Online sample concentration in partial-filling chiral electrokinetic chromatography – mass spectrometry

Enantiomeric Analysis of Chiral Drugs Using Mass Spectrometric Methods: A Comprehensive Review

Chirality plays a crucial role in the drug development process, influencing fundamental chemical and biochemical processes and significantly affecting our daily lives. This review provides a comprehensive examination of mass spectrometric (MS) methods for the enantiomeric analysis of chiral drugs. It thoroughly investigates MS-hyphenated techniques, emphasizing their critical role in achieving enantioselective analysis. Furthermore, it delves into the intricate chiral recognition mechanisms inherent in MS, elucidating the fundamental principles that govern successful chiral separations. By critically assessing the obstacles and potential benefits associated with each MS-based method, this review offers valuable insights for researchers navigating the complexities of chiral analysis. Both qualitative and quantitative approaches are explored, presenting a comparative analysis of their strengths and limitations. This review is aimed at significantly enhancing the understanding of chiral MS methods, serving as a crucial resource for researchers and practitioners engaged in enantioselective studies.

From capillaries to microchips, green electrophoretic features for enantiomeric separations: A decade review (2013-2022)

Enantioseparation by the electromigration-based method is well-established and widely discussed in the literature. Electrophoretic strategies have been used to baseline resolve complex enantiomeric mixtures, typically using a selector substance into the background electrolyte (BGE) from capillaries to microchips. Along with developing new materials/substances for enantioseparations, it is the concern about the green analytical chemistry (GAC) principles for method development and application. This review article brings a last decade's update on the publications involving enantioseparation by electrophoresis for capillary and microchip systems. It also brings a critical discussion on GAC principles and new green metrics in the context of developing an enantioseparation method. Chemical and green features of native and modified cyclodextrins are discussed. Still, given the employment of greener substances, ionic liquids and deep-eutectic solvents are highlighted, and some new selectors are proposed. For all the mentioned selectors, green features about their production, application, and disposal are considered. Sample preparation and BGE composition in GAC perspective, as well as greener derivatization possibilities, were also addressed. Therefore, one of the goals of this review is to aid the electrophoretic researchers to look where they have not.

Quantitative analysis of drug distribution in heterogeneous tissues using dual-stacking capillary electrophoresis-mass spectrometry

BACKGROUND AND PURPOSE

Intratumour heterogeneity frequently leads to drug resistance, which is a major issue in drug discovery. Drug distribution is one of the key factors for elucidating the resistance mechanism; however, quantitative and regional drug measurement is challenging. Here, we developed a novel ultra-sensitive analytical method and applied it to HER3-targeting antibody-drug conjugate patritumab deruxtecan (HER3-DXd), aiming to explore its payload (DXd) distribution within heterogeneous tissues.

EXPERIMENTAL APPROACH

The developed analytical method is named LDMS-CE-MS, a capillary electrophoresis-mass spectrometry (CE-MS) coupled with a novel sample preconcentration/separation method called "large-volume dual-sample stacking by micelle collapse and sweeping (LDMS)". First, the analytical performance of LDMS-CE-MS for DXd detection was evaluated. Subsequently, we evaluated the bystander effect of HER3-DXd, where tumour tissues were excised from xenograft models and clinical specimens after administration of HER3-DXd. HER3-high expression, adjacent, and HER3-low expression regions were then sampled by laser microdissection to quantify the released DXd.

KEY RESULTS

LDMS concentrated DXd by 1000-fold and separated it from the hydrophilic bio-matrix through continuous capture and release by the charged micelles, allowing quantification at sub-attomole-level. DXd concentrations decreased in the order of antigen-high expression > adjacent > antigen-low expression regions in the tumour xenograft model, whereas in clinical specimens, adjacent and antigen-high expression regions had approximately the same concentration. These distributions represent a bystander effect.

CONCLUSIONS AND IMPLICATIONS

Our LDMS-CE-MS successfully visualized the attomole-level drug distributions in heterogeneous clinical specimens. This new platform opens a new era of quantitative pharmacokinetic analysis, facilitating drug discovery and development.

Capillary Electrophoresis Mass Spectrometry: Developments and Applications for Enantioselective Analysis from 2011–2020

It is now more than 25 years since the first report of enantioselective analysis by capillary electrophoresis-mass spectrometry (CE-MS) appeared. This article reviews the power of chiral CE-MS in resolving issues on the use of chiral selector incompatibility with MS and poor detectability encountered for chiral compounds by UV detection. The review begins with the general principles, requirements, and critical aspects of chiral CE-MS instrumentation. Next, the review provides a survey of MS-compatible chiral selectors (CSs) reported during the past decade, and the key achievements encountered in the time period using these CSs. Within the context of the strategies used to combine CE and MS, special attention is paid to the approaches that feature partial filling technique, counter-migration techniques, and direct use of CS, such as molecular micelles. In particular, the development and application of moving and fixed CS for EKC-MS, MEKC-MS, and CEC-MS demonstrate how various chiral compounds analyses were solved in a simple and elegant way during the 2010–2020 review period. The most noteworthy applications in the determination of chiral compounds are critically examined. The operating analytical conditions are detailed in the Tables, and the authors provide commentary on future trends of chiral separations by CE-MS.

Chiral Capillary Electrokinetic Chromatography: Principle and Applications, Detection and Identification, Design of Experiment, and Exploration of Chiral Recognition Using Molecular Modeling

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.

Chiral Selectors in Capillary Electrophoresis: Trends During 2017⁻2018

Chiral separation is an important process in the chemical and pharmaceutical industries. From the analytical chemistry perspective, chiral separation is required for assessing the fit-for-purpose and the safety of chemical products. Capillary electrophoresis, in the electrokinetic chromatography mode is an established analytical technique for chiral separations. A water-soluble chiral selector is typically used. This review therefore examines the use of various chiral selectors in electrokinetic chromatography during 2017–2018. The chiral selectors were both low and high (macromolecules) molecular mass molecules as well as molecular aggregates (supramolecules). There were 58 papers found by search in Scopus, indicating continuous and active activity in this research area. The macromolecules were sugar-, amino acid-, and nucleic acid-based polymers. The supramolecules were bile salt micelles. The low molecular mass selectors were mainly ionic liquids and complexes with a central ion. A majority of the papers were on the use or preparation of sugar-based macromolecules, e.g., native or derivatised cyclodextrins. Studies to explain chiral recognition of macromolecular and supramolecular chiral selectors were mainly done by molecular modelling and nuclear magnetic resonance spectroscopy. Demonstrations were predominantly on drug analysis for the separation of racemates.

Derivatisation for separation and detection in capillary electrophoresis (2015-2017)

Derivatisation is an integrated part of many analytical workflows to enable separation and detection of the analytes. In CE, derivatisation is adapted in the four modes of pre-capillary, in-line, in-capillary, and post-capillary derivatisation. In this review, we discuss the progress in derivatisation from February 2015 to May 2017 from multiple points of view including sections about the derivatisation modes, derivatisation to improve the analyte separation and analyte detection. The advancements in derivatisation procedures, novel reagents, and applications are covered. A table summarising the 46 reviewed articles with information about analyte, sample, derivatisation route, CE method and method sensitivity is provided.

Recent progress of sample stacking in capillary electrophoresis (2014-2016)

The term "sample stacking" comprises a relatively broad spectrum of techniques that already form an almost inherent part of the methodology of CZE. Their principles are different but the effect is the same: concentration of a diluted analyte into a narrow zone and considerable increase of the method sensitivity. This review brings a survey of papers on electrophoretic sample stacking published approximately since the second quarter of 2014 till the first quarter of 2016. It is organized according to the principles of the stacking methods and includes chapters aimed at the concentration adjustment principle (Kohlrausch stacking), techniques based on pH changes, micellar methods, and other stacking techniques. Not reviewed are papers on transient ITP that are covered by another review in this issue.

Chiral Capillary Electrophoresis-Mass Spectrometry: Developments and Applications in the Period 2010-2015: A Review

The sensitive detection of chiral compounds by capillary electrophoresis (CE) in biological samples remains a significant challenge and is currently considered a bottleneck in many chiral analysis projects. Chiral CE-MS can significantly improve the limit of detection and provide high sensitivity compared with chiral CE-UV. Chiral selectors such as modified cyclodextrins (CDs) and polymeric surfactants (a.k.a. molecular micelles, M_oM_s) in electrokinetic chromatography (EKC), micellar electrokinetic chromatography (MEKC) and capillary electrochromatography (CEC) have been developed to address the need for high sensitivity by CE-MS. However, several problems remain to be investigated to fully understand the potential of these hyphenation modes. This review provides introduction to major chiral CE-MS modes for the novice and highlights the important working principles of each mode of chiral CE-MS. Next, recent practical developments and progress in chiral CE-MS dating from January 2010 to September 2015 are described. The achievements in clinical and biomedical sciences using a variety of chiral selectors such as CDs and M_oM_s in EKC-MS, MEKC-MS and CEC-MS are discussed. Finally, conclusions and future prospects of CE-MS in chiral analysis are drafted.

Recent applications of CE- and HPLC-MS in the analysis of human fluids

The present review intends to cover the literature on the use of CE-/LC-MS for the analysis of human fluids, from 2010 until present. It has been planned to provide an overview of the most recent practical applications of these techniques to less extensively used human body fluids, including, bronchoalveolar lavage fluid, synovial fluid, nipple aspirate, tear fluid, breast fluid, amniotic fluid, and cerumen. Potential pitfalls related to fluid collection and sample preparation, with particular attention to sample clean-up procedures, and methods of analysis, from the research laboratory to a clinical setting will also be addressed. While being apparent that proteomics/metabolomics represent the most prominent approaches for global identification/quantification of putative biomarkers for a variety of human diseases, evidence is also provided of the suitability of these sophisticated techniques for the detection of heterogeneous components carried by these fluids.

Improving the sensitivity in chiral capillary electrophoresis

CE is known for being one of the most powerful analytical techniques when performing enantioseparations due to its numerous advantages such as excellent separation efficiency and extremely low solvents and reagents consumption, all of them derived from the capillary small dimensions. Moreover, it is worth highlighting that unlike in chromatographic techniques, in CE the chiral selector is generally within the separation medium instead of being attached to the separation column which makes the method optimization a more versatile task. Despite its numerous advantages, when using UV-Vis detection, CE lacks of sensitivity detection due to its short optical path length derived from the narrow separation capillary. This issue can be overcome by means of different approaches, either by sample treatment procedures or by in-capillary preconcentration techniques or even by employing detection systems more sensitive than UV-Vis, such as LIF or MS. The present review assembles the latest contributions regarding improvements of sensitivity in chiral CE published from June 2013 until May 2015, which follows the works included in a previous review reported by Sánchez-Hernández et al. [Electrophoresis 2014, 35, 12-27].

Cyclodextrins in capillary electrophoresis: recent developments and new trends

Despite the fact that extensive research in the field of separations by capillary electrophoresis (CE) has been carried out and many reviews have been published in the last years, a specific review on the use and future potential of cyclodextrins (CDs) in CE is not available. This review focuses the attention in the CD-CE topic over the January 2013-February 2014 period (not covered by previous more general CE-reviews). Recent contributions (reviews and research articles) including practical uses (e.g. solute-CD binding constant estimation and further potentials; 19% of publications), developments and applications (mainly chiral and achiral analysis; 38 and 24% of publications, respectively) are summarized in nine comprehensive tables and are commented. Statistics and predictions related to the CD-CE publications are highlighted in order to infer the current and expected research interests. Finally, trends and initiatives on CD-CE attending to real needs or practical criteria are outlined.