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This work reviews the literature of chiral capillary electrokinetic chromatography from January 2016 to March 2021. This is done to explore the state-of-the-art approach and recent developments carried out in this field. The separation principle of the technique is described and supported with simple graphical illustrations, showing migration under normal and reversed polarity modes of the separation voltage. The most relevant applications of the technique for enantioseparation of drugs and other enantiomeric molecules in different fields using chiral selectors in single, dual, or multiple systems are highlighted. Measures to improve the detection sensitivity of chiral capillary electrokinetic chromatography with UV detector are discussed, and the alternative aspects are explored, besides special emphases to hyphenation compatibility to mass spectrometry. Partial filling and counter migration techniques are described. Indirect identification of the separated enantiomers and the determination of enantiomeric migration order are mentioned. The application of Quality by Design principles to facilitate method development, optimization, and validation is presented. The elucidation and explanation of chiral recognition in molecular bases are discussed with special focus on the role of molecular modeling.

This review is dedicated to sustainable practices in liquid chromatography. HPLC and UHPLC methods contribute significantly to routine analytical techniques. Therefore, the transfer of classical liquid chromatographic methods into sustainable ones is of utmost importance in moving toward sustainable development goals. Among other principles to render a liquid chromatographic method green, the substitution of the organic solvent component in the mobile phase with a greener one received great attention. This review concentrates on choosing the best alternative green organic solvent to replace the classical solvent in the mobile phase for easy, rapid transfer to a more sustainable normal phase or reversed-phase liquid chromatography. The main focus of this review will be on describing the transfer of non-green to green and white chromatographic methods in an effort to elevate sustainability best practices in analytical chemistry. The greenness properties and greenness ranking, in addition to the chromatographic suitability of seventeen organic solvents for liquid chromatography, are mentioned to have a clear insight into the issue of rapidly choosing the appropriate solvent to transfer a classical HPLC or UHPLC method into a more sustainable one. A simple guide is proposed for making the liquid chromatographic method more sustainable.

Loratadine (LoR) is a highly lipophilic and practically insoluble in water, hence having a low oral bioavailability. As it is formulated as topical gel, it competitively binds with the receptors, thus reducing the side-effects. The objective of this study was to prepare LoR loaded nanosponge (LoR-NS) in gel for topical delivery. Nine different formulations of emulsion were prepared by solvent evaporation method with polyvinyl alcohol (PVA), ethyl cellulose (EC), and dichloromethane (DCM). Based on 3 2 Full Factorial Design (FFD), optimization was carried out by varying the concentration of LOR:EC ratio and stirring rate. The preparations were subjected for the evaluation of particle size (PS), in vitro release, zeta potential (ZP) and entrapment efficiency (EE). The results revealed that the NS dispersion was nanosized with sustained release profiles and significant PS. The optimised formulation was formulated and incorporated into carbopol 934P hydrogel. The formulation was then examined to surface morphological characterizations using scanning electron microscopy (SEM) which depicted spherical NS. Stability studies, undertaken for 2 months at 40 ± 2 °C/75 ± 5% RH, concluded to the stability of the formulation. The formulation did not cause skin irritation. Therefore, the prepared NS hydrogel proved to be a promising applicant for LoR as a novel drug delivery system (NDDS) for safe, sustained and controlled topical application.

A green liquid chromatographic method is considered in this work to minimize the environmental impact of waste solvents. One important principle is to replace or eliminate the use of hazardous organic solvents. Organic impurities in any active pharmaceutical ingredient could arise either during the process of its synthesis, or as degradation products developed throughout the shelf-life. Remdesivir (RDS) is an antiviral drug, approved by the US Food and Drug Adminstration (-FDA), to treat SARS-Cov-2 virus during its pandemic crisis. We studied the stability of remdesivir against several degradation pathways using the organic solvent-free liquid chromatographic technique. Separation was performed on RP-C18 stationary phase using mixed-micellar mobile phase composed of a mixture of 0.025 M Brij-35, 0.1 M sodium lauryl sulfate (SLS), and 0.02 M disodium hydrogen phosphate, adjusted to pH 6.0. The mobile phase flow rate was 1 mL min−1, and detection was carried out at a wavelength of 244 nm. We profiled the impurities that originated in mild to drastic degradation conditions. The method was then validated according to International Conference of Harmonization (ICH) guidelines within a linearity range of 5–100 μg mL−1 and applied successfully for the determination of the drug in its marketed dosage form. A brief comparison was established with reported chromatographic methods, including a greenness assessment on two new metrics (GAPI and AGREE). This study is the first to be reported as eco-friendly, solvent-free, and stability indicating LC methodology for RDS determination and impurity profiling.

Analytical-method development based on design of experiment has been applied for optimizing the enantioseparation of amlodipine by chiral capillary electrokinetic chromatography using maltodextrin as the chiral selector. The effect of different factors on the enantioresolution quality was screened. Three separation factors, namely maltodextrin concentration, pH of the background electrolyte and applied voltage were selected as independent variables. The number of experiments was reduced while maximizing the information content using design of experiment. Based on a full-quadratic design that included three variables on three levels, the total design space could be reduced to fifteen factor combinations using a D-optimal algorithm. The aim of the experiment was to find the optimal factor combinations with respect to resolution. The maltodextrin concentration (7.5–10% w/v) demonstrated the strongest effect on the resolution followed by pH (2–4) of the background electrolyte and the applied voltage (15–20 kV). An increase in the maltodextrin concentration was found to result in a greater stereoselectivity, represented by the higher resolution values (Rs ≥ 1.5). The separation conditions in the proposed method were feasible to be adjusted within the applied range with an acceptable resolution.

In the current study, the Prussian blue analog decorated with zinc oxide (PBA@ZnO) was produced using a simple chemical co-precipitation method. The nanohybrid was examined using XRD, EDX, SEM, and TEM techniques, where it exhibited a polycrystalline structure with highly intense broadening peaks. The surface morphology was observed as thin nanosheets decorated with tiny spheres. Following excitation at 360 nm, the fluorescence spectra of PBA@ZnO showed fluorescence emission at 455 nm. The developed PBA@ZnO was used to qualitatively and quantitatively assess sunset yellow (SY), where its native fluorescence was selectively quenched as SY concentrations increased. For the first time, PBA@ZnO was used as a turn-off nano-sensor for the spectrofluorimetric measurement of SY. The method’s markable sensitivity was demonstrated within an SY linearity range of 50–500 ng/mL, where the limit of detection was calculated as 9.77 ng/mL. Real sample analysis in the food industry, including samples from real food, soft drinks, and sun cream, was made possible by the detection of tiny amounts of SY. Analytical Greenness (AGREE), AGREEprep, and the complementing Green Analytical Procedure Index (Complex MoGAPI) were used to illustrate the new approach’s exceptional eco-friendliness and greenness. The RGB 12 algorithm worked to demonstrate that the suggested approach is less costly, more environmentally friendly, more sustainable, analytically sound, and whiter than the ones that were previously published. In accordance with ICH principles, the suggested method was validated. This approach offers a promising way to rapidly and accurately identify and measure SY in the food industry, helping to guarantee food safety and maintain the health of customers.

Chondroitin sulfate A was covalently immobilized onto a monolithic silica epoxy column involving a Schiff base formation in the presence of ethylenediamine as a spacer and evaluated in terms of its selectivity in enantioseparation. The obtained column was utilized as a chiral stationary phase in enantioseparation of amlodipine and verapamil using a mobile phase consisting of 50 mM phosphate buffer pH 3.5 and UV detection. Sample dilution by organic solvents (preferably 25% v/v acetonitrile-aqueous solution) was applied to achieve baseline enantioresolution (Rs > 3.0) of the individual drug models within 7 min, an excellent linearity (R2 = 0.999) and an interday repeatability of 1.1% to 1.8% RSD. The performance of the immobilized column for quantification of racemate in commercial tablets showed a recovery of 86–98% from tablet matrices. Computational modeling by molecular docking was employed to investigate the feasible complexes between enantiomers and the chiral selector.

HPLC stationary phases of monolithic and fused core type can be used to achieve fast chromatographic separation as an alternative to UPLC. In this study, monolithic and fused core stationary phases are compared for fast separation of four fat-soluble vitamins. Three new methods on the first and second generation monolithic silica RP-18e columns and a fused core pentafluoro-phenyl propyl column were developed. Application of three fused core columns offered comparable separations of retinyl palmitate, DL-α-tocopheryl acetate, cholecalciferol and menadione in terms of elution speed and separation efficiency. Separation was achieved in approx. 5 min with good resolution (R > 5) and precision (RSD ≤ 0.6 %). Monolithic columns showed, however, a higher number of theoretical plates, better precision and lower column backpressure than the fused core column. The three developed methods were successfully applied to separate and quantitate fat-soluble vitamins in commercial products.

Two different concepts for developing direct HPLC-UV methods for quantifying fosfomycin trometamol were developed without any derivatization and modification of the analyte. In the first concept, without the use of alkylamines as ion-pairs in the mobile phase, by using cyanopropyl CN and a strong anion-exchanger column, we investigated the possibility of their highly polar and anion-exchanging forces and mechanisms to retain, separate and detect trometamol without the help of additional agents or modifiers. In the second concept, the most frequent reversed-phase C18 columns with different characteristics and vendors were tested in combination with different length-based alkylamines with 3–10 C atoms in their chains. In our research, we found that the ion-pairing of fosfomycin with 6–10 C-atom-based alkyl-length of aliphatic chains manifested the most appropriate strength of interactions between alkyl-paired trometamol molecules and octadecylsilane or C18 bonded RP column to achieve optimal retention, selectivity and peak shape on chromatograms, with the possibility for the fine-tuning of elution time. The simplicity of our method concept omits the need for expensive and sophisticated columns like HILIC, C30 graphite carbon, and mixed-mode-based columns for easier retaining, separation, and determination of fosfomycin, and for its quantification purposes, especially in high-throughput analyses in regular quality-control laboratories.

A capillary zone electrophoresis method was developed for the determination of NiII(3-OMe-salophene), a substance with anticancer activity in vitro. A fused silica capillary (56 cm × 100 µm) was used for this purpose. The method was optimized in terms of parameters affecting the electrophoretic conditions in order to optimize separation efficiency and total time of migration. The analysis was best performed using an operating buffer of 50 mM borate, adjusted to pH 9.3, mixed with acetonitrile (50%, v/v) as organic modifier. Injections were performed hydrodynamically by applying a pressure of 50 mbar for 8 s, and a 30 kV separation voltage was selected at 25 °C. Detection was carried out at 250 nm using diode array detector (DAD). The method allowed the separation of NiII(3-OMe-salophene) from four other structurally related impurities in a total migration time (tm) of 8 min. Peak identification was achieved using the standard reference of individual impurities. The purity of the migrated NiII(3-OMe-salophene) was confirmed by Ultra-violet (UV) scan overlay depending on DAD. The linear ranges for the determination of NiII(3-OMe-salophene) was 400–20,000 ng mL−1 with limit of detection (LOD) of 120 ng mL−1. Acceptable intra-day and inter-day precisions were achieved (%relative standard deviation (RSD) results were less than 0.76% and 0.30%, respectively). The proposed method was assessed for greenness and compared to reported methodologies to prove superiority.