Electro membrane extraction combined with capillary electrophoresis for the determination of amlodipine enantiomers in biological samples

Dextrin-assisted gel electromembrane extraction of chiral drugs: Improving the extraction efficiency and investigation of enantioselectivity of extraction

The present study investigates the use of dextrins (maltodextrin, β-cyclodextrin, and hydroxypropyl-β-cyclodextrin) to improve the efficiency of the agarose-based gel electromembrane extraction technique for extracting chiral basic drugs (citalopram, hydroxyzine, and cetirizine). Additionally, it examines the enantioselectivity of the extraction process for these drugs. To achieve these, dextrins were incorporated into either the sample solution, the membrane, or the acceptor solution, and then the extraction procedure was performed. Enantiomers were separated and analyzed using a capillary electrophoresis device equipped with a UV detector. The results obtained under the optimal extraction conditions (sample solution pH: 4.0, acceptor solution pH: 2.0, gel membrane pH: 3.0, agarose concentration: 3 % w/v, stirring rate: 1000 rpm, gel thickness: 4.4 mm, extraction voltage: 62.3 V, and extraction time: 32.1 min) indicated that incorporating dextrins into either the sample solution, membrane or the acceptor solution enhances extraction efficiency by 17.3-23.1 %. The most significant increase was observed when hydroxypropyl-β-cyclodextrin was added to the acceptor solution. The findings indicated that the inclusion of hydroxypropyl-β-cyclodextrin in the sample solution resulted in an enantioselective extraction, yielding an enantiomeric excess of 6.42-7.14 %. The proposed method showed a linear range of 5.0-2000 ng/mL for enantiomers of model drugs. The limit of detection and limit of quantification for all enantiomers were found to be < 4.5 ng/mL and <15.0 ng/mL, respectively. Intra- and inter-day RSDs (n = 4) were less than 10.8 %, and the relative errors were less than 3.2 % for all the enantiomers. Finally, the developed method was successfully applied to determine concentrations of enantiomers in a urine sample with relative recoveries of 96.8-99.2 %, indicating good reliability of the developed method.

Liquid-Phase Microextraction Approaches for Preconcentration and Analysis of Chiral Compounds: A Review on Current Advances

Chirality is a critical issue in pharmaceutics, forensic chemistry, therapeutic drug monitoring, doping control, toxicology, or environmental investigations as enantiomers of a chiral compound can exhibit different activities, i.e., one enantiomer can have the desired effect while the other one can be inactive or even toxic. To monitor enantioselective metabolism or toxicokinetic/toxicodynamic mechanisms in extremely low content in biological or environmental matrices, sample preparation is vital. The present review describes current status of development of liquid-phase microextraction approaches such as hollow fiber liquid-phase microextraction (HF-LPME), electromembrane extraction (EME), dispersive liquid-liquid microextraction (DLLME), and supramolecular solvent-based microextraction (SSME), used for sample preparation of enantiomers/chiral compounds. The advantages and limitations of the above techniques are discussed. Attention is also focused on chiral separation approaches commonly applied to study the stereo-selective metabolism or toxicokinetic/toxicodynamic mechanisms of enantiomers in the biological and environmental samples.

Sensitivity enhancement in capillary electrophoresis and their applications for analyses of pharmaceutical and related biochemical substances

This review aims to illustrate sensitivity enhancement methods in capillary electrophoresis (CE) and their applications for pharmaceutical and related biochemical substance analyses. The first two parts of the article describe the introduction and principle of CE. The main part focuses on strategies for sensitivity improvement in CE including detector and capillary technologies and pre-concentration techniques. Applications of these techniques for pharmaceutical and biomedical substance analyses are surveyed during the years 2018-2021. This article is protected by copyright. All rights reserved.

Development of electrically assisted solvent bar microextraction followed by high performance liquid chromatography for the extraction and quantification of basic drugs in biological samples

In this study, a new extraction procedure is introduced based on electrically assisted solvent bar microextraction. In the first step, the analytes are transferred from sample solution to the hollow fiber supported organic solvent. After that, with the aid of an electrical field, the analytes migrated into the aqueous extractant. The proposed approach was used to extract the three basic drugs (including lidocaine, diltiazem, and propranolol) from the plasma and urine samples. Under the optimized condition, (the supported organic solvent: 1-octanol, stirring rate: 300 rpm, pH of sample solution: 12.0, salt concentration: 2.0% (w/v), extraction time: 15 min, aqueous extractant: (30 µL, 100 mM HCl), back-extraction time: 2 min, back-extraction voltage: 100 V), the proposed procedure presented wide linearities with coefficients of determination more than 0.992 over a concentration range of 5.0-1000 ng mL^-1. The limit of detection was also determined in the range of 0.5 to 5.0 ng mL^-1, repeatability (intra-day) was between 3.3 and 11.1% (n = 4), and reproducibility (inter-day) was between 4.3 and 14.6% (n = 4 days). It was indicated that the proposed approach could effectively extract the analytes from the plasma and urine samples, and the relative recoveries were between 90.2 and 105.6%, indicating the validity of this method.

Analytical and Bioanalytical Techniques for the Quantification of the Calcium Channel Blocker - Amlodipine: A Critical Review

Hypertension is a condition in which blood pressure is elevated to an extent where benefit is obtained from blood pressure lowering. The risk of complications is proportional to the level that blood pressure raises. Calcium channel blockers are a class of compounds used in the treatment of hypertension. The dihydropyridine (DHP) group, a subclass of the calcium channel blocker works almost exclusively on L-type calcium channels in the peripheral arterioles and reduce blood pressure by reducing total peripheral resistant. Long acting DHP is preferred because they are more convenient for patients and avoid the large fluctuations in plasma drug concentration which are associated with side effects. Amlodipine is the most distinct DHP and the most popular. The drug was patented in the year 1986 and its commercial sale began by 1990. The current article provides a state of art about the analytical and bioanalytical techniques available for the quantification of drug as a single entity and in combined pharmaceutical formulations between 1989 and 2019.

Electromembrane Extraction Using Sacrificial Electrodes

In this paper, we report the first example of employing a sacrificial electrode in the acceptor solution during electromembrane extraction (EME). The electrode was based on a silver wire with a layer of silver chloride electroplated onto the surface. During EME, the electrode effectively inhibited electrolysis of water in the acceptor compartment, by accepting the charge transfer across the SLM, which enabled the application of 500 μA current without suffering gas formation or pH changes from electrolysis of water. The electroplating strategy was optimized with a design-of-experiments (DOE) methodology that provided optimal conditions of electroplating. With an optimized electrode, 1 cm of the electrode in contact with the acceptor solution inhibited electrolysis of water for approximately 30 min at 500 μA current (redox capacity). Further, the redox capacity of the electrode was found to increase through multiple uses. The advantage of the electrode was demonstrated by extracting polar analytes at high-current conditions in a standard EME system comprising 2-nitrophenyl octyl ether (NPOE) as SLM and 10 mM HCl as sample/acceptor solutions. Application of high current enabled significantly higher recoveries than could otherwise be obtained at 100 μA. Sacrificial electrodes were also tested in μ-EME and were found beneficial by eliminating detrimental bubble formation. Thus, the sacrificial electrodes improved the stability of μ-EME systems. The findings of this paper are important for development of stable and robust systems for EME operated at high voltage/current and for EME performed in narrow channels/tubing where bubble formation is critical.

Electromembrane extraction of substances with weakly basic properties: a fundamental study with benzodiazepines

Aim: Electromembrane extraction (EME) of weakly basic benzodiazepines was investigated (-1.47 < pKa < 5.01). Materials & Methods: 96-well EME was performed with strongly acidic conditions in the acceptor solution using 250-mM trifluoroacetic acid to maximize ionization. Results & Conclusion: Recoveries more than 80% were obtained for analytes with pKa > 2, whereas EME was less efficient for substances with pKa < 2. The latter was trapped in the supported liquid membrane due to less acidic pH conditions in the acceptor solution close to the supported liquid membrane. EME followed by UHPLC–MS/MS analysis was evaluated from human plasma, and the results were in compliance with EMA guidelines. Both electrokinetic migration and passive diffusion contributed to mass transfer when performing EME of weakly basic analytes.

Efficient discrimination and removal of phospholipids during electromembrane extraction from human plasma samples

Aim: For the first time, extracts obtained from human plasma samples by electromembrane extraction (EME) were investigated comprehensively with particular respect to phospholipids using ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS). Thhe purpose was to investigate the potential of EME for phospholipid cleanup in different EME systems. Results & discussion: No traces of phospholipids were detected in any of the acceptor solutions, whereas the model analytes were extracted with recoveries up to 50%. Thus, the EME systems tested in this work were found to be highly efficient for providing phospholipid-free extracts. Conclusion: Ultra-HPLC–MS/MS analysis of the donor solutions revealed that the phospholipids principally remained in the plasma samples. This proved that the phospholipids did not migrate in the electrical field and they were prevented from penetrating the supported liquid membrane.

Efficient design for in situ determination of amlodipine in whole blood samples using fast Fourier transform stripping square wave voltammetry after preconcentration by electromembrane extraction

Ultra-sensitive in situ determination of amlodipine in whole blood samples was conducted using FFT voltammetry after preconcentration by electromembrane extraction.

The potential of electromembrane extraction for bioanalytical applications

Modern requirements in the field of bioanalysis often involve miniaturized, high-throughput sample preparation techniques that consume low amounts of both sample and potentially hazardous organic solvents. Electromembrane extraction is one technique that meets several of these requirements. In this principle analytes are selectively extracted from a biological matrix, through a supported liquid membrane and into an aqueous acceptor solution. The whole extraction process is facilitated by an electric field across the supported liquid membrane, which greatly reduces the extraction time. This review will give a thorough overview of recent advances in bioanalytical applications involving electromembrane extraction, and discuss both possibilities and challenges of the technique in a bioanalytical setting.

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.

Electrical field-induced extraction and separation techniques: promising trends in analytical chemistry--a review

Sample preparation is an important issue in analytical chemistry, and is often a bottleneck in chemical analysis. So, the major incentive for the recent research has been to attain faster, simpler, less expensive, and more environmentally friendly sample preparation methods. The use of auxiliary energies, such as heat, ultrasound, and microwave, is one of the strategies that have been employed in sample preparation to reach the above purposes. Application of electrical driving force is the current state-of-the-art, which presents new possibilities for simplifying and shortening the sample preparation process as well as enhancing its selectivity. The electrical driving force has scarcely been utilized in comparison with other auxiliary energies. In this review, the different roles of electrical driving force (as a powerful auxiliary energy) in various extraction techniques, including liquid-, solid-, and membrane-based methods, have been taken into consideration. Also, the references have been made available, relevant to the developments in separation techniques and Lab-on-a-Chip (LOC) systems. All aspects of electrical driving force in extraction and separation methods are too specific to be treated in this contribution. However, the main aim of this review is to provide a brief knowledge about the different fields of analytical chemistry, with an emphasis on the latest efforts put into the electrically assisted membrane-based sample preparation systems. The advantages and disadvantages of these approaches as well as the new achievements in these areas have been discussed, which might be helpful for further progress in the future.