This review highlights applications of online sample preconcentration techniques in capillary electrophoresis (CE) analyses of enantiomers from 1995 to 2025. Various preconcentration techniques based on the analyte velocity change in two or three discontinuous solution system, including field-amplified sample stacking, sweeping, transient isotachophoresis, pH-mediated stacking, and their modified and combined techniques, have been employed to enrich and separate optical isomers in CE. More than 50 published research articles retrieved from Google Scholar databases from the years 1995 to 2025 described the application of dynamic online sample preconcentration techniques to chiral CE analyses. This review provides comprehensive tables listing the applications of the online sample preconcentration techniques in chiral CE.
Molecularly imprinted polymers (MIPs) have gained increasing attention as synthetic recognition materials that mimic biological binding sites while offering greater stability and lower cost. In recent years, their combination with electrophoretic techniques has opened new possibilities for improving selectivity and sensitivity in drug analysis. This review summarizes the fundamental concepts behind MIP formation, including template-monomer interactions, imprinting strategies, and common polymerization approaches such as bulk, surface, and nano-imprinting. The integration of MIPs with capillary electrophoresis (CE), capillary electrochromatography, and microfluidic platforms is critically discussed, with particular emphasis on how these hybrid systems enhance separation performance and analytical reliability. Their applications are highlighted across pharmaceutical quality control, clinical drug monitoring, forensic toxicology, and environmental residue detection. Recent progress in nanostructured MIPs and lab-on-a-chip systems is also covered, showing improved binding kinetics and potential for miniaturized analysis. Despite these advances, challenges such as template leakage, reproducibility issues, and matrix effects still limit wider adoption. Overall, this review emphasizes the growing role of MIP-electrophoresis platforms as promising tools for next-generation drug analysis.
The electrical characteristics of biological cells offer a powerful, label-free modality for investigating cellular morphology and phenotype, monitoring drug effects, and enabling selective manipulation and sorting strategies. Fundamental properties-including permittivity, conductivity, membrane capacitance, polarizability, and surface charge-dictate cellular responses to external electric fields, providing deep insights into cellular structure, physiology, and population heterogeneity. This review examines the recent literature on cell electrophysiology and highlights how innovations in utilizing cellular electrical signatures drive a diverse range of critical applications. Emphasis is given to the latest advances in the analysis of prokaryotic and eukaryotic systems across medical, clinical, environmental, and industrial contexts. This work aims to provide a comprehensive overview of relevant recent reports and novel platforms, where electrokinetic methodologies have been successfully applied to enable rapid cellular assessments, illustrating the potential for applying cellular electrical signatures across numerous scientific disciplines, including clinical diagnosis, drug development, personalized medicine, and industrial bioprocessing.
Synthetic cannabinoids (SCs) belong to one of the fastest-growing classes of new psychoactive substances nowadays. Among users, they can be sprayed onto herbal incense or paper or used as E-liquids. As many of them are still legal, they can be purchased on the internet very easily. Their continuous appearance on the illicit drug market and structural variability poses significant challenges for their analysis and detection. Moreover, some of them are chiral and could be distributed either as pure enantiomers or racemates. Sub/supercritical fluid chromatography (SFC) is regarded as a greener separation technique than normal-phase liquid chromatography. In this work, we demonstrate the potential of SFC both for enantioseparation and achiral separation of a set of 11 chiral SCs obtained from internet vendors. On the basis of the results from HPLC measurement with optical rotation detector, two samples were present as racemates, whereas the others were not. Simultaneous baseline enantioseparation of both racemates in SFC confirmed its high enantioselective potential. Moreover, an SFC method with a specialized, diol-bonded stationary phase designed primarily for achiral screening purposes was presented.
A capillary electrophoresis-mass spectrometry (CE-MS) method was developed and validated for the determination of 19 amino acids and related compounds in excretions/secretions (ES) of Lucilia sericata larvae. Sample preparation consisted of dilution of ES with water, filtration and direct CE-MS analysis. Separation was performed with 50 mM formic acid as the background electrolyte, and methanol-water (1:1, v/v) containing 1% formic acid was used as sheath liquid. The total analysis time was 20 min. The method showed acceptable linearity, precision, accuracy, limit of detection (LOD), limit of quantification (LOQ), sensitivity, apparent recovery and short-term applicability for freshly prepared samples. Correlation coefficients for the calibration curves ranged from 0.983 to 0.998. Precision was within 18% at the lowest quality control level and within 15% at medium and high levels. Accuracy ranged from 83% to 118% at the lowest level and from 85% to 115% at the other levels. In larval ES, the most abundant compounds were threonine (565 ± 7 µM), tryptophan (455 ± 6 µM), anserine (404 ± 7 µM), histidine (330 ± 14 µM) and cystine (279 ± 4 µM). The method offers a simple workflow for targeted profiling of amino acids and related compounds in larval ES.
Acrylamide is a mutagenic and likely carcinogenic molecule. Incomplete polymerization of commercial acrylamide-based polymers leaves residual acrylamide molecules that pose a threat to human health and the environment. Acrylamide, being a polar molecule, is readily soluble in water but cannot be easily ionized in an aqueous environment. Therefore, the conventional capillary zone electrophoresis method is challenging to apply to acrylamide molecules. In this study, a capillary electrophoresis method that alters the acid-base properties of acrylamide under nonaqueous conditions, thereby imparting electrophoretic mobility to the molecule and increasing sensitivity through sample stacking, was used to detect acrylamide residues in absorbent polymers used in baby diapers. The method exhibited excellent analytical performance, with a linear range of 20-500 µg/L (R2 = 0.9999), limits of detection and quantification of 5.3 and 17.7 µg/L, respectively, and satisfactory precision and recovery values. The applicability of the proposed approach was demonstrated by analyzing five commercial baby diaper samples. Acrylamide was detected in all samples at concentrations ranging from 0.483 to 1.36 µg/g, indicating the presence of residual monomer associated with polyacrylamide-based superabsorbent polymers. These findings highlight the capability of combining nonaqueous capillary electrophoresis (NACE) with online preconcentration techniques for the sensitive determination of acrylamide in complex polymer-based matrices and emphasize the importance of monitoring such residues in hygiene products intended for infant use.
The environmental persistence of microplastic particles has raised increasing concerns for both human health and ecological systems. Owing to their intrinsic electrical properties and broad size distribution, electrokinetic-based microfluidic separation techniques have attracted increasing attention. In this study, a hybrid dielectrophoresis-bipolar electrode (DEP-BPE) microchannel is proposed to enhance particle separation across multiple size scales. A multiphysics numerical model coupled with particle tracking is developed to investigate the coupled electrokinetic mechanisms governing particle transport, including dielectrophoretic (DEP) force, electrophoretic migration, and electroosmotic flow (EOF)-induced hydrodynamic drag. The results show that increasing the applied voltage amplifies electrokinetic forces and significantly improves removal efficiency. However, the separation performance exhibits a non-monotonic dependence on voltage, arising from the competition between lateral DEP displacement and axial transport driven by electrophoresis and EOF. An optimal voltage condition is identified, under which trajectory differentiation is maximized without over deflection. Electrode spacing is found to primarily regulate the spatial distribution of electrokinetic interactions, exerting a limited influence on overall separation strength but significantly affecting the location of particle deflection and trajectory evolution. These findings demonstrate that particle separation in the DEP-BPE microchannel is governed by the coupling between force magnitude and spatial distribution and highlight the effectiveness of integrating DEP-induced stratification with BPE-driven trajectory divergence. This work provides mechanistic insights and design guidelines for high-efficiency microfluidic separation of polydisperse microplastic particles.
Vitamin D3 (VD3) and its metabolite 25-hydroxyvitamin D3 (25OHD3) are important biological molecules that play a significant role in human well-being. Conventional methods use highly hazardous solvents to extract them from their bound form, which is prior to their analysis in high-performance liquid chromatography (HPLC). Considering the World Health Organization's (WHO's) sustainable development goals (SDGs), there is a need for green solvents to extract valuable biological metabolites such as VD3 from human plasma. This study explored the potential of existing green solvents to liberate VD3 and 25OHD3 in human plasma samples. Five green solvents were shortlisted based on their physicochemical properties and low toxicity level. HPLC-UV chromatography conditions using a C8 column (BEH C8 1.7 µm, 2.1 × 150 mm2) were identified to achieve good peak-to-peak separation of 25OHD3 (2.74 min) and VD3 (4.5 min) within 5 min. The optimized method had an excellent limit of detection (LOD) for both VD3 (86 pg/mL) and 25OHD3 (89 pg/mL). Ethyl acetate has outperformed other green solvents and a solvent mixture of acetonitrile and methanol (in different ratios) in extracting both VD3 and 25(OH)D3 from human plasma samples (RSD < 2.2%). The stability of VD3 and 25OHD3 was tested with different plasma storage conditions (5°C, -20°C, -80°C, and lyophilized powder) for up to 60 days. Plasma stored at -20°C has significantly preserved the stability of VD3 and its metabolite 25OHD3, both of which were successfully extracted using ethyl acetate with minimal loss even on the 60th day of storage.
This study presents an affordable micellar electrokinetic chromatography (MEKC) method for the simultaneous analysis of six commonly used antiepileptic drugs: ethosuximide, phenobarbital, lamotrigine, phenytoin, carbamazepine, and diazepam. Systematic optimization of the method resulted in a running buffer containing 80 mM sodium dodecyl sulfate, 5% methanol, 2.5 mM phosphate, and 10 mM borate at pH 8.7, which provided robust and reliable separation. The method demonstrated excellent precision, with migration time %RSD values below 2% for both intraday and inter-day repeatability, and peak area %RSD values within acceptable limits (1.7%-3.7% intraday; 2.9%-6.3% inter-day). Linearity was confirmed for all analytes, with r2 values exceeding 0.99 and residuals randomly distributed around zero. Robustness testing showed that small variations in electrophoretic conditions did not significantly affect the resolution of the critical analyte pairs, which consistently remained above 1.5. Application of the method to five antiepileptic tablet formulations obtained from the Ethiopian market demonstrated its suitability as a rapid, reliable, and cost-effective screening tool. Overall, the developed MEKC method provides a practical analytical approach for antiepileptic medicines' quality assessment in resource-limited settings, supporting efforts to strengthen regulatory surveillance and safeguard public health.
The potential of multi-capillary electrophoresis (CE) for high-throughput analysis of legacy CE applications was investigated by optimisation of the separation of six pharmaceutical compounds on a single-capillary instrument, followed by transference of the method to an eight-capillary BioPhase 8800 system from SCIEX. Multi-CE had superior performance, allowing construction of calibration curves in a single run, and a five-fold reduction of run time per sample, improved linearity, accuracy and limits of detection. Method transfer from the single-capillary system required minor instrumental parameter adjustments using the same background electrolyte. The potential of multi-CE was shown via quantification of caffeine in a variety of energy drinks, demonstrating broad applicability where high-throughput and rapid analyses are desirable.
In this study, a capillary electrophoresis (CE) method was developed for the determination of naltrexone, an opioid antagonist, and its primary metabolite, 6-β-naltrexol (6-β-NTX). Naltrexone is commonly used in the treatment of opioid and alcohol dependence. Accurate quantification of such drugs and their metabolites is essential for ensuring therapeutic efficacy and safety. Reliable determination of NTX and 6-β-NTX in plasma is important for bioanalytical and clinical investigations involving naltrexone therapy. Method optimization was carried out using Box-Behnken design within the framework of response surface methodology to achieve maximum resolution between naltrexone and 6-β-naltrexol. Separation was performed at 15°C using a 10 mM phosphate buffer (pH 2.0) under an applied voltage of 20 kV, without the addition of organic modifiers. The method was validated in accordance with bioanalytical validation guidelines, providing a validated lower limit of quantification (LLOQ) of 0.05 µg/mL for both analytes, with precision (% relative standard deviation [RSD]) below 7% at the LLOQ. The validated method was successfully applied to plasma samples obtained from patients receiving treatment for alcohol and opioid use disorders. Furthermore, the environmental sustainability of the proposed CE method and its sample preparation steps was assessed using green analytical chemistry metrics, such as AGREE, AGREEprep, and MoGAPI, demonstrating its greener profile compared to reported methods.
Accurate particle characterization is critical for biomedical research, yet electrical impedance flow cytometry suffers from measurement inaccuracies due to the positional heterogeneity of particles within microfluidic channels. In large-scale microchannels, off-axis particle trajectories lead to significant waveform distortion and the attenuation of key characteristic features, undermining measurement precision. To address this issue, this study presents a novel signal-processing framework centered on a full-waveform calibration factor (CF). The CF is theoretically grounded in the exponential decay of the electric field along the vertical axis of coplanar electrodes and is derived from comprehensive waveform features rather than localized extrema, ensuring robustness against the distortions prevalent in high-flow conditions. Coupled with a dedicated real-time algorithm, it corrects for vertical position-induced errors in particle sizing. The effectiveness of this method was validated through a combination of finite element simulation and experimental impedance measurement. The system's performance is demonstrated by accurately discriminating polystyrene microsphere populations (10 μ m , 15 μ m , and their mixture) and by resolving the size distributions of viable versus non-viable HEK-293T cells. Statistical analysis ( N ≥ 500 events per group, p < 0.001 ) confirms significant improvement in size-distribution accuracy after calibration. Furthermore, this study designs an inverted microfluidic chip enabling real-time, optical sensing of particle stream height within the impedance detection zone and supporting position-independent impedance cytometry applicable to continuous-flow particle streams. Experimental calibration achieves a strong linear correlation ( R 2 = 0.970 ) between the sensor response and measured height, confirming the method's utility for spatially resolved impedance cytometry.
Globally, cancer morbidity and death are rising quickly, making it imperative to develop a workable plan for early cancer patient identification and treatment outcome prediction. Liquid biopsy, a minimally invasive and repeatable technique, can replace the restrictions of tissue biopsy by detecting, assessing, and tracking cancer in any bodily fluid, including human blood. This novel diagnostic technique offers crucial data for tracking and recognizing tumor genomes in samples of physiological fluids. Through minimally invasive methods, the identification of tumor-origin biological components, such as circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), circulating microRNAs (miRNAs), exosomes, and autoantibodies in serum, plasma, saliva, and urine, allows for disease monitoring, early diagnosis, and assessment of treatment response. The goal of this study is to provide a comprehensive summary of the most recent discoveries and applications of liquid biopsy technology for detecting cancer biomarkers, with an emphasis on the years 2005-2025. When used in conjunction with other test results, liquid biopsy is also advantageous for early recurrence detection, monitoring patients who are considered to be at high risk of getting cancer and improving diagnosis. Combining patient history, clinical results, and biopsy biomarker amounts will enable more precise and timely diagnosis thanks to developments in analytical methods and informatics. This review thoroughly examined the biosynthesis, significance, and potential role of four well-known biological markers in tumor diagnosis and treatment. In addition, the advances and challenges in detection technologies for these analytes, as well as potential solutions to address these issues, were also discussed. Finally, we discuss the advantages and disadvantages of liquid biopsy, along with suggestions for its future advancement.
This study evaluated kinship identification using 19 short tandem repeats (STRs) from AGCU EX22 kit, 119 microhaplotypes (52 in Panel A + 67 in Panel B), and a theoretical 9622 genome-wide single nucleotide polymorphisms (SNPs) panel (The 9K). The system power was assessed accounting for linkage on the basis of 198 Chinese Southern Han (CHS) family samples and simulated data. STR + Panels A and B distinguished full-sibling (FS) from unrelated (un), with second-degree effectiveness above 0.96 when log10(LR) threshold was 4 and low false positive rate (<0.06%), but were insufficient for more distant kinship identification alone. The 9K panel was sufficient to separate third-degree from un but not for fourth-degree or more distant relatives. For discrimination among different kinships, STR + Panels A and B successfully distinguished all FS from half-siblings (HS), uncle/aunt-nephew/niece (UN), and grandparents-grandson/granddaughter (GS) in real data, with minimal overlaps (<0.2%). Discriminating second- and third-degree or within second-degree relatives seems very challenging, even for 9K panel. Including a carefully selected additional relative (AR) may improve discrimination between GS and UN/HS, such as AR (GS-un, which is GS for one person and un for the other) and AR (parent/child (PC)-UN). Similarly, an AR (PC-GS) may help distinguish UN from GS/HS, but there was slightly improved efficiency for HS.
Electrokinetic extraction (EKE), coupled with polymer inclusion membranes (PIMs) for colourimetric detection, offers a promising approach for extracting metal ions from solid matrices, such as sand, without sample pretreatment. Our EKE system consists of a formic acid gel positioned at the cathode side to neutralise hydroxide ions generated by electrolysis during the EKE of Cu(II), whereas the anode side contains the sample compartment, prepared from a syringe tube into which the sample is placed. The PIM is sandwiched between these compartments to accumulate Cu(II) via EKE through the sand and into the PIM within which it complexes with a colour-forming reagent, 1-(2-pyridylazo)-2-naphthol (PAN), enabling quantification via colourimetric analysis. The system has been optimised to expand the quantification range of Cu(II), thus allowing greater applicability to a wider range of samples with different levels of heavy metals. Increasing the column diameter extended the upper limit of the quantification range from 7.5 mg kg-1 (4.5 mm column diameter) to 30.0 mg kg-1 (13.5 mm column diameter). Concurrently, optimisation of the PIM composition, containing 43.3 wt% cellulose triacetate (CTA)-56.0 wt% di-(2-ethylhexyl) phosphoric acid (D2EHPA)-0.8 wt% PAN, enhanced the overall recovery of Cu(II) from 64% ± 7% to 90% ± 4%. Overall, the optimised system has achieved a quantification range of 2.8-30.0 mg kg-1 of Cu(II), with an LOD of 0.9 and LOQ of 2.8 mg kg-1 of Cu(II).
Neuraminidase inhibitors (NAIs) are a crucial therapy for combatting the influenza virus. This study employed an at-line nanofractionation technique to precisely localized potential NAIs in the extract of Humulus lupulus L. Twelve potential compounds, mainly phloroglucinol derivatives, were screened and identified. Seven of these compounds were subsequently isolated, purified, and structurally elucidated by NMR. Among them, Compound 5 showed remarkable inhibitory activity against both neuraminidase (NA, IC50 = 0.8 µM) and the H3N2 influenza virus (EC50 = 3.8 µM), confirming its potential as a lead compound for anti-influenza development. Compounds 4 and 8, identified as hitherto uncharacterized phloroglucinol derivatives, also demonstrated significant inhibition against NA and the H3N2 influenza virus. Molecular docking revealed that Compounds 4 and 5 exhibited superior binding affinities compared to oseltamivir, with 4 forming critical hydrogen bonds with acidic residues (Glu119, Glu227, and Asp151) in the "150-cavity," which significantly enhances its inhibitory potency against NAs.
Liquid chromatographic (LC) and capillary electrokinetic chromatography (EKC) methods with ultraviolet/diode array detection were developed for the enantioseparation of five azoles: econazole (ECO), miconazole (MICO), imazalil (IMA), ketoconazole (KET), and penconazole (PEN). The chiral selectors investigated were human serum albumin (HSA) and eight cyclodextrins (CDs), exploited in LC and EKC, respectively. HSA LC offered partial enantioseparation of IMA and, less effectively, of PEN. Interestingly, these azoles share a high degree of molecular similarity, as confirmed by in silico calculations. This may suggest that a single enantiomer achieves preferential access to enantioselective sites of the protein. To address the limited enantioselectivity of HSA for these azoles, CDs were explored as chiral selectors where EKC was preferable to LC due to its superior separation efficiency. The chiral discrimination capabilities of eight CDs were evaluated for these azole derivatives, aiming for fast separations with minimal amounts of CDs. Effective enantioseparation was achieved for ECO, MICO, IMA, and KET, using two of the tested CDs: 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TM-β-CD). Satisfactory resolutions were obtained using a 40 mM phosphate buffer (pH 3.2) with 1 mM HP-β-CD for ECO and MICO and 8 mM TM-β-CD for KET. For IMA, the optimal conditions consisted of a 20 mM phosphate buffer with 3 mM HP-β-CD. None of the tested CDs were effective for the enantiomeric separation of PEN; therefore, a dual CD system was developed for the first time for this compound, employing succinyl-β-CD (Succ-β-CD) in combination with HP-β-CD in a borax buffer under basic conditions (pH 9.4), enabling complete enantioseparation of PEN. The low concentration of CDs required under optimal conditions renders the developed methods highly cost-effective.
Electrokinetics, including dielectrophoresis, electroosmosis and other phenomena, have become a popular technique for manipulating particles on the microscale using electric fields. Concurrently, CMOS microchips have become the dominant global technology. The combination of electrokinetics with CMOS appears ideal, as both utilise electric potentials, with the ability to make highly functional and scalable actuating systems. Since the first demonstration of electrokinetics implemented as part of a CMOS system in 2003, 49 further studies were published. But whilst the first study led to a commercialised product, those that followed have not achieved the same success. This review surveys the available literature on CMOS-based electrokinetic systems and highlight key trends in design. The obstacles blocking the field from greater success are explored and opportunities are identified, with future perspectives provided throughout. The review shows that, currently, the foremost limitation for CMOS-based electrokinetic systems lies with the front-end-namely, the electrode systems being employed. The need to extend beyond the planar configurations currently being used and fabricate 3D electrodes on-CMOS that can operate within high conductivity environments is put forward. This discussion then leads into a review on fabrication approaches for 3D electrodes with a specific focus on those compatible with a CMOS system.
Droplet electrophoresis is one of the most commonly used methods for measuring the charge at two-liquid interfaces. However, there is still a lack of analytical solutions that consider the ion concentration polarization mechanism with asymmetric ion distribution under high surface charge. Based on the thin electric double layer assumption, we construct the asymptotic form of the macroscopic model of dielectric droplet electrophoresis and establish the coarse-grained effective interface condition across the diffuse layer regions through the heuristic treatment extending the method of matched asymptotic expansion, revealing the coupling mechanism between ion concentration polarization and permittivity-induced inhomogeneous charging. An analytical solution under the weak-external-field limit is provided, demonstrating a nonmonotonic dependence of electrophoretic mobility on the ζ potential under weak external electric fields. By integrating previous experimental results on droplet electrophoresis, a concise and physically meaningful quantitative model of the charging mechanism for general nonpolar oil is established.
Green Chemistry 2026 issue, focusing on drug impurity analysis (2 reviews), biosourced preservatives (by LC and SFC), phosphate syrup (by IC), insulin and dapagliflozin (by CE).
