After shining as the ultimate separation - sequencing technique used for the successful completion of the Human Genome Project, in the early 2000s CE experienced lowered popularity among separation scientists. The renewed interest in recent years relates to the separation needs, especially in proteomics, metabolomics, and glycomics, where CE complements liquid chromatography techniques. This interest is further boosted by the regulators requiring additional separation techniques for characterization of newly developed pharmaceuticals. This paper gives a short overview of recent developments in the on-line interfacing of CE separation techniques with electrospray ionization/mass spectrometric analysis. Both the instrumentation and selected CE/ESI/MS applications including analyses of peptides, proteins, and glycans are discussed with the stress on research published in the past 3 years. Techniques related to the proteomic and glycomic analyses such as sample preconcentration, on-line protein digestion, and analyte derivatization prior CE/ESI/MS analysis are also included.
- MeSH
- Electrophoresis, Capillary methods MeSH
- Spectrometry, Mass, Electrospray Ionization methods MeSH
- Humans MeSH
- Peptides analysis chemistry MeSH
- Polysaccharides analysis chemistry MeSH
- Proteins analysis chemistry MeSH
- Proteomics methods MeSH
- Systems Integration MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
Capillary electrophoresis hyphenated with electrospray mass spectrometry (CE-ESI-MS) has emerged in the past decade as one of the most powerful bioanalytical techniques. As the sensitivity and efficiency of new CE-ESI-MS interface designs are continuously improving, numerical modeling can play important role during their development. In this review, different aspects of computer modeling and simulation of CE-ESI-MS interfaces are comprehensively discussed. Relevant essentials of hydrodynamics as well as state-of-the-art modeling techniques are critically evaluated. Sheath liquid-, sheathless-, and liquid-junction interfaces are reviewed from the viewpoint of multidisciplinary numerical modeling along with details of single and multiphase models together with electric field mediated flows, electrohydrodynamics, and free fluid-surface methods. Practical examples are given to help non-specialists to understand the basic principles and applications. Finally, alternative approaches like air amplifiers are also included. © 2014 Wiley Periodicals, Inc. Mass Spec Rev 34: 558-569, 2015.
- MeSH
- Algorithms MeSH
- Models, Chemical MeSH
- Electrophoresis, Capillary instrumentation methods MeSH
- Electromagnetic Fields MeSH
- Spectrometry, Mass, Electrospray Ionization instrumentation methods MeSH
- Hydrodynamics MeSH
- Humans MeSH
- Computer Simulation MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
One of the challenging instrumental aspects in coupling an automated CE instrument with ESI mass spectrometry (CE-MS) is finding the balance between the stability, reproducibility and sensitivity of the analysis and compatibility with the standard CE instrumentation. Here, we present a development of a new liquid junction based electrospray interface for automated CE-MS, with a focus on the technical design followed by computer modeling of transport conditions as well as characterization of basic performance of the interface. This hybrid arrangement designed as a microfabricated unit attachable to the automated CE instrument allows using of a wide range of separation capillaries with respect to their diameter, length or internal coating (e.g., for suppressed electroosmotic flow). Different compositions of the ESI liquid and background electrolyte solutions can be used if needed. The microfabricated part, prepared by laser machining from polyimide, includes a self-aligning liquid junction, a short transport channel, and a pointed sprayer for the electrospray ionization. This microfabricated part is positioned in a plastic connection block securing the separation capillary and flushing ports. Transport conditions were modelled using computer simulation and the real life performance of the interface was compared to that of a commercial sheath liquid interface. The basic performance of the interface was demonstrated by separations of peptides, proteins, and oligosaccharides.
- MeSH
- Models, Chemical MeSH
- Electrophoresis, Capillary instrumentation MeSH
- Mass Spectrometry instrumentation MeSH
- Automation, Laboratory MeSH
- Microfluidic Analytical Techniques instrumentation methods MeSH
- Proteins analysis isolation & purification MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
This overview deals with the latest development of electrophoresis in capillaries and microfluidic devices coupled to MS detection. A wide selection of relevant articles covers the literature published from January 2010 till June 2012 as a continuation of the review article on the same topic by Pantuckova et al. [Electrophoresis 2011, 32, 43-51]. Special attention is paid to the new improvements in instrumentation and methodology of three interfacing methods, ESI, matrix-assisted desorption/ionization, and ICP. Representative examples illustrate applications in the proteomics, glycomics, metabolomics, biomarker research, forensics, pharmacology, food analysis and single-cell analysis. The combinations of MS with capillary versions of electrochromatography, ITP, IEF, and micellar electrokinetic chromatography are not included.
- MeSH
- Single-Cell Analysis methods MeSH
- Food Analysis methods MeSH
- Biomarkers analysis MeSH
- Electrophoresis, Capillary methods trends MeSH
- Spectrometry, Mass, Electrospray Ionization methods MeSH
- Mass Spectrometry methods MeSH
- Drug Contamination MeSH
- Microfluidic Analytical Techniques instrumentation MeSH
- Proteomics methods MeSH
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization methods MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
A new method for the simultaneous separation of cocaine and four metabolites in urine by CE-ESI-MS via a pressurized nanoliquid junction interface was developed. The resolution of cocaine, cocaethylene, benzoylecgonine, norcocaine, and ecgonine methyl ester was achieved in a polyvinyl-alcohol-coated capillary with 75 μm id × 50 cm total length, using a 15 mM ammonium formate electrolyte solution (pH 9.5) in less than 15 min. In addition, to enhance sensitivity, a field-amplified sample injection (FASI) was evaluated in terms of injection time and sample solvent composition. The limits of detection achieved with the FASI method ranged from 1.5 to 10 ng/mL for all the compounds. The detection of the studied compounds was performed using an ion-trap mass spectrometer in a positive ionization mode. A mixture of methanol:water (80:20 v/v) containing 0.1% v/v of formic acid was employed as spray liquid and delivered at ~200 nL/min. Under optimal CE-MS conditions, linearity was assessed in the concentration range of interest for all analytes with correlation coefficients r² ≥ 0.9913. Intra- and inter-day precision provided a relative standard deviation lower than 1.54% for migration times and lower than 12.15% for peak areas. Finally, urine samples, spiked with the standard mixture, were extracted using a solid-phase extraction procedure and injected under FASI conditions, providing recoveries from 80% to 94% for all analytes.
- MeSH
- Electrophoresis, Capillary instrumentation methods MeSH
- Spectrometry, Mass, Electrospray Ionization instrumentation methods MeSH
- Cocaine metabolism urine MeSH
- Hydrogen-Ion Concentration MeSH
- Humans MeSH
- Nanotechnology instrumentation methods MeSH
- Reproducibility of Results MeSH
- Sensitivity and Specificity MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
This review focuses on the latest development of microseparation electromigration methods in capillaries and microfluidic devices coupled with MS for detection and identification of important analytes. It is a continuation of the review article on the same topic by Kleparnik (Electrophoresis 2015, 36, 159-178). A wide selection of 161 relevant articles covers the literature published from June 2014 till May 2016. New improvements in the instrumentation and methodology of MS interfaced with capillary or microfluidic versions of zone electrophoresis, isotachophoresis, and isoelectric focusing are described in detail. The most frequently implemented MS ionization methods include electrospray ionization, matrix-assisted desorption/ionization and inductively coupled plasma ionization. Although the main attention is paid to the development of instrumentation and methodology, representative examples illustrate also applications in the proteomics, glycomics, metabolomics, biomarker research, forensics, pharmacology, food analysis, and single-cell analysis. The combinations of MS with capillary versions of electrochromatography, and micellar electrokinetic chromatography are not included.
- MeSH
- Single-Cell Analysis methods MeSH
- Food Analysis methods MeSH
- Biomarkers analysis MeSH
- Cell Line MeSH
- Chromatography methods MeSH
- Electrophoresis, Capillary instrumentation methods MeSH
- Glycomics MeSH
- Spectrometry, Mass, Electrospray Ionization instrumentation methods MeSH
- Mass Spectrometry methods MeSH
- Isoelectric Focusing instrumentation methods MeSH
- Lab-On-A-Chip Devices * MeSH
- Humans MeSH
- Metabolomics methods MeSH
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization instrumentation methods MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
Affinity capillary electrophoresis (ACE) is typically used for the determination of stability constant, Kst, of weak to moderately strong complexes. Sensitive detection such as mass spectrometry (MS) is required for extension of ACE methodology for estimation of Kst of stronger complexes. Consequently, an efficient interface for hyphenation of CE with MS detection is necessary. For evaluation of interfaces for electrospray ionization mass spectrometric (ESI/MS) detection in ACE conditions, potassium-crown ether complexation was used as model system. The effective mobilities of the crown ether ligands and the Kst of their potassium complexes were measured/determined by ACE-ESI/MS using two lab-made interfaces: (i) a sheathless porous tip CE-ESI/MS interface and (ii) a nano-sheath liquid flow CE-ESI/MS interface, and, in turn, compared with those obtained by ACE with UV spectrophotometric detection. Apparent stability constant of potassium-crown ether complexes in 60/40 (v/v) methanol/water mixed solvent, pH* 5.5, was about 1300 L/mol for dibenzo-18-crown-6, 1600 L/mol for benzo-18-crown-6 and 5200 L/mol for 18-crown-6 ligands, respectively. It was observed that electrophoretic mobilities from CE-MS experiments differ from reference values determined by UV detection by ∼7% depending on the CE-MS interface used. Good agreement of CE-MS and CE-UV data was achieved for nano-sheath liquid flow interface, in which the spray potential and the CE separation potential can be effectively decoupled. As for sheathless porous tip interface, a correction procedure involving a mobility marker has been proposed. It provides typically only ca. 1% difference of effective mobilities and Kst values obtained from CE-MS data as compared to those received by the reference ACE-UV method.
This review focuses on the latest development of microseparation electromigration methods in capillaries and microfluidic devices with MS detection and identification. A wide selection of 183 relevant articles covers the literature published from June 2012 till May 2014 as a continuation of the review article on the same topic by Kleparnik [Electrophoresis 2013, 34, 70-86]. Special attention is paid to the new improvements in the theory of instrumentation and methodology of MS interfacing with capillary versions of zone electrophoresis, ITP, and IEF. Ionization methods in MS include ESI, MALDI, and ICP. Although the main attention is paid to the development of instrumentation and methodology, representative examples illustrate also applications in the proteomics, glycomics, metabolomics, biomarker research, forensics, pharmacology, food analysis, and single-cell analysis. The combinations of MS with capillary versions of electrochromatography and micellar electrokinetic chromatography are not included.
- MeSH
- Single-Cell Analysis instrumentation methods MeSH
- Food Analysis instrumentation methods MeSH
- Equipment Design MeSH
- Electrophoresis, Capillary instrumentation methods MeSH
- Mass Spectrometry instrumentation methods MeSH
- Humans MeSH
- Metabolomics instrumentation methods MeSH
- Microfluidic Analytical Techniques instrumentation methods MeSH
- Polysaccharides analysis MeSH
- Proteins analysis MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
CE with MS detection is a hyphenated technique which greatly improves the ability of CE to deal with real samples, especially with those coming from biology and medicine, where the target analytes are present as trace amounts in very complex matrices. CE-MS is now almost a routine technique performed on commercially available instruments. It faces currently a tremendous development of the technique itself as well as of its wide application area. Great interest in CE-MS is reflected in the scientific literature by many original research articles and also by numerous reviews. The review presented here has a general scope and belongs to a series of regularly published reviews on the topic. It covers the literature from the last 2 years, since January 2008 till June 2010. It brings a critical selection of related literature sorted into groups reflecting the main topics of actual scientific interest: (i) innovations in CE-ESI-MS, (ii) use of alternative interfaces, and (iii) ways to enhance sensitivity. Special attention is paid to novel electrolyte systems amenable to CE-MS including nonvolatile BGEs, to advanced CE separation principles such as MEKC, MEEKC, chiral CE, and to the use of preconcentration techniques.
