Capillary Electrophoresis

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The complexity and challenges of developing, manufacturing, and controlling cell therapies offer today’s chromatographic scientists new opportunities to join the journey of discovery and innovation needed to develop and commercialize this new drug modality. This article explores the latest developments and highlights the importance of new capillary electrophoresis–mass spectrometry (CE–MS)-based approaches to understand the efficiency of cell therapy production.

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Analytical separation techniques based on the differential migration velocities of analytes under the action of an electric field are gaining increasing acceptance for the analysis of phenolic compounds in edible and medicinal plants and in plant-derived food products. In Part 2 of this review article the authors discuss the fundamental principles and practical aspects of electromigration techniques, including capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC), and capillary electrochromatography (CEC). The development of two-dimensional systems, performed by coupling either liquid chromatography (LC) with an electromigration technique or two electromigration techniques, operated under different separation mechanisms, is also discussed.

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The analytical toolbox used in present-day metabolomics encounters difficulties for the analysis of limited amounts of biological samples. Therefore, a significant number of crucial biomedical and clinical questions cannot be addressed by the current metabolomics approach. Capillary electrophoresis–mass spectrometry (CE–MS) has shown considerable potential for the profiling of polar and charged metabolites in volume-restricted or mass-limited biological samples. This article considers advances that significantly improved the performance of CE–MS for in-depth metabolic profiling of limited sample amounts. Attention is also devoted to various technical aspects that still need to be addressed to make CE–MS a viable approach for volume-restricted metabolomics.

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Inspired by the work of Jorgenson and Lukacs, 30 years ago, the group of Richard Smith at Pacific Northwest National Laboratory in Washington (USA) reported the first online coupling of the microscale separation technique capillary electrophoresis (CE) to electrospray ionization (ESI) mass spectrometry (MS) using a sheath-liquid interface.

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In the biomedical research of molecular bases of both normal and pathological biological processes, it is currently necessary not only to detect, identify, and quantify individual compounds, but also to study their interactions with endo- and exogenous compounds. Obviously, for these purposes it is crucial to develop new advanced high‑performance analytical methods providing high sensitivity, high selectivity, and high throughput. These challenging requirements are well met by capillary electromigration (CE) methods. They have developed in the last three and half decades into high‑performance separation techniques suitable for the analysis of a wide spectrum of both low- and high‑molecular mass bioactive compounds.

In this article, we discuss the use of CE-MS (sheath flow interface) for analysis of intact proteins as well as of protein digests. We discuss the unique aspects that the user needs to be aware of while testing biotherapeutics versus small molecule drugs. We also highlight that the optimization of CE and MS parameters together result in the creation of a more robust and reproducible protein analysis approach. Finally, we list some of the most common errors that are likely to occur during CE-MS analysis and suggest ways to overcome them.

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A chiral ionic liquid, namely 1-ethyl-3-methyl imidazole L-tartrate ([EMIM][L-Tar]), was applied as a new chiral ligand for the enantioseparation of tryptophan, tyrosine, and phenylalanine enantiomers by chiral ligand exchange CE. To validate the unique behavior of [EMIM][L-Tar], the performance of L-tartaric acid and 1-ethyl-3-methyl imidazole L-proline as chiral ligands was investigated to make a comparison with [EMIM][L-Tar]. Then the separation mechanism was further discussed. It was proven that [EMIM][L-Tar] was a good chiral ligand and would have good application prospects in separation science.

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An analytical methodology for the characterization of the primary structure of biotherapeutic proteins using sheathless CE–ESI-MS-MS instrumentation is presented. For the first time, complete sequence coverage can be achieved using a bottom-up proteomic approach from a single analysis of a tryptic digest. In a biosimilarity assessment, a single amino acid substitution was detected.

October 2006. The authors demonstrate the use of multiple-injection affinity capillary electrophoresis (MIACE) and several variations to MIACE to determine binding constants between the glycopeptide antibotics vancomycin, ristocetin, and teicoplanin from Streptomyces orientalis, Nocardia lurida, and Actinoplanes teichomyceticus, respectively, and D-Ala-D-Ala terminus peptides.

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Potentiometry is a new detection method for liquid chromatography (LC) and capillary electrophoresis (CE). The principle behind this method is familiar to chromatographers because the signals depend on the partitioning tendency of analytes over the sensor coating and the eluent. This partitioning provokes a change in the surface potential and the detection of these changes can be classified as "potentiometric". A conversion algorithm is needed to convert the generated signals to concentration-related tracings (chromatograms).

Capillary extraction (CEx) is used to study the solventless in-tube extraction of naphthalene, acenaphthene, phenanthrene, fluoranthene, chrysene, benzo(a)pyrene and coronene in aqueous samples prepared by analyte spiking into clean waters or, as an alternative, by using the generator–column method of sample preparation. Analysis of laden extractors is conveniently performed by high-resolution gas chromatography (GC), with a flame-ionization detector (FID). Extraction set-ups and main extraction variables are investigated from a practical point of view. For 2- to 4-ring polycyclic aromatic hydrocarbons (PAHs), equilibrium times are within a few minutes, analytical sensitivity is in the parts-per-billion (ppb) range and reproducibility is better than 10% relative standard deviation (RSD) (n = 6). Coronene behaviour is unique and presumably determined by extreme hydrophobicity and thus very negligible aqueous solubility: in-tube extraction of coronene seems possible only if starting from..