after 48 h, while MG-5G did not. Our results collectively reveal that the textile dyes MB-5G and RB-203 cause genotoxicity and teratogenicity during embryonic and larval development of zebrafish. Thus, it is necessary to eliminate these compounds from wastewater or reduce their concentrations to safe levels before discharging the textile industry wastewater into the environment.

Adverse effects of textile dyes on antioxidant enzymes and cholinesterase activities in Drosophila melanogaster (Oregon R+)

The effluents from textile dyeing industry are causing water pollution and may transform into more toxic and carcinogenic chemical species by environmental conditions. Therefore systemic toxicity of textile dyes is major health concern. Hence, this study sought to examine the toxic effect of disperse textile dyes on important systemic enzymes in the larvae of wild type Drosophila melanogaster (Oregon R⁺). Drosophila larvae were fed with corn-sugar-yeast diets containing two disperse dyes, Disperse blue-124 and Disperse black-9 (1, 10 and 100 mg/mL) for 2 days (48 h) and subsequent the enzymatic estimations were carried out using larval homogenate. In silico molecular docking studies were also performed to analyze the binding interaction of these dyes with acetyl choline esterase enzyme. Disperse black 9 shows more strong binding by occupying a groove and forming one hydrogen bond with Tyr465 of acetyl choline esterase enzyme while Disperse blue-124 shows surface binding without forming any hydrogen bond. Drosophila larvae fed on these dyes exhibited a dose-dependent increase in acetyl choline esterase enzymatic activity (1.8 fold increase with Disperse black-9, 100 mg/mL) while 4.4-folds Disperse blue-124, 100 mg/mL). Both Disperse Blue and Disperse Black dyes altered the activities of antioxidant enzymes Catalase (CAT, increased more than 2.5 fold), Superoxide dismutase (SOD, increased more than two folds) and showed a dose-dependent increase in Xanthine oxidase and lipid peroxidation (LPO) levels (more than 3 folds). Therefore both the disperse dyes were found to dysregulate the activities of antioxidant enzymes which may be the underlying mechanism for their toxic effects.

Herbul black henna (hair dye) causes cardiovascular defects in zebrafish (Danio rerio) embryo model

Herbul black henna (hair dye) have been widely used as cosmetic agents to temporarily change the color of hair. Their use was tremendously increased in the past decade. Especially, hair dye containing paraphenylenediamine (PPD) is extensively used globally because of its abundance and low cost. PPD, one of the main chemicals in hair dye, is known as a toxin. Hair dye has various adverse effects, including negative impacts on human health, especially during pregnancy and on aquatic environment. Although a large amount of dyes has been released into the environment, studies on environmental toxicity of these substances are still poorly understood. Hence, the main objective of this study is to evaluate the potential cardiovascular toxicological effects of hair dye on zebrafish (Danio rerio) embryo as a model. After exposing zebrafish embryos to various concentrations (100, 200, 300, 400, 500, and 600 μM), their cardiotoxicity and other teratogenic effects were examined for various exposure periods ranged from 24 to 96 hpf. As a result, the tested embryos could not survive over intervals of 48 h after 72 and 96 hpf at higher concentrations (300, 400, 500, and 600 μM), except the lower concentration cases (100 and 200 μM) some embryos were survived, respectively. However, hair dye increases mortality and decreases yolk stalk length, heart rate and severely affects heart looping in zebrafish embryos. In addition, the dye was observed to induce cardiovascular defects in transgenic Tg (fli1a:EGFP) and Tg (flk1:EGFP) zebrafish embryos at environmentally realistic dye concentrations. However, further study using bioassays is fundamentally required to predict the toxicity of hair dyes, aside from providing the information on their safe levels for living organisms. Therefore, the present results would be vital for the ecological risk assessment of hair dye, particularly for freshwater aquatic ecosystem and human health.

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.

Recent advances in microextraction procedures for determination of amphetamines in biological samples

Amphetamine and its related derivatives have stimulant and hallucinogenic properties. Illegal use of these drugs is an increasing global problem resulting in significant public health and legal problems. Deaths have been reported after intake of these drugs due to overdose. It is important to determine the type and concentration of illicit drugs in biological samples. These compounds are found in complex matrices at low concentration levels. The microextraction techniques are dominant sample preparation procedure and they are widely accepted as the most labor-intensive part of the bioanalytical process. For this purpose, a survey of recent published advances in microextraction procedures for quantification of amphetamines in biological samples found in the different databases from 2008 to date will be conducted.

Highly efficient electrochemical determination of propylthiouracil in urine samples after selective electromembrane extraction by copper nanoparticles-decorated hollow fibers

In this work, a novel, inexpensive and fast strategy was described for selective and effective extraction and determination of propylthiouracil (PTU) with a high polarity (log P = 1.2) based on electromembrane extraction (EME) followed by differential pulse voltammetry (DPV). For this purpose, copper nanoparticles (CuNPs)-decorated hollow fiber was used as the selective membrane for EME of PTU in urine samples. The influential parameters on extraction such as extraction solvent, pH, agitation speed, applied potential and extraction time were systematically investigated. In optimized conditions, acceptable linearity was attained between 0.05 and 5 µg mL^-1 (R² value = 0.9994); moreover, superb enrichment factor (200) and repeatability (RSD%, n = 4, 5.7%) for 0.1 µg mL^-1 of PTU solution were in desirable range. In addition, extraction recovery of 80.0% was achieved in this condition and the limit of detection (S/N ratio of 3:1) was 0.02 µg mL^-1. Finally, the proposed method was successfully applied to determine PTU concentration in urine samples.

Quantitation of zolpidem in biological fluids by electro-driven microextraction combined with HPLC-UV analysis

In this study, for the first time, an electro-driven microextraction method named electromembrane extraction combined with a simple high performance liquid chromatography and ultraviolet detection was developed and validated for the quantitation of zolpidem in biological samples. Parameters influencing electromembrane extraction were evaluated and optimized. The membrane consisted of 2-ethylhexanol immobilized in the pores of a hollow fiber. As a driving force, a 150 V electric field was applied to facilitate the analyte migration from the sample matrix to an acceptor solution through a supported liquid membrane. The pHs of donor and acceptor solutions were optimized to 6.0 and 2.0, respectively. The enrichment factor was obtained >75 within 15 minutes. The effect of carbon nanotubes (as solid nano-sorbents) on the membrane performance and EME efficiency was evaluated. The method was linear over the range of 10-1000 ng/mL for zolpidem (R² >0.9991) with repeatability ( %RSD) between 0.3 % and 7.3 % (n = 3). The limits of detection and quantitation were 3 and 10 ng/mL, respectively. The sensitivity of HPLC-UV for the determination of zolpidem was enhanced by electromembrane extraction. Finally, the method was employed for the quantitation of zolpidem in biological samples with relative recoveries in the range of 60-79 %.

Toxicity of dyes to zebrafish at the biochemical level: Cellular energy allocation and neurotoxicity

Dyes are widely distributed worldwide, and can be found in wastewaters resulting from industrial or urban effluents. Dyes are of particular concern as contaminants of the aquatic environment, since their toxicity remain poorly understood. Thus, the current study was designed to assess the effects induced by the synthetic azo dye Basic Red 51 (BR51) and by the natural naphthoquinone dye erythrostominone (ERY) on zebrafish early life stages (Danio rerio) at different biological organization levels, i.e., studying how changes in biochemical parameters of important physiological functions (neurotransmission and cellular energy allocation) may be associated with behavior alterations (swimming activity). This approach was also used to assess the effects of ERY after its photodegradation resulting in a colorless product(s) (DERY). Results showed that after 96 h exposure to BR51 and Ery, zebrafish embryos consumed less energy (LOEC = 7.5 mg/L), despite the unaltered levels of available energy (carbohydrates, lipids and proteins). Hence, cellular energy allocation (CEA) was significantly increased. On the other hand, only ERY decreased the acetylcholinesterase activity (LOEC = 15 mg/L). Despite that, zebrafish larvae exposed to both dyes until 144 h were less active. In contrast, DERY did not affect any parameter measured. These results indicate an association between a decrease consumption of energy and decrease swimming activity resulting from an environmental stress condition, independently of the neurotoxicity of the dyes. Degradation of ERY by light prevented all toxic effects previously observed, suggesting a cheap, fast and easy alternative treatment of effluents containing this natural dye. All tools assessed in our current study were sensitive as early-warning endpoints of dyes toxicity on zebrafish early life stages, and suggest that the CEA assay might be useful to predict effects on locomotor activity when cholinergic damage is absent.

Development of an improved sample preparation platform for acidic endogenous hormones in plant tissues using electromembrane extraction

Despite their importance in pivotal signaling pathways due to trace quantities and complex matrices, the analysis of plant hormones is a challenge. Here, to improve this issue, we present an electromembrane extraction technology combined with liquid chromatography-tandem mass spectrometry for determination of acidic plant hormones including jasmonic acid, abscisic acid, salicylic acid, benzoic acid, gibberellic acid and gibberellin A₄ in plant tissues. Factors influencing extraction efficiency, such as voltage, extraction time and stirring rate were optimized using a design of experiments. Analytical performance was evaluated in terms of specificity, linearity, limit of quantification, precision, accuracy, recovery and repeatability. The results showed good linearity (r² > 0.995), precision and acceptable accuracy. The limit of quantification ranged from 0.1 to 10 ng mL^-1, and the recoveries were 34.6-50.3%. The developed method was applied in citrus leaf samples, showing better clean-up efficiency, as well as higher sensitivity compared to a previous method using liquid-liquid extraction. Organic solvent consumption was minimized during the process, making it an appealing method. More noteworthy, electromembrane extraction has been scarcely applied to plant tissues, and this is the first time that major plant hormones were extracted using this technology, with high sensitivity and selectivity. Taken together, this work gives not only a novel sample preparation platform using an electric field for plant hormones, but also a good example of extracting complex plant tissues in a simple and effective way.

Biochemical approaches to assess oxidative stress induced by exposure to natural and synthetic dyes in early life stages in zebrafish

Zebrafish early life stages were found to be sensitive to several synthetic dyes widely used in industries. However, as environmental concentrations of such contaminants are often at sublethal levels, more sensitive methods are required to determine early-warning adverse consequences. The aim of this study was to utilize a multibiomarker approach to examine underlying oxidative stress mechanisms triggered by sublethal concentrations of synthetic azo dye Basic Red 51 (BR51), the natural dye erythrostominone (ERY), and its light-degraded product using zebrafish embryos. Biochemical biomarkers included parameters of detoxification and markers of antioxidant system, as well as oxidative damage. Results showed pro-oxidant mechanisms attributed to BR51 and ERY as evidenced by increased glutathione S-transferase (GST) activity, a phase II detoxification enzyme related to reactive oxygen species detoxification. BR51 also elevated total glutathione (GSH+GSSG) levels and catalase activity. However, both dyes induced oxidative damage as evidenced by elevated lipid peroxidation content. In contrast, when the natural dye was photodegraded, no marked effects were observed for all biomarkers assessed. Data indicate that such dyes are pro-oxidants at sublethal concentrations, predominantly involving GSH and/or related enzymes pathway.

Toxicological and behavioral responses as a tool to assess the effects of natural and synthetic dyes on zebrafish early life

Organic dyes extracted from natural sources have been widely used to develop safety and eco-friendly dyes as an alternative to synthetic ones, since the latter are usually precursors of mutagenic compounds. Thereby, toxicity tests to non-target organisms are critical step to develop harmless dyes to environment and in this context, zebrafish early life stages are becoming an important alternative model. We aimed to assess the toxic effects of the synthetic dye Basic Red 51 (BR51, used in cosmetic industry), the natural dye erythrostominone (ERY, a potential commercial dye extracted from fungi) and its photodegradation product (DERY), using zebrafish early life assays. Developmental malformations on embryos and behavioral impairment on larvae were explored. Our results showed that embryos exposed to BR51 and ERY exhibited a large yolk sac (LOEC = 7.5 mg L^-1), possibly due to a deformity or delayed resorption. ERY also induced pericardial and yolk sac edemas at high concentrations (LOEC = 15 and 30 mg L^-1, respectively). Moreover, larvae swan less distance and time when exposed to ERY (LOEC = 7.5 mg L^-1) and BR51 (LOEC = 1.875 mg L^-1). The lowest larvae locomotion have been associated with impairment of the yolk sac, important tissue of the energy source. Interestingly, DERY did not affect neither development nor behavior of zebrafish, showing that ERY photodegradation is sufficient to prevent its toxic effects. In conclusion, both natural and synthetic dyes impaired development and behavior of zebrafish early life, therefore, a simple treatment of the natural dye can prevent the aquatic life impact.

Electroextraction and electromembrane extraction: Advances in hyphenation to analytical techniques

Electroextraction (EE) and electromembrane extraction (EME) are sample preparation techniques that both require an electric field that is applied over a liquid-liquid system, which enables the migration of charged analytes. Furthermore, both techniques are often used to pre-concentrate analytes prior to analysis. In this review an overview is provided of the body of literature spanning April 2012-November 2015 concerning EE and EME, focused on hyphenation to analytical techniques. First, the theoretical aspects of concentration enhancement in EE and EME are discussed to explain extraction recovery and enrichment factor. Next, overviews are provided of the techniques based on their hyphenation to LC, GC, CE, and direct detection. These overviews cover the compounds and matrices, experimental aspects (i.e. donor volume, acceptor volume, extraction time, extraction voltage, and separation time) and the analytical aspects (i.e. limit of detection, enrichment factor, and extraction recovery). Techniques that were either hyphenated online to analytical techniques or show high potential with respect to online hyphenation are highlighted. Finally, the potential future directions of EE and EME are discussed.

Effect of type of stirring on hollow fiber liquid phase microextraction and electromembrane extraction of basic drugs: speed up extraction time and enhancement of extraction efficiency

In microextraction procedures, the stirring of the donor solution is crucial to speed up the extraction.

Electromembrane extraction--three-phase electrophoresis for future preparative applications

The purpose of this article is to discuss the principle and the future potential for electromembrane extraction (EME). EME was presented in 2006 as a totally new sample preparation technique for ionized target analytes, based on electrokinetic migration across a supported liquid membrane under the influence of an external electrical field. The principle of EME is presented, and typical performance data for EME are discussed. Most work with EME up to date has been performed with low-molecular weight pharmaceutical substances as model analytes, but the principles of EME should be developed in other directions in the future to fully explore the potential. Recent research in new directions is critically reviewed, with focus on extraction of different types of chemical and biochemical substances, new separation possibilities, new approaches, and challenges related to mass transfer and background current. The intention of this critical review is to give a flavor of EME and to stimulate into more research in the area of EME. Unlike other review articles, the current one is less comprehensive, but put more emphasis on new directions for EME.