New approaches of LC-MS compatible method development on α1-acid glycoprotein-based stationary phase for resolution of enantiomers by HPLC

Emerging Developments in Separation Techniques and Analysis of Chiral Pharmaceuticals

Chiral separation, the process of isolating enantiomers from a racemic mixture, holds paramount importance in diverse scientific disciplines. Using chiral separation methods like chromatography and electrophoresis, enantiomers can be isolated and characterized. This study emphasizes the significance of chiral separation in drug development, quality control, environmental analysis, and chemical synthesis, facilitating improved therapeutic outcomes, regulatory compliance, and enhanced industrial processes. Capillary electrophoresis (CE) has emerged as a powerful technique for the analysis of chiral drugs. This review also highlights the significance of CE in chiral drug analysis, emphasizing its high separation efficiency, rapid analysis times, and compatibility with other detection techniques. High-performance liquid chromatography (HPLC) has become a vital technique for chiral drugs analysis. Through the utilization of a chiral stationary phase, HPLC separates enantiomers based on their differential interactions, allowing for the quantification of individual enantiomeric concentrations. This study also emphasizes the significance of HPLC in chiral drug analysis, highlighting its excellent resolution, sensitivity, and applicability. The resolution and enantiomeric analysis of nonsteroidal anti-inflammatory drugs (NSAIDs) hold great importance due to their chiral nature and potential variations in pharmacological effects. Several studies have emphasized the significance of resolving and analyzing the enantiomers of NSAIDs. Enantiomeric analysis provides critical insights into the pharmacokinetics, pharmacodynamics, and potential interactions of NSAIDs, aiding in drug design, optimization, and personalized medicine for improved therapeutic outcomes and patient safety. Microfluidics systems have revolutionized chiral separation, offering miniaturization, precise fluid control, and high throughput. Integration of microscale channels and techniques provides a promising platform for on-chip chiral analysis in pharmaceuticals and analytical chemistry. Their applications in techniques such as high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC) offer improved resolution and faster analysis times, making them valuable tools for enantiomeric analysis in pharmaceutical, environmental, and biomedical research.

Progress in Chiral Stationary Phases Based on Proteins and Glycoproteins

A lot of chiral stationary phases (CSPs) have been introduced for the purpose of analytical and preparative separations of enantiomers. CSPs based on proteins and glycoproteins have unique properties among those CSPs. This review article deals with the preparation of CSPs based on proteins and glycoproteins, their chiral recognition properties and mechanisms, focusing on the CSPs investigated in our group. The dealt proteins and glycoproteins are including bovine serum albumin, human serum albumin, lysozyme, pepsin, human α₁-acid glycoprotein (AGP), chicken ovomucoid and chicken ovoglycoprotein (named chicken AGP).

Simultaneous enantio- and diastereo-selective high-performance liquid chromatography separation of paroxetine on an immobilized amylose-based chiral stationary phase under green reversed-phase conditions

A simple and green high-performance liquid chromatography method for the separation of paroxetine from its enantiomeric and diastereomeric impurities has been developed. The simultaneous chromatographic resolution was carried out on the amylose-based Chiralpak IA-3 chiral stationary phase using the mixture ethanol-water-diethylamine 80:20:0.1 (v/v/v) as a mobile phase. The effects of substitution of ethanol with methanol or acetonitrile and changes in column temperature on selectivity have been carefully investigated. The optimized single-run HPLC protocol allows the baseline separation of the enantiomers of paroxetine without suffering from interference from five other chiral and achiral impurities reported in the monograph of the European Pharmacopoeia.

Enantiomeric methadone quantitation on real post-mortem dried matrix spots samples: Comparison of liquid chromatography and supercritical fluid chromatography coupled to mass spectrometry

This study describes two bioanalytical methods for the quantitation of the two methadone enantiomers in dried matrix spots using high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) and high performance supercritical chromatography tandem mass spectrometry (HPSFC-MS/MS). Dried matrix spots were obtained by spotting 10 µL of each sample fluid on a Whatman paper. Methadone and its main metabolite, EDDP, were extracted with 100 µL methanol and subsequently injected into the LC-MS/MS and SFC-MS/MS systems. Enantiomeric separation was achieved with AGP-column for the LC conditions and with Chiralpak IH-3 in SFC. The two methods were fully validated and 93 post-mortem samples were analysed with both analytical methods. Results from validation parameters and results obtained for all post-mortem samples were compared with a significant spearman correlation of r_s = 0.9978 for R-methadone and r_s = 0.9981 for S-methadone. The LC method provided better results in terms of uncertainty, retention factor and resolution, whereas SFC provides better sensitivity, with lower LOD. Median R-/S-methadone ratio in peripheral blood was found equal to 1.60 (N = 32), varying from 0.79 to 4.23. The reported values were in good agreement with previously published results. Based on the results obtained here, SFC-MS/MS can be considered a reliable alternative to the widely used LC-MS/MS for the quantitation of methadone enantiomers in bioanalysis and should be evaluated for other bioanalytical methods. Both methods can be easily and quickly used in toxicological routine analysis for the methadone quantitation in human fluids matrices, even if considering that the polysaccharide coated column IH-3 used in SFC does not allow the enantiomeric EDDP separation.

Chiral separation and molecular simulation study of six antihistamine agents on a coated cellulose tri-(3,5-dimethylphenycarbamate) column (Chiralcel OD-RH) and its recognition mechanisms

Enantiomeric separation of six antihistamine agents was first systematically investigated on a cellulose-based chiral stationary phase (CSP), that is, cellulose tris-(3,5-dimethyl phenyl carbamate) (Chiralcel OD-RH), under the reversed-phase mode. Orphenadrine, meclizine, terfenadine, dioxopromethazine, and carbinoxamine enantiomers were completely separated under the optimized mobile phase conditions with resolutions of 5.02, 1.93, 1.68, 1.67, and 1.54, respectively. Mequitazine was partially separated with a resolution of 0.77. The influences of type and concentration of buffer salt, the pH of buffer solution, and the type and ratio of organic modifier on the chiral separation were evaluated and optimized. For a better insight into the enantiorecognition mechanisms, molecular docking was carried out via the Autodock software. The lowest binding energy and the optimal conformations of the analytes/CSP complexes were supplied, and the mechanisms of chiral recognition were determined. According to the results, the key interactions for the chiral recognition of these six analytes on CDMPC were π-π interactions, hydrophobic interactions, hydrogen bond interactions, and some special interactions.

Enantiomeric Separation of Dioxopromethazine and its Stereoselective Pharmacokinetics in Rats by HPLC-MS/MS

Dioxopromethazine (DPZ) is a popular phenothiazine antihistamine that is widely used as a racemic drug in clinical to cure respiratory illness. In our work, a reliable, specific, and rapid enantioselective HPLC-MS/MS method has been established and fully validated for the quantification of R- and S-DPZ in rat plasma. After plasma alkalization (with 1 M Na₂CO₃), DPZ enantiomers and diphenhydramine (IS) were extracted using ethyl acetate. Completely separation of R- and S-DPZ (Rs = 2.8) within 12 min was implemented on Chiralpak AGP column (100 × 4.0 mm i.d., 5 μm) employing ammonium acetate (10 mM; pH 4.5) - methanol (90:10, v/v) as mobile phase. Themultiple reaction monitoring (MRM) mode was used for the detection of DPZ enantiomers and IS. The transitions of m/z 317.2 → 86.1 and 256.2 → 167.1 werechosen for monitoring DPZ enantiomers and IS, respectively. Good linearity (r² > 0.995) was achieved for each DPZ enantiomer over the linear ranges of 1.00 - 80.00 ng/mL, with the lower limit of quantitation (LLOQ) of 1.00 ng/mL. The intra-day and inter-day precisions (RSDs,%) were below 12.3%, and accuracies (REs,%) were in the scope of-10.5% to 6.6%, which were within the admissible criteria. The validated bioanalytical approach was applied to the stereoselective pharmacokinetic (PK) research of DPZ in rat plasma for the first time. It was found that significant differences (p < 0.05) exist between the main PK parameters of R- and S-DPZ, indicating the pharmacokinetic behaviors of DPZ enantiomers in rats were stereoselective. The chiral inversion of the enantiomers did not occur during the assay.

Simultaneous enantioselective determination of seven psychoactive drugs enantiomers in multi-specie animal tissues with chiral liquid chromatography coupled with tandem mass spectrometry

In stock farming, illegal use of antipsychotics has caused the food safety problem. This paper presents for the first time, a multi-residues method for the simultaneous enantioselective determination of seven antipsychotics in pork, beef and lamb muscles. The behaviors of Chiralpak AGP toward changes in pH and organic modifier in mobile phase were studied, and all analytes were rapidly separated within 30 min. The calibration curves of all enantiomers were linear in the range of 1-250 ng g^-1, with correlation coefficient above 0.9931. The recoveries of the targeted compounds were higher than 82.1%, with repeatability and intermediate precision lower than 18.2% and 17.4%, respectively. In three matrices, the limit of detection and limit of quantification ranged from 0.20 to 0.65 ng g^-1 and from 0.40 to 1.00 ng g^-1, respectively. The proposed method can be used to provide additional information for the reliable risk assessment of chiral antipsychotics.

Multi-residue enantiomeric analysis of human and veterinary pharmaceuticals and their metabolites in environmental samples by chiral liquid chromatography coupled with tandem mass spectrometry detection

Enantiomeric profiling of chiral pharmacologically active compounds (PACs) in the environment has hardly been investigated. This manuscript describes, for the first time, a multi-residue enantioselective method for the analysis of human and veterinary chiral PACs and their main metabolites from different therapeutic groups in complex environmental samples such as wastewater and river water. Several analytes targeted in this paper have not been analysed in the environment at enantiomeric level before. These are aminorex, carboxyibuprofen, carprofen, cephalexin, 3-N-dechloroethylifosfamide, 10,11-dihydro-10-hydroxycarbamazepine, dihydroketoprofen, fenoprofen, fexofenadine, flurbiprofen, 2-hydroxyibuprofen, ifosfamide, indoprofen, mandelic acid, 2-phenylpropionic acid, praziquantel and tetramisole. The method is based on chiral liquid chromatography utilising a chiral α1-acid glycoprotein column and tandem mass spectrometry detection. Excellent chromatographic separation of enantiomers (Rs≥1.0) was achieved for chloramphenicol, fexofenadine, ifosfamide, naproxen, tetramisole, ibuprofen and their metabolites: aminorex and dihydroketoprofen (three of four enantiomers), and partial separation (Rs = 0.7-1.0) was achieved for ketoprofen, praziquantel and the following metabolites: 3-N-dechloroethylifosfamide and 10,11-dihydro-10-hydroxycarbamazepine. The overall performance of the method was satisfactory for most of the compounds targeted. Method detection limits were at low nanogram per litre for surface water and effluent wastewater. Method intra-day precision was on average under 20% and sample pre-concentration using solid phase extraction yielded recoveries >70% for most of the analytes. This novel, selective and sensitive method has been applied for the quantification of chiral PACs in surface water and effluent wastewater providing excellent enantioresolution of multicomponent mixtures in complex environmental samples. It will help with better understanding of the role of individual enantiomers in the environment and will enable more accurate environmental risk assessment.

Retarded photooxidation of cyamemazine in biomimetic microenvironments

Cyamemazine (CMZ) is a neuroleptic drug that mediates cutaneous phototoxicity in humans. Here, the photobehavior of CMZ has been examined within α1 -acid glycoproteins, β- and γ-cyclodextrins and SDS micelles. In all these microenvironments, CMZ emission was enhanced and blue-shifted, and its lifetime was longer. Irradiation of the entrapped drug at 355 nm, under air; led to the N,S-dioxide. Within glycoproteins or SDS micelles the reaction was clearly slower than in phosphate buffered solution (PBS); protection by cyclodextrins was less marked. Transient absorption spectroscopy in PBS revealed formation of the triplet state ((3)CMZ*) and the radical cation (CMZ(+•)). Upon addition of glycoprotein, the contribution of CMZ(+•) became negligible, whereas (3)CMZ* dominated the spectra; in addition, the triplet lifetime became considerably longer. In cyclodextrins, this occurred to a lower extent. In all microheterogeneous systems, quenching by oxygen was slower than in solution; this was most remarkable inside glycoproteins. The highest protection from photooxidation was achieved inside SDS micelles. The results are consistent with photooxidation of CMZ through photoionization and subsequent trapping of the resulting radical cation by oxygen. This reaction is extremely sensitive to the medium and constitutes an appropriate probe for localization of the drug within a variety of biological compartments.

Recentchiral selectors for separation in HPLC and CE

Enantiomers (stereoisomers) can exhibit substantially different properties if present in chiral environments. Since chirality is a basic property of nature, the different behaviors of the individual enantiomers must be carefully studied and properly treated. Therefore, enantioselective separations are a very important part of separation science. To achieve the separation of enantiomers, an enantioselective environment must be created by the addition of a chiral selector to the separation system. Many chiral selectors have been designed and used in various fields, such as the analyses of drugs, food constituents and agrochemicals. The most popular have become the chiral selectors and/or chiral stationary phases that are of general use, i.e., are applicable in various separation systems and allow for chiral separation of structurally different compounds. This review covers the most important chiral selectors / chiral stationary phases described and applied in high performance liquid chromatography and capillary electrophoresis during the period of the last three years (2008–2011).