Capillary Electrochromatography A Versatile Tool for Biochemical Analysis (original) (raw)

Capillary electrochromatography: An alternative to HPLC and CE

Journal of Separation Science, 2002

CEC is a technique that has attracted increased interest in recent years. It combines the advantages of high efficiency of electrophoretic separation methods with the greater selectivity characteristic of HPLC. In this paper we explore the use of CEC as a potential alternative to conventional HPLC, l-HPLC, and CE. Recent developments, both theoretical and experimental, are reviewed. The practical aspects of application of CEC in various modes of separation are also discussed.

Capillary Electrochromatography: A Powerful Tool for the Resolution of Complex Mixtures

Journal of AOAC INTERNATIONAL

Methods such as capillary electrophoresis (CE) and capillary liquid chromatography (LC) are particularly useful in the analysis of complex mixtures because of their high resolving power. Continued refinement of these techniques has led to a novel separation method known as capillary electrochromatography (CEC), also referred to as capillary electrokinetic chromatography, which is a combination of capillary LC and conventional CE. As in LC, mobile phase is transported through a column where partitioning of solutes occurs. In CEC, mobile phase flow is generated by electroosmosis, which arises when an electric potential is applied across the long axis of the capillary column. The favorable flow dynamics of electroosmosis result in higher chromatographic efficiencies in CEC relative to LC. If the species of interest are charged, a second separation mechanism is afforded by electrophoresis. CEC combines the high efficiency of capillary electrophoretic separations with the broad range of ...

Column technology in capillary electrophoresis and capillary electrochromatography

Electrophoresis, 1997

Column technology in capillary electrophoresis and capillary electrochromatography A review of column technology in capillary electrophoresis (CE) including wall modification processes and open tubular as well as packed column formats in capillary electrochromatography (CEC) are presented. There are many approaches which can be used to solve separation problems which provide higher efficiency andlor shorter analysis times in comparison to other chromatographic techniques. However, both CE and CEC are still relatively undeveloped in comparison to a more mature method such as high performance liquid chromatography (HPLC) and improvement in column technology is changing rapidly.

Capillary electrochromatography: A review

Journal of Microcolumn Separations, 1997

. Abstract: Capillary electrochromatography CEC is a modern liquid chromatographic technique which has attracted renewed curiosity from the scientific community in recent years, despite having origins in the 1970s. The growing interest in this field is reflected in the increasing number of scientific publications and presentations dealing with the technique; the majority of work reviewed here is from the last five years. This review concerns itself primarily with both the development of capillary electrochromatography, from early experimentation to the present day, and its widespread application. The fundamental theory is dis-Ž cussed, as well as experimental aspects such as mode of operation isocratic or . gradient and detection. Considerable attention is devoted to CEC columns; in particular, the preparation of frits and their associated problems. A large number of applications are summarised in tabular form, which provides an insight into the capabilities and scope of this technique.

AN OVERVIEW OF CAPILLARY ELECTROPHORESIS

O. Krupa Santhi*, T. Sandhya Rani, Md. Shakirunisa, V. Supriya, Ch. Anupama Swathi, Dr. K. Padmalatha

Capillary electrophoresis is an effective separation technique where the ions are separated based on their electrophoretic mobility under an applied voltage. Capillary electrophoresis is most predominately used because it gives faster results and provides a high-resolution separation. It is one of the useful techniques as there is a large range of detection methods available. CE is an alternative for traditional methods such as gel electrophoresis and liquid chromatography and is employed to detect both high and low affinity molecular interactions, and separation of both charged and non-charged molecules. CE classified according to mode of separation on the basis of differences in charge, size and frictional force, offers fast separations with excellent efficiency. CE is an effective analytical tool for assay of pharmaceutical API including determination of drug related impurities. It possess other versatile applications like chiral, and bioanalysis of pharmaceutical API This review focuses on various aspects of capillary electrophoresis and CE-based separation modes with some advantages and disadvantages along with applications. KEYWORDS: Capillary Electrophoresis, High Resolution, Frictional Force, liquid chromatography

Recent applications in capillary electrochromatography

Electrophoresis, 2001

The most recent and important applications in capillary electrochromatography (CEC) are summarized, covering literature published since May 2001. A selection of new developments in stationary phases for CEC is highlighted, and enantiomeric separations and chiral stationary phases are discussed. Also, CEC applications of biological molecules, pharmaceuticals, and applications in the field of industrial and environmental analysis are summarized. For this review three modes of CEC were taken into account, i.e., packed-column CEC, CEC using monolith technology, and open-tubular CEC.

Semipreparative Capillary Electrochromatography

Analytical Chemistry, 2001

Capillaries with inner diameters of 550 µm have successfully been packed with 1.5-µm octadecyl silica particles using frits made of macroporous polymers by the UV photopolymerization of a solution of glycidyl methacrylate and trimethylolpropane trimethacrylate. This type of frit is found superior to one made of low-melting point poly-(styrene-co-divinylbenzene) beads. Bubble formation is not observed to occur within these capillary columns under our experimental conditions. Separations can be achieved with sample injection volumes as high as 1 µL. To demonstrate its semipreparative use, a mixture of 500 nL of taxol (20 mM) and its precursor, baccatin III (30 mM), is separated using such a column with a Tris buffer. Capillary electrochromatography (CEC) is a powerful separation technique that combines high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE). It has attracted much interest in the past few years because it has (1) high separation efficiency, (2) high selectivity, (3) low solvent consumption, and (4) low operational costs. Recently, several research groups have presented many impressive applications of CEC. A broad variety of different species, such as corticosteroids, 1 amino acids, 2-4 proteins and peptides, 5-8 carbohydrates, 9 environmental contaminants, 10,11 natural products, 12,13 and pharmaceuticals, 14-16 have successfully been separated using CEC. Several

Analytical Separations Using Molecular Micelles in Open-Tubular Capillary Electrochromatography

Analytical Chemistry, 2002

Open-tubular capillary electrochromatography (OT-CEC) is an alternative approach to conventional CEC. The primary advantage of OT-CEC is the elimination of problems associated with frits and silica particles in conventional CEC. This report is an investigation of the utility of using a polymeric surfactant (molecular micelle) for OT-CEC. In this approach, fused-silica capillaries coated with thin films of physically adsorbed charged polymers are developed by use of a polyelectrolyte multilayer (PEM) coating procedure. The PEM coating is constructed in situ by alternating rinses with positively and negatively charged polymers, where the negatively charged polymer is a molecular micelle. This can offer a number of advantages for separation of hydrophobic analytes. In this study, poly-(diallyldimethylammonium chloride) was used as the cationic polymer and poly(sodium N-undecanoyl-L-glycinate) was used as the anionic polymer for PEM coating. The performance of the modified capillaries as a separation medium is evaluated by use of seven benzodiazepines as analytes. The run-to-run, day-today , week-to-week, and capillary-to-capillary reproducibilities of electroosmotic flow are very good with relative standard deviation values of less than 1% in all cases. In addition, the chromatographic performance of the monomeric form of the molecular micelle is compared for the separation of these analytes. The PEM-coated capillary was remarkably robust with more than 200 runs accomplished in this study. Strong stability against extreme pH values was also observed. The general utility of this approach is discussed in detail. Capillary electrochromatography (CEC) is a hybrid electroseparation technique that couples the selectivity of highperformance liquid chromatography (HPLC) and the separation efficiency of capillary electrophoresis (CE). 1-5 Such studies have demonstrated that CEC provides high resolution, short analysis time, smaller sample and buffer consumption, and efficiencies

Analytical separations in open-tubular capillary electrochromatography

ELECTROPHORESIS, 2003

This review represents a summary of recent progress in open-tubular capillary electrochromatography (OT-CEC) for chiral and achiral separations. The OT-CEC approach is an alternative to packed-CEC that could eliminate the problems associated with retaining frits and silica particles. In OT-CEC, the stationary phase is immobilized on the inner walls of the capillary. Preparation of the stationary phase is critical for OT-CEC. The preparation methods for capillary columns include (i) adsorption, (ii) covalent bonding and/or cross-linking, (iii) porous layers, (iv) chemical bonding after etching, (v) sol-gel, and (vi) molecular imprinting. Major developments, potential applications, technical difficulties and advantages associated with these wall coatings in OT-CEC are presented. In addition, the coupling of OT-CEC with mass spectrometry (MS) is briefly reviewed. Several applications of this hyphenated technique for analytical separations are also summarized.