Quantification analysis capillary electrophoresis

Identification and quantification of natural dyes need high performance analytical techniques, appropriate for the analysis of materials of complicated matrices containing a small amount of coloured substances. This requirement perfectly fits coupling of modern separation modules (usually high performance liquid chromatography in reversed phase mode, RPLC, but also capillary electrophoresis, CE) with selective detection units (mainly mass spectrometer). 

Artificial Neural Networks Based on Principal Component Analysis Input Selection for Quantification in Overlapped Capillary Electrophoresis Peaks. 

This area of analytical chemistry includes a great number of instruments that range from colour comparators and other visual comparison devices to automated spectrophotometers that can carry out multicomponent analysis. Liquid chromatography and capillary electrophoresis have accelerated the development of improved UV/Visible detectors, which are at the origin of the current mode of acquiring chromatograms, accompanied by the possibility of identification and quantification of compounds. 

N. A. Guzman, H. Ali, J. Moschera, K. Iqbal, and A. W. Malick, Assessment of capillary electrophoresis in pharmaceutical applications — analysis and quantification of a recombinant cytokine in an injectable dosage form, J. Chromatogr., 559 307 (1991). 

The same authors also applied capillary electrophoresis to the study of benazepril hydrochloride and several angiotensin-converting enzyme inhibitors [43]. Separation of the compounds was performed by means of two phosphate buffers (each 0.1 M) at pH 7 and 6.25, respectively [42], Due to the highest selectivity of the first mentioned running buffer, the same system has been applied for the quantification of benazepril and other compounds in their corresponding pharmaceutical formulations. It was found that the possibility of simultaneous identification and quantification of the active ingredient in the finished products was especially attractive, and that excipients do not adversely affect the results. This article deals with the validation of some parameters of the quantitative analysis, namely linearity, precision, accuracy, and robustness [43],... 

In past years, on line chromatographic coupling techniques such as HPLC and CE coupled to ICP-MS with the isotope dilution technique have been used for element quantification in speciation analysis. An interesting application of the isotope dilution technique in medical research was proposed recently by Prange and co-workers, who added highly enriched " S, Cu, Zn and Cd spikes to the interface of the CE-ICP-MS system. The authors separated isoforms of metallothionein (e.g., of rabbit liver) by capillary electrophoresis and quantified S, Cd, Cu and Zn concentrations in isoforms by ICP-SFMS using the isotope dilution technique. A new selenized yeast reference material (SELM-1) for methionine, selenomethionine (SeMet) and total selenium content has also certified by an intercomparison exercise. ... 

In recent years there has been a growing interest in the use of electrospray ionization-mass spectrometry (ESI-MS) either as a stand-alone technique, or following an analytical separation step like CE, to study and measure a wide variety of compounds in complex samples such us foods (Simo et al. 2005). ESI provides an effective means for ionising from large (e.g., proteins, peptides, carbohydrates) to small (e.g., amino acids, amines) analytes directly from solution prior to their MS analysis without a previous derivatization step. Santos et al. (2004) proposed the use of CE-ESI-MS for the separation and quantification of nine biogenic amines in white and red wines. More recently, the possibilities of two different CE-MS set-ups, namely, capillary electrophoresis-electrospray-ion trap mass spectrometry (CE-IT-MS) and capillary electrophoresis-electrospray-time of flight mass spectrometry (CE-TOE-MS) to analyze directly biogenic amines in wine samples without any previous treatment has been studied (Simo et al. 2008). 

Molina, E., Martfn-Alvarez R J., Ramos M. (1999). Analysis of cows , ewes and goats milk mixtures by capillary electrophoresis Quantification by multivariate regression analysis. Int. 

A selective CZE microassay was developed for the determination of dexa-methasone phosphate and its major metabolite, dexamethasone, in tears (325). An internal standard, indoprofen, was used for quantitation. The limits of detection and quantification were 0.5 and 2.0 pg/mL, respectively. The quantitative method was essential for the in-vivo determination of the dexamethasone concentration-time profiles in tears after the application of the anti-inflammatory drug. Two examples of rapid and simple drug analysis in pharmaceutical formulations using capillary electrophoresis can be found in the methods described for the separation of naphazoline, dexamethasone, and benzalkonium in nose drops (326). 

Figure 1 Electropherograms of the casein fraction of a mixture of one-third each of bovine, ovine, and caprine miik. Peak identification 1, bovine asi-casein 2, ovine asi-casein 3, bovine K-casein 4, ovine K-casein 5, bovine jS-casein Ak 6, caprine k-casein 7, bovine S-casein A 8, ovine 2-casein and caprine p2-casein 9, ovine j8i-casein and caprine, -casein. Conditions hydrophilic coated fused-silica capillary 50 pm i.d. x 57 cm separation buffer, 6 mol I" urea, 0.32 mol I citric acid, 20 mmol I sodium citrate, pH 3.0, containing 0.5gr methylhydroxyethyl-cellulose applied voltage, 25 kV injection, 15 s temperature, 45°C. (Reprinted with permission from Molina E, Martin-Alvarez PJ, and Ramos M (1999) Analysis of cows , ewes and goats milk mixtures by capillary electrophoresis Quantification by multivariate regression analysis. International Dairy Journal 9 99-105 Elsevier.)...

Chromatographic methods are routinely applied to the detection and quantification of toxins. Gas-phase chromatography (GPC) is not well adapted to nonvolatile microcystins and requires chemical derivation steps for other toxins however, its ability to be directly coupled to mass spectrometers makes it a powerful tool. Capillary electrophoresis coupled to mass spectrometry has also been applied to the analysis of microcystins and saxitoxins. Although it seems to present several advantages over other techniques, it remains at a developmental stage as far as toxins are concerned. 

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