Cost-effective capillary electrophoresis with contactless conductivity detection for quality control of beta-lactam antibiotics

Validated chromatographic approach for determination of two ternary mixtures in newly approved formulations for helicobacter pylori eradication: assessment of greenness profile and content uniformity

A new, sensitive, and rapid isocratic reversed phase chromatographic method (RP-HPLC-UV) was developed for simultaneous separation of two newly co-formulated antiulcer mixtures; Amoxicillin, Vonoprazan and Clarithromycin [Mixture (I)], and Amoxicillin, Lansoprazole and Clarithromycin [Mixture (II)]. Analytical separation was performed using a Promosil C18 column and ultraviolet detection at 210 nm. The separation was achieved within only 8 min. For both mixtures, an aqueous solution, composed of (Acetonitrile: Methanol: 0. 2 M phosphoric acid) within ratio of (30: 30: 40) adjusted to final pH 3.0, was the mobile phase. This method was validated as per the International Conference on Harmonization guidelines. The linearity ranges of these proposed method of the (Mixture (I)) were 25.0-400.0 µg/mL Amoxicillin, 0.5-8.0 µg/mL Vonoprazan, and 12.5-200.0 µg/mL Clarithromycin. And the linearity ranges of the (Mixture (II)) were 10.0-300.0 µg/mL Amoxicillin, 0.3-9.0 µg/mL Lansoprazole and 5.0-150.0 µg/mL Clarithromycin. This method was firstly applied for effective separation of Amoxicillin, Vonoprazan and Clarithromycin [Mixture (I)]. It fulfilled good repeatability, sensitivity, and accuracy (R.S.D. < 2.0%). The mean recoveries of the analytes in their Tri-Pak formulations were acceptable. The greenness of the developed chromatographic methods was assessed using an Eco-scale method and it was applied for content uniformity testing as per the United States Pharmacopoeia (USP) and the acceptance value of Amoxicillin, in Mixture (I) was 2.88, the acceptance values for Amoxicillin, Lansoprazole in Mixture (II) were 2.592, 2.424, respectively.

Exploring the Thermal-Oxidative Stability of Azithromycin Using a Thermoactivated Sensor Based on Cerium Molybdate and Multi-Walled Carbon Nanotubes

The chemical stability of azithromycin (AZM) may be compromised depending on the imposed thermo-oxidative conditions. This report addresses evidence of this process under varying conditions of temperature (20-80 °C), exposure time to UV radiation (1-3 h irradiation at 257 nm), and air saturation (1-3 h saturation with atmospheric air at 1.2 L min-1 and 15 kPa) through electrochemical measurements performed with a thermoactivated cerium molybdate (Ce2(MoO4)3)/multi-walled carbon nanotubes (MWCNT)-based composite electrode. Thermal treatment at 120 °C led to coordinated water elimination in Ce2(MoO4)3, improving its electrocatalytic effect on antibiotic oxidation, while MWCNT were essential to reduce the charge-transfer resistance and promote signal amplification. Theoretical-experimental data revealed remarkable reactivity for the irreversible oxidation of AZM on the working sensor using phosphate buffer (pH = 8) prepared in CH3OH/H2O (10:90%, v/v). Highly sensitive (230 nM detection limit) and precise (RSD < 4.0%) measurements were recorded under these conditions. The results also showed that AZM reduces its half-life as the temperature, exposure time to UV radiation, and air saturation increase. This fact reinforces the need for continuous quality control of AZM-based pharmaceuticals, using conditions closer to those observed during their transport and storage, reducing impacts on consumers' health.

Solid phase extraction technology combined with UPLC-MS/MS: a method for detecting 20 β-lactamase antibiotics traces in goat's milk

We develop and validate a method for the rapid determination and identification of 20 β-lactamase antibiotics traces in goat's milk by combining the solid phase extraction technology with ultra-high performance liquid chromatography-tandem mass spectrometry. Goat milk samples were extracted with acetonitrile twice. The supernatant was then extracted and cleaned by solid-phase extraction using divinylbenzene and N-vinylpyrrolidone copolymer. The method was validated, with limits of quantification (LOQs) of 0.3 μg kg-1, specificities of 1/3 LOQ, linearities (R2) > 0.99, recoveries of 80-110%, repeatabilities <10.0%, and intermediate precisions <10.0%. The developed method was suitable for the routine analysis of β-lactamase antibiotics residues in goat's milk and was used to test 76 goat milk samples produced in China.

Design and fabrication of a competitive lateral flow assay using gold nanoparticle as capture probe for the rapid and on-site detection of penicillin antibiotic in food samples

Lateral flow assays (LFAs) are among the utmost cost-efficient, paper-based point-of-care (POC) diagnostic devices. Herein, we have reported the fabrication of a competitive LFA for on-site detection of penicillin. Various parameters such as Ab concentration for conjugation, Pen-BSA conjugate concentration, pore size of membrane, and blocking buffer were standardised for the fabrication of LFA. Different concentrations of penicillin (1 pM-1 mM) were added to the sample pad to observe the color intensity. The visual detection limit (LOD) achieved from the LFA was 10 nM for Penicillin that correlated with the LOD calculated from the 'ColorGrab' colorimeter application. Additionally, LFA showed insignificant cross reactivity with other β-lactam antibiotics and were also validated with spiked food samples such as milk, meat and egg. Hence, the fabricated LFA can be successfully utilised for the POC detection of penicillin in food samples on large scale.

Development and Validation of a Capillary Zone Electrophoresis-Tandem Mass Spectrometry Method for Simultaneous Quantification of Eight β-Lactam Antibiotics and Two β-Lactamase Inhibitors in Plasma Samples

Monitoring plasma concentrations of β-lactam antibiotics is crucial, particularly in critically ill patients, where variations in concentrations can lead to treatment failure or adverse events. Standardized antimicrobial regimens may not be effective for all patients, especially in special groups with altered physiological parameters. Pharmacokinetic/pharmacodynamic (PK/PD) studies highlight the time-dependent antibacterial activity of these antibiotics, emphasizing the need for personalized dosing. Therapeutic drug monitoring (TDM) is essential, requiring rapid and accurate analytical methods for precise determination of drugs in biological material (typically plasma or serum). This study presents a novel capillary zone electrophoresis-tandem mass spectrometry (CZE-MS/MS) method designed for the simultaneous quantification of five penicillin antibiotics, two cephalosporins, one carbapenem, and two β-lactamase inhibitors in a single run. The method involves a simple sample pretreatment-precipitation with organic solvent-and has a run time of 20 min. Optimization of CZE separation conditions revealed that 20 mM ammonium hydrogen carbonate (NH4HCO3) serves as the optimal background electrolyte (BGE). Positive electrospray ionization (ESI) mode, with isopropyl alcohol (IP)/10 mM ammonium formate water solution (50/50, v/v) as the sheath liquid, was identified as the optimal condition for MS detection. Method validation according to the Food and Drug Administration (FDA) guideline for development of bioanalytical methods demonstrated satisfactory selectivity, linearity, recovery, robustness, and stability. The method's practicality was evaluated using the Blue Applicability Grade Index (BAGI), yielding a score of 77.5. Moreover, the greenness of the proposed method was evaluated by two commonly used metric tools-Analytical GREEnness (AGREE) and Green Analytical Procedure Index (GAPI). The developed CZE-MS/MS method offers a practical and reliable approach for quantifying a broad spectrum of β-lactam antibiotics in plasma. Its ability to simultaneously quantify multiple analytes in a single run, coupled with a straightforward sample pretreatment, positions it as a valuable and prospective tool for TDM in critically ill patients.

Strategies for capillary electrophoresis: Method development and validation for pharmaceutical and biological applications-Updated and completely revised edition

This review is in support of the development of selective, precise, fast, and validated capillary electrophoresis (CE) methods. It follows up a similar article from 1998, Wätzig H, Degenhardt M, Kunkel A. "Strategies for capillary electrophoresis: method development and validation for pharmaceutical and biological applications," pointing out which fundamentals are still valid and at the same time showing the enormous achievements in the last 25 years. The structures of both reviews are widely similar, in order to facilitate their simultaneous use. Focusing on pharmaceutical and biological applications, the successful use of CE is now demonstrated by more than 600 carefully selected references. Many of those are recent reviews; therefore, a significant overview about the field is provided. There are extra sections about sample pretreatment related to CE and microchip CE, and a completely revised section about method development for protein analytes and biomolecules in general. The general strategies for method development are summed up with regard to selectivity, efficiency, precision, analysis time, limit of detection, sample pretreatment requirements, and validation.

A five-electrode capacitively coupled contactless conductivity detector with a low limit of detection

The conductivity detector is a broadly used device that allows for the highly efficient detection of analytes, and continuous efforts have been directed toward lowering the limit of detection. In this study, a five-electrode capacitively coupled contactless conductivity detector (TIC⁴D) is proposed, which uses copper mesh between the electrodes for a grounding shield to reduce the interference of stray capacitance and noise. After adding the copper mesh shield, the difference value between the response signal and baseline at low KCl concentration is effectively increased, achieving 33 mV for 10^-9 M KCl solution. Meanwhile, for the unshielded detector, the difference is only 18 mV for the KCl solution at the same concentration. The response signal shows a linear function of the logarithm at the range of 10^-4 M to 10^-5 M KCl solution, and the TIC⁴D detector displays a higher slope (0.8448) than the conventional single-input capacitively coupled contactless conductivity detector (C⁴D: 0.5579) and dual-input capacitively coupled contactless conductivity detectors (DIC⁴D: 0.6173). Moreover, two TIC⁴D detectors are combined to achieve a dual-channel six-input differential capacitively coupled contactless conductivity detector (SIDC⁴D), reducing the high baseline levels caused by the multi-signal input. By differentially amplifying the output signal, the high baseline levels and noise interference can be effectively reduced. For the 10^-3 M KCl solution, the ratio of the response signal to baseline for SIDC⁴D can reach 8.500, almost 7 times that of TIC⁴D, and a lower limit of detection (LOD) of 3 × 10^-10 M is also achieved. This work may open a new door based on coupled contactless conductivity for detection performance.

Green Analytical Method for Simultaneous Determination of Glucosamine and Calcium in Dietary Supplements by Capillary Electrophoresis with Capacitively Coupled Contactless Conductivity Detection

The need for analytical methods that are fast, affordable, and ecologically friendly is expanding. Because of its low solvent consumption, minimal waste production, and speedy analysis, capillary electrophoresis is considered a "green" choice among analytical separation methods. With these "green" features, we have utilized the capillary electrophoresis method with capacitively coupled contactless conductivity detection (CE-C⁴D) to simultaneously determine glucosamine and Ca²⁺ in dietary supplements. The CE analysis was performed in fused silica capillaries (50 μm inner diameter, 40 cm total length, 30 cm effective length), and the analytical time was around 5 min. After optimization, the CE conditions for selective determination of glucosamine and Ca²⁺ were obtained, including a 10 mM tris (hydroxymethyl) aminomethane/acetic acid (Tris/Ace) buffer of pH 5.0 as the background electrolyte; separation voltage of 20 kV; and hydrodynamic injection (siphoning) at 25 cm height for 30 s. The method illustrated good linearity over the concentration range of 5.00 to 200 mg/L of for glucosamine (R ² = 0.9994) and 1.00 to 100 mg/L for Ca²⁺ (R ² = 0.9994). Under the optimum conditions, the detection limit of glucosamine was 1.00 mg/L, while that of Ca²⁺ was 0.05 mg/L. The validated method successfully analyzed glucosamine and Ca²⁺ in seven dietary supplement samples. The measured concentrations were generally in line with the values of label claims and with cross-checking data from reference methods (HPLC and ICP-OES).

Ultrasensitive immunosensing of Penicillin G in food samples using reduced graphene oxide (rGO) decorated electrode surface

The impact of uncontrolled antibiotic use in animals has subsequently led to emergence of antibiotic-resistant bacteria among humans due to consumption of animal by-products. Hence, to investigate antibiotic contamination in animal origin food products, we have developed a reduced graphene oxide (rGO) based immunosensor using fabricated electrode conjugated with anti-Penicillin antibody (rGO/Pen-Ab) for sensitive detection of Penicillin G. To execute this, Penicillin was first conjugated with Bovine Serum Albumin (BSA) which was confirmed via chromatographic, spectroscopic and electrophoretic-based techniques against both the in-house developed Penicillin conjugate (Pen-BSA) as well as the commercial Penicillin conjugate (Com-Pen-BSA). Further, we fabricated electrode based on one step synthesized rGO and immobilized with antibodies generated against Pen-BSA (Pen-Ab), and Com-Pen-BSA (Com-Pen-Ab), separately for detection of Penicillin. Each synthesis and conjugation step was confirmed by different spectroscopic methods. For efficient working of the electrode, various parameters were optimized using Voltammetry. The limit of detection for Penicillin G against Pen-Ab and Com-Pen-Ab was determined as 0.724 pM and 0.668 pM respectively and both displayed negligible cross reactivity against other β-lactam antibiotics (Cefalexin and Ampicillin). Furthermore, antibiotics were also detected in spiked milk, egg and meat samples and the electrode was evaluated for repeatability and storage stability. In conclusion, in-house developed Pen-Ab showed better sensitivity as compared to Com-Pen-Ab. The fabricated rGO/Pen-Ab biosensor shows future potential for rapid detection of penicillin and other β-lactam antibiotics for safe consumption of animal by-products in humans.

Simultaneous determination of vitamin B6 and magnesium using capillary electrophoresis coupled with contactless conductivity detection: Method development, validation, and application to pharmaceutical and nutraceutical samples

Vitamins and minerals are usually incorporated in pharmaceutical and nutraceutical products, but a simple, rapid, and inexpensive analytical method for their simultaneous determination is still lacking. In this study, we developed a quantification method for pyridoxine (vitamin B₆) and magnesium (Mg) by using purpose-made capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C⁴D) instrument. Main analytical conditions include: fused silica capillary (total length 55 cm, effective length 40 cm, inner diameter 50 μm); background electrolyte consisted of 10 mM L-arginine/acetic acid (pH 5) with 20% acetonitrile; separation voltage + 20 kV; hydrodynamic injection (siphoning at 20 cm in 25 s). Detection limits of vitamin B₆ and Mg were 1 and 0.1 mg/L, respectively. Good linearity (R² > 0.999) was observed for vitamin B₆ and Mg calibration curves over concentration ranges of 3-100 and 0.3-200 mg/L, respectively. The method was applied to analyze vitamin B₆ and Mg in several pharmaceutical and nutraceutical samples. The analytical results obtained by our method were in good agreement with reference methods (i.e., HPLC for vitamin B₆ and ICP-OES for Mg). High-efficient and low-cost CE-C⁴D method can accordingly serve as a promising tool for concurrent analysis of inorganic and organic species in pharmaceutical and nutraceutical analysis.

A new NiS nanoparticles-enhanced chemiluminescence method for determination of cephalexin in the pharmaceuticals and spiked human serum

It is reported that NiS nanoparticles (NPs) can enhance the light emission from chemiluminescence (CL) reaction of luminol-O₂ (λ_max = 425 nm), remarkably. Additionally, it was shown that cephalexin (CEF) could further increase the intensity of light emitted from NiS NPs-luminol-O₂ CL reaction. Inspired in these findings, we intended to develop a new and straightforward CL method for the determination of CEF. A calibration graph over the range of 1.00 × 10^-6 - 4.00 × 10^-5 mol L^-1 was established. The limit of detection (LOD) of the CL method was 8.00 × 10^-7 mol L^-1 . The coefficient of variation (CV) of the CL methods was 2.20% (n = 6) for the measurement of 6.00 × 10^-6 mol L^-1 CEF. NiS NPs were produced by exploiting the precipitation method and identified by employing several spectroscopic approaches. The proposed CL method was successfully used to measure CEF in some pharmaceutical and spiked human serum. The chemical mechanism governing the CL reaction was briefly explained.

Monitoring of amoxicilline and ceftazidime in the microdialysate of diabetic foot and serum by capillary electrophoresis with contactless conductivity detection

Determination of the broad-spectrum antibiotics amoxicilline (AMX) and ceftazidime (CTZ) in blood serum and microdialysates of the subcutaneous tissue of the lower limbs is performed using CE with contactless conductivity detection (C⁴ D). Baseline separation of AMX is achieved in 0.5 M acetic acid as the background electrolyte and separation of CTZ in 3.2 M acetic acid with addition of 13% v/v methanol. The CE-C⁴ D determination is performed in a 25 µm capillary with suppression of the EOF using INST-coating on an effective length of 18 cm and the attained migration time is 4.2 min for AMX and 4.4 min for CTZ. The analysis was performed using 20 µl of serum and 15 µl of microdialysate, treated by the addition of acetonitrile in a ratio of 1/3 v/v and the sample is injected into the capillary using the large volume sample stacking technique. The LOQ attained in the microdialysate is 148 ng/ml for AMX and 339 ng/ml for CTZ, and in serum 143 ng/ml for AMX and 318 ng/ml for CTZ. The CE-C⁴ D method is employed for monitoring the passage of AMX and CTZ from the blood circulatory system into the subcutaneous tissue at the sites of diabetic ulceration in patients suffering from diabetic foot syndrome and also for measuring the pharmacokinetics following intravenous application of bolus antibiotic doses.

Applications of capillary electrophoresis in the fields of environmental, pharmaceutical, clinical and food analysis (2019-2021)

So far, the potential of capillary electrophoresis (CE) in the application fields has been increasingly excavated due to the advantages of simple operation, short analysis time, high-resolution, less sample consumption and low cost. This review examines the implementations and advancements of CE in different application fields (environmental, pharmaceutical, clinical and food analysis) covering the literature from 2019 to 2021. In addition, ultrasmall sample injection volume (nanoliter range) and short optical path lead to relatively low concentration sensitivity of the most frequently used UV-absorption spectrophotometric detection, so the pretreatment technology being developed has been gradually utilized to overcome this problem. Despite the review is focused on the development of CE in the fields of environmental, pharmaceutical, clinical and food analysis, the new sample pretreatment techniques of microextraction and enrichment which fit excellently to CE in recent three years are also described briefly. This article is protected by copyright. All rights reserved.

A ratiometric fluorescent probe based on carbon dots and gold nanocluster encapsulated metal-organic framework for detection of cephalexin residues in milk

Herein, we report a ratiometric fluorescent probe based on in situ incorporation of both Gold nanoclusters (AuNCs) and Green emitting carbon dots (gCDs) into zeolitic imidazolate framework-8 (ZIF-8) to analysis of Cephalexin (CFX). Under a single excitation wavelength of 400 nm, the sensor exhibits dual-emissions centered at 520 and 630 nm. The fluorescence of AuNCs (630 nm) is selectively quenched by CFX, whereas the fluorescence of gCDs (520 nm) remainsalmostconstant. The ratiometric fluorescence signal (F₅₂₀/F₆₃₀) of the prepared composite (gCDc/AuNCs @ ZIF-8) is linearly proportional to the concentration of CFX from 0.1 to 6 ng/mL with a low detection limit (LOD) of 0.04 ng/mL, which is below the maximum residues limit (MRL) of 100 ng/mL set by the Food and Drug Administration (FDA). Moreover, the designed sensing platform was successfully applied to detect CFX in the milk samples.

A smartphone-combined ratiometric fluorescence probe for specifically and visibly detecting cephalexin

A smartphone-combined dual-emission ratiometric fluorescence probe for specifically and visibly detecting cephalexin was first designed. In the probe, blue-emitting fluorescent carbon dots (CDs) was synthesized and covered with a layer of silica spacer. Red-emitting fluorescent CdTe QDs (r-QDs) was grafted onto the silica nanospheres as an analytical probe. Then, the cephalexin antibody was covalent grafted to the ratio sensor to increase the selectivity. The ratio of fluorescence intensity (FL) of r-QDs and CDs was quenched with the increasing concentration of cephalexin. The detection method has good linear response in the range of 1-500 μM and the detection limit was 0.7 μM. Then portable device based on smartphone detection was constructed according to the color change under UV lamp. The detection image was obtained through the smartphone camera, and the color picker APP installed in the smartphone captured the RGB value of the image. In addition, this method was also used to determine the amount of cephalexin in milk samples with recovery of 94.1%-102.2%. These results showed that it was a portable, simple and visible method to detect cephalexin in food analysis and environmental monitoring.

Low-cost and open-source strategies for chemical separations

In recent years, a trend toward utilizing open access resources for laboratory research has begun. Open-source design strategies for scientific hardware rely upon the use of widely available parts, especially those that can be directly printed using additive manufacturing techniques and electronic components that can be connected to low-cost microcontrollers. Open-source software eliminates the need for expensive commercial licenses and provides the opportunity to design programs for specific needs. In this review, the impact of the "open-source movement" within the field of chemical separations is described, primarily through a comprehensive look at research in this area over the past five years. Topics that are covered include general laboratory equipment, sample preparation techniques, separations-based analysis, detection strategies, electronic system control, and software for data processing. Remaining hurdles and possible opportunities for further adoption of open-source approaches in the context of these separations-related topics are also discussed.

Ratiometric Dual Signal-Enhancing-Based Electrochemical Biosensor for Ultrasensitive Kanamycin Detection

Based on the signal amplification elements of planar VS₂/AuNPs nanocomposites and CoFe₂O₄ nanozyme, we herein developed an electrochemical biosensor for sensitive kanamycin (Kana) quantification. A ratiometric sensing platform was presented by incorporating VS₂/AuNPs nanocomposites as a support material with excellent conductivity and high specific surface area, as well as hairpin DNA (hDNA) with complementary hybridization of biotinylated Kana-aptamer. In addition, streptavidin-functionalized CoFe₂O₄ nanozyme with superior peroxidase-like catalytic activity were immobilized onto the aptasensor, hence the peroxidase-like catalytic reaction could yield amplified electrochemical signals. With the presence of Kana, the aptamer-biorecognition resulted in a quantitative decrease of nanozyme accumulation and an increase of methylene blue response. Under optimal conditions, the electrochemical signal ratio of the aptasensor revealed a linear relation along with the logarithmic concentration of Kana from 1 pM to 1 μM, with the limit of detection reaching to 0.5 pM. Moreover, this aptasensor exhibited excellent precision, as well as high repeatability, hence possessing potentials in real samples and for diverse targets detection by easy replacement of the matched aptamer.

Capacitively coupled contactless conductivity detection for analytical techniques - Developments from 2018 to 2020

The developments of analytical contactless conductivity measurements based on capacitive coupling over the two years from mid-2018 to mid-2020 are covered. This mostly concerns applications of the technique in zone electrophoresis employing conventional capillaries and to a lesser extent lab-on-chip devices. However, its use for the detection in several other flow-based analytical methods has also been reported. Detection of bubbles and measurements of flow rates in two-phase flows are also recurring themes. A few new applications in stagnant aqueous samples, e.g. endpoint detection in titrations and measurement on paper-based devices, have been reported. Some variations of the design of the measuring cells and their read-out electronics have also been described.

Capillary electrophoretic methods for quality control analyses of pharmaceuticals: A review

Capillary electrophoresis represents a promising technique in the field of pharmaceutical analysis. The presented review provides a summary of capillary electrophoretic methods suitable for routine quality control analyses of small molecule drugs published since 2015. In total, more than 80 discussed methods are sorted into three main sections according to the applied electroseparation modes (capillary zone electrophoresis, electrokinetic chromatography, and micellar, microemulsion, and liposome-electrokinetic chromatography) and further subsections according to the applied detection techniques (UV, capacitively coupled contactless conductivity detection, and mass spectrometry). Key parameters of the procedures are summarized in four concise tables. The presented applications cover analyses of active pharmaceutical ingredients and their related substances such as degradation products or enantiomeric impurities. The contribution of reported results to the current knowledge of separation science and general aspects of the practical applications of capillary electrophoretic methods are also discussed.

Low-cost and versatile analytical tool with purpose-made capillary electrophoresis coupled to contactless conductivity detection: Application to antibiotics quality control in Vietnam

In this study, the development of our purpose-made capacitively coupled contactless conductivity detection (C⁴ D) for CE is reported. These systems have been employed as a simple, versatile, and cost-effective analytical tool. CE-C⁴ D devices, whose principle is based on the control of the ion movements under an electrical field, can be constructed even with a modest financial budget and limited infrastructure. A featured application was developed for quality control of antimicrobial drugs using CE-C⁴ D, with most recent work on determination of aminoglycoside and glycopeptide antibiotics being communicated. For aminoglycosides, the development of CE-C⁴ D methods was adapted to two categories. The first one includes drugs (liquid or powder form) for intravenous injection, containing either amikacin, streptomycin, kanamycin A, or kanamycin B. The second one covers drugs for eye drops (liquid or ointment form), containing either neomycin, tobramycin, or polymyxin. The CE-C⁴ D method development was also made for determination of some popular glycopeptide antibiotics in Vietnam, including vancomycin and teicoplanin. The best detection limit achieved using the developed CE-C⁴ D methods was 0.5 mg/L. Good agreement between results from CE-C⁴ D and the confirmation method (HPLC- Photometric Diode Array ) was achieved, with their result deviations less than 8% and 13% for aminoglycoside and glycopeptide antibiotics, respectively.

Modular instrumentation for capillary electrophoresis with laser induced fluorescence detection using plug-and-play microfluidic, electrophoretic and optic modules

This study reports on the development of a novel instrument for capillary electrophoresis (CE) coupled with laser induced fluorescence (LIF) detection that is inspired by the Lego-toy concept. The Lego CE-LIF design is an evolution of purpose-made CE instrumentation, allowing the users to construct their own analytical device with a high degree of standardization (i.e. a "standard" setup) without requirement of mechanical and electronic workshop facilities. To allow instrument reproduction outside the original fabrication laboratory, which is not trivial for in-house-built CE systems, the new design is based on unprecedent 'plugging' hyphenation of various off-the-shelf parts available for microfluidics, optics and electrophoresis. To render the operation with Lego CE-LIF optimal, we developed a new background electrolyte (BGE), using for the first time extremely high concentrations of zwitterionic and large weakly charged species for much improvement of detection sensitivity. The Lego CE-LIF was demonstrated for separation and detection of oligosaccharides labelled with 8-aminopyrene-1,3,6-trisulfonic acid (APTS). The new gel-free BGE for oligosaccharide analysis also allowed simplification of the conventional CE-LIF protocol used with commercial instruments while keeping satisfactory separation performances. Furthermore, the new BGE is fully compatible with a non-thermostatted Lego CE instrument thanks to low current and therefore low heat generation under application of a high voltage.

Application of Capillary Electrophoresis with Capacitively Coupled Contactless Conductivity Detection (CE-C4D): 2017-2020

Capacitively coupled contactless conductivity detection (C⁴D) has emerged as influential to detect analytes that do not have chromogenic or fluorogenic functional group. Since our last review several new capillary electrophoresis (CE) methods coupled with (CE-C⁴D) have been communicated. The aim of this review is to give an update of the almost all the new applications of CE-C⁴D in the field of pharmaceutical, food and biomedical analysis covering the period from 2017 to April 2020. The utilization of CE with C⁴D in the areas of pharmaceutical, food and biomedical analysis is presented. Finally, concluding remarks and outlooks are discussed.