Recent developments in CE and CEC of peptides (2009-2011)

The review brings a comprehensive survey of the recent developments of high-performance electroseparation methods in capillary and microchip formats: zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography and electrochromatography. Applications of these techniques to analysis, isolation, purification and physicochemical and biochemical characterization of peptides are described. Advances in the investigation of electromigration properties of peptides, and in the methodology of their analysis, such as sample preparation, adsorption suppression, EOF control and detection, are presented. New developments, in particular, CE and CEC modes are reported and several types of their applications to peptide analysis are described: conventional qualitative and quantitative analysis, determination in complex (bio)matrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid, sequence and chiral analysis, and peptide mapping of proteins. Some micropreparative peptide separations are shown and capabilities of CE and CEC techniques to provide relevant physicochemical characteristics of peptides are demonstrated.     

Recent developments in capillary and microchip electroseparations of peptides (2017–mid 2019)

The review presents a comprehensive survey of recent developments and applications of high performance capillary and microchip electroseparation methods (zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography) for analysis, micropreparation, and physicochemical and biochemical characterization of peptides since 2017 up to about the middle of 2019. Progress in the study of electromigration properties of peptides and in the methodology of their analysis (sample preseparation, preconcentration and derivatization, adsorption suppression, EOF control, and detection) are described. Advances in CE and CEC methods are demonstrated and their applications in the following areas are presented: qualitative and quantitative analysis, determination in complex (bio)matrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid, sequence and chiral analysis, and peptide mapping of proteins. In addition, micropreparative separations and determinations of important physicochemical characteristics of peptides by CE and CEC methods are reported.     

Recent applications of capillary electromigration methods to separation and analysis of proteins

This review article describes the significant recent developments in analysis of proteins by capillary electromigration (CE) methods (zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography and electrochromatography) during the period 2011–2015. Improvements in sample preparation, preconcentration, suppression of adsorption and control of electroosmotic flow, separations by particular CE methods, and the detection schemes used in the analysis of proteins are discussed. Innovative applications of the above CE methods for quality control of protein biopharmaceuticals, protein determination in complex biomatrices, peptide mapping of proteins, and determination of physicochemical parameters of proteins are presented.     

Recent advances in peptide and peptidomimetic stereoisomer separations by capillary electromigration techniques

As the stereochemistry of peptides determines their physicochemical properties and biological activities, analytical methods able to discriminate between peptide stereoisomers are important especially with regard to pharmaceutical peptides and peptidomimetics. The present review summarizes recent developments in peptide and peptidomimetic stereoisomer separations by capillary electromigration techniques. The majority of separations were performed by CE while only few reports have been published on the subject of electrochromatography. In addition to systematic studies on the applicability of certain buffer additives and the evaluation of specific experimental conditions, there have been attempts to understand the mechanistic aspects of peptide stereoisomer separations as well as to analyze the structure of peptide-CD complexes.     

Enantioseparations in capillary electromigration techniques: recent developments and future trends

This review summarizes the current status of enantioseparations using capillary electromigration techniques and gives the authors insights on the selected fundamental aspects and future trends in this field. The most recent developments in the field of chiral separations using capillary electrophoresis (CE) and capillary electrochromatography (CEC) are summarized. The status of chiral electromigration techniques is evaluated tacking into account the most recent developments in related techniques such as chiral HPLC, GC and SFC.     

Recent progress in chiral separation principles in capillary electrophoresis

This review summarizes recent developments in the field of chiral separations by electromigration techniques including capillary zone electrophoresis (CZE), capillary gel electrophoresis (CGE), isotachophoresis (ITP), electrokinetic chromatography (EKC), and capillary electrochromatography (CEC). This overview focuses on the development of new chiral selectors and the introduction of new techniques rather than applications of already established selectors and methods. The mechanisms of the different chiral separation principles are discussed.     

Computer simulation for the convenient optimization of isocratic reversed-phase liquid chromatographic separations by varying temperature and mobile phase strength

The review summarizes the most recent developments in the field of enantioseparation of chiral drugs using capillary electromigration techniques. The basic principles of enantioseparations in CE are discussed. Recent developments in sample introduction, separation and detection in capillary electrophoresis and capillary electrochromatography are summarized. The applications are arbitrarily divided into the following three groups: (a) racemates and artificial mixtures of enantiomers, (b) drug forms and (c) chiral drugs and their metabolites in biological fluids. Among the various techniques involved the relatively new developments such as CEC in aqueous and nonaqueous buffers, on-line CE-MS coupling, etc. are emphasized.     

Developments in sample preparation and separation techniques for the determination of inorganic ions by ion chromatography and capillary electrophoresis.

A review is presented of sample preparation and separation techniques for the determination of inorganic ions by ion chromatography (IC) and capillary electrophoresis (CE). Emphasis has been placed on those sample treatment methods which are specific to inorganic analysis, and the developments in separation methods which are discussed are those which enhance the capabilities of IC and CE to handle complex sample matrices. Topics discussed include solid-phase extraction for sample clean-up and preconcentration, dialytic methods, combustion methods, matrix-elimination IC, electrostatic IC, electrically polarised ion-exchange resins, electromigration sample preparation in CE, chromatographic sample preparation for CE, use of high-ionic strength background electrolytes, buffering of background electrolytes in CE, use of capillary electrochromatography for inorganic determinations, and methods for the manipulation of separation selectivity in both IC and CE. Finally, some possible future trends are discussed.     

Comparative study of capillary electroendosmotic chromatography and electrically assisted gradient nano-liquid chromatography for the separation of peptides

Capillary electroendoendosmotic chromatography (CEC), being a hybrid of high-performance liquid chromatography (HPLC) and capillary electrophoresis, offers considerable changes to enhance column efficiency, speed of analysis and additional selectivity as compared to the parent methods. The analytes are driven by the electroendosmotic flow (EOF) and separated by surface-solute interactions as well as by differences in electromigration. In this paper on the separation of peptides on C18 reversed-phase and mixed-mode (sulphonic acid-n-alkyl) packings in CEC and electrically assisted reversed-phase gradient nano-LC are investigated. It is shown that mixed mode packings generate a higher EOF than reversed-phase packings that is scarcely dependent on the pH of the eluent. Applying a potential in gradient elution reversed-phase nano-LC of peptides shortens the analysis time as compared to separations without a potential. Electrically assisted reversed-phase gradient elution nano-LC is a powerful separation tool for analysis of tryptic digests. Peptides can be successfully resolved in acidic organic mobile phase at pH 2-3 with and without trifluoroacid as ion pairing reagent under isocratic conditions. It is demonstrated that CEC with mixed mode packing and an eluent of pH 2.3 with varying acetonitrile content can be applied to monitor impurities in a synthetic peptide.     

Capillary electrochromatography of peptides and proteins

This paper reviews recent progress in bioanalysis using capillary electrochromatography (CEC), especially in the field of separation of proteins and peptides. Fundamentals of CEC are briefly discussed. Since most of the recent developments on CEC have focused on column technology, i.e., design of new stationary phases and development of new column configurations, we describe here a variety of column architectures along with their advantages and disadvantages. Newly emerged column technologies in CEC for high speed and high efficiency separation are also discussed. Different analytical platforms of CEC such as pressure-assisted CEC or voltage-assisted micro- high-performance liquid chromatography (HPLC), CEC with different detection techniques, CEC on microchip platforms and multidimensional electrochromatography with their applications in peptide and protein analysis are presented.     

Overview of capillary electrophoresis and capillary electrochromatography.

This paper provides an overview on the current status of capillary electrophoresis (CE) and capillary electrochromatography (CEC). The focus is largely on the current application areas of CE where routine methods are now in place. These application areas include the analysis of DNA, clinical and forensic samples, carbohydrates, inorganic anions and metal ions, pharmaceuticals, enantiomeric species and proteins and peptides. More specific areas such the determination of physical properties, microchip CE and instrumentation developments are also covered. The application, advantages and limitations of CEC are covered. Recent review articles and textbooks are frequently cited to provide readers with a source of information regarding pioneering work and theoretical treatments.     

Recent advances in CE and CEC of pollutants

Recent advances in CE and CEC separation, detection and sample preparation/preconcentration methodologies, for the determination of a variety of compounds having current or potential environmental relevance, have been overviewed. The reviewed literature has illustrated the wide range of CE applications available, indicating a continuing interest in CE and CEC in the environmental field. New developments in chip-based CE systems are also discussed.     

Cover Picture: Electrophoresis 11'2011

Issue no. 11 is a regular issue consisting of 17 contributions distributed over 6 distinct parts: Part I is on fundamentals and methodologies containing 4 research articles dealing with electrokinetic transport through nanochannels, electroosmotic flow in polygonal ducts, analysis of complex samples by mass spectrometry using a sample pretreatment by preparative CITP, and CE analysis of inorganic cations in post‐blast residue extracts; Part II has 5 contributions on various aspects of proteomics and proteins including structural analysis of the recombinant therapeutic product rFVIII, electrophoretic characterization of proteins isolated by various extraction methods from ejaculated and capacitated boar sperms, CE separations of proteins using cationic poly(amidoamine) dendrimers, hemoglobin depletion in erythrocyte cytosolic samples, and peptide fractionation by acid pH SDS‐free electrophoresis; Part III is on separations of malignant cells, and particle capture in a droplet using dielectrophoresis; Part IV has two contributions on CEC separations; Part V consists of two papers on genetic variability and amplification; Part VI is on food analysis with one review article on CE applications in food analysis and one research paper on the determination of betaines in vegetable oils by CE‐MS. Thus, issue no. 11 covers many important subjects. Featured articles include: Electrokinetic transport through nanochannels (( 10.1002/elps.201000564 )) Interdigitated comb‐like electrodes for continuous separation of malignant cells from blood using dielectrophoresis (( 10.1002/elps.201000625 )) Experimental study of dielectrophoresis and liquid dielectrophoresis mechanisms for particle capture in a droplet (( 10.1002/elps.201000548 )) Thirty years of capillary electrophoresis in food analysis laboratories: Potential applications (( 10.1002/elps.201000541 ))     

Recent advances in the analysis of antibiotics by CE and CEC

This article reviews the most recent developments concerning the determination of antibiotics by CE and CEC. The most employed CE separation modes were CZE and MEKC although microemulsion electrokinetic capillary chromatoghraphy was also employed. For the first time, CE was coupled to MS that was applied as a specific and confirmatory detection technique for the analysis of antibiotics. The analytical characteristics of the developed methodologies as well as the different applications reported in the literature on this subject from June 2005 until May 2007 are included in this article. To give the most relevant information on this topic, the experimental conditions employed to achieve the analysis of antibiotics by CE and CEC are provided together with the main applications performed in the pharmaceutical, agrochemical, biological, food, and environmental fields, emphacizing sample preparation requirements needed in each case.     

Recent advances in capillary electrophoretic migration techniques for pharmaceutical analysis (2013–2015)

This review updates and follows‐up a previous review by highlighting recent advancements regarding capillary electromigration methodologies and applications in pharmaceutical analysis. General approaches such as quality by design as well as sample injection methods and detection sensitivity are discussed. The separation and analysis of drug‐related substances, chiral CE, and chiral CE‐MS in addition to the determination of physicochemical constants are addressed. The advantages of applying affinity capillary electrophoresis in studying receptor–ligand interactions are highlighted. Finally, current aspects related to the analysis of biopharmaceuticals are reviewed. The present review covers the literature between January 2013 and December 2015.