CE-MS and related techniques as a valuable tool in tumor biomarkers research

Peptidomics and Capillary Electrophoresis

Peptides play a crucial role in many vitally important functions of living organisms. The goal of peptidomics is the identification of the "peptidome," the whole peptide content of a cell, organ, tissue, body fluid, or organism. In peptidomic or proteomic studies, capillary electrophoresis (CE) is an alternative technique for liquid chromatography. It is a highly efficient and fast separation method requiring extremely low amounts of sample. In peptidomic approaches, CE is commonly combined with mass spectrometric (MS) detection. Most often, CE is coupled with electrospray ionization MS and less frequently with matrix-assisted laser desorption/ionization MS. CE-MS has been employed in numerous studies dealing with determination of peptide biomarkers in different body fluids for various diseases, or in food peptidomic research for the analysis and identification of peptides with special biological activities. In addition to the above topics, sample preparation techniques commonly applied in peptidomics before CE separation and possibilities for peptide identification and quantification by CE-MS or CE-MS/MS methods are discussed in this chapter.

Metabolomic investigation of human diseases biomarkers by CE and LC coupled to MS

Metabolomics is one of the most recent trends in the "omics" era that investigates the end products of an organism activity, that is, all metabolites in a biological system, which are small molecules (less than 1000 Da) from different chemical classes. Metabolomics represents a tool to assess the biochemical activity of a living system through the analysis of substrates and products processed during the metabolism. The analysis of the metabolic profile (nontargeted analysis, i.e. a comparison between samples profiles of individuals) and of specific metabolites (targeted analysis, which quantifies a selected group of metabolites) in biological samples provides an insight into the metabolic state and the biochemical processes of the organism and, therefore, may indicate the onset and the stage of different diseases. An early and accurate diagnosis is essential for successful treatment and probable cure of most illnesses; hence, the investigation of metabolites as disease biomarkers has increased considerably in recent years. This review aims to present the most relevant works that address the nontargeted and targeted analysis of metabolites in different diseases for the past 10 years, including kidney and neurological disorders, cardiovascular diseases, diabetes, and cancer, using CE and LC coupled with the accurate detection of mass spectroscopy.

Capillary electrophoresis based on the nucleic acid detection in the application of cancer diagnosis and therapy

This review focuses on capillary electrophoresis-based nucleic acid detection as it is applied to cancer diagnosis and therapy, and provides an introduction to the drawbacks and future developments of analysis with CE.

Ultrasensitive sample quantitation via selected reaction monitoring using CITP/CZE-ESI-triple quadrupole MS

We demonstrate the direct coupling of transient capillary isotachophoresis/capillary zone electrophoresis (CITP/CZE) with a high-sensitivity triple quadrupole mass spectrometer operating in selected reaction monitoring (SRM) mode for sample quantitation. The capability of CITP/CZE for in situ sample enrichment and separation has been shown to significantly improve the analytical figures of merit. A linear dynamic range spanning 4 orders of magnitude was observed. An average signal-to-noise ratio (S/N) of 49.6 was observed for 50 amol of targeted peptide in the presence of a complex and much more abundant bovine serum albumin (BSA) digest. Correlation of variation (CV) of <10% for peak area was measured from triplicate sample analyses at 50 pM peptide concentration, showing good reproducibility of this online CITP/CZE-SRM mass spectrometry (MS) platform, and with limit of quantitation (LOQ) demonstrated to be well below 50 pM.

Toward total automation of microfluidics for extraterrestial in situ analysis

Despite multiple orbiter and landed missions to extraterrestrial bodies in the solar system, including Mars and Titan, we still know relatively little about the detailed chemical composition and quantity of organics and biomolecules in those bodies. For chemical analysis on astrobiologically relevant targets such as Mars, Europa, Titan, and Enceladus, instrumentation should be extremely sensitive and capable of analyzing a broad range of organic molecules. Microchip capillary electrophoresis (μCE) with laser-induced fluorescence (LIF) detection provides this required sensitivity and targets a wide range of relevant markers but, to date, has lacked the necessary degree of automation for spaceflight applications. Here we describe a fully integrated microfluidic device capable of performing automated end-to-end analyses of amino acids by μCE with LIF detection. The device integrates an array of pneumatically actuated valves and pumps for autonomous fluidic routing with an electrophoretic channel. Operation of the device, including manipulation of liquids for sample pretreatment and electrophoretic analysis, was performed exclusively via computer control. The device was validated by mixing of laboratory standards and labeling of amino acids with Pacific Blue succinimidyl ester followed by electrophoretic analysis. To our knowledge, this is the first demonstration of completely automated end-to-end μCE analyses on a single, fully integrated microfluidic device.

Determination of stimulants and narcotics as well as their in vitro metabolites by online CE-ESI-MS

A simple, rapid and sensitive CE-ESI-MS method for the simultaneous analysis of seven stimulants and narcotics (amphetamine, ephedrine, methadone, pethidine, tetracaine, codeine and heroin) was developed. The CE-ESI-MS experimental conditions were optimized as follows: 20 mmol/L ammonium acetate with pH 9.0 as running buffer, the separation voltage of 22 kV and the sheath liquid of isopropanol/water (1:1 v/v) containing 7.5 mmol/L acetic acid with 3.0 μL/min flow rate. Under the optimized conditions, the stimulants and narcotics were well separated within 4.6 min using a 70-cm length fused-silica capillary (50 μm id). The detection limits (S/N=3) of the CE-ESI-MS analysis were in the range of 0.40-1.0 ng/mL. Method repeatability of intra-day and inter-day was satisfactory. The recoveries obtained from the analysis of spiked urine samples were between 84.1 and 108%. The developed method was successfully applied for the simultaneous analysis of methadone, pethidine and codeine and their in vitro metabolites.

Recent advances in CE-MS: Synergy of wet chemistry and instrumentation innovations

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.