Pharmaceutical and biomedical applications of capillary electrophoresis/electrochemistry

Abstract

The use of capillary electrophoresis/electrochemistry (CEEC) for the analysis of microdialysis samples obtained for pharmacokinetic and neurochemical studies is described, as well as the development of new types of electrodes and waveforms which increase the selectivity of this technique for specific classes of analytes. CEEC with a carbon fiber electrode was employed for the analysis of microdialysis samples. Microdialysis is an in vivo sampling technique that yields very small samples for analysis (less than 1 microL). Therefore, capillary electrophoresis, with its small volume requirements, is an excellent choice for the analytical method. CEEC was used to study the pharmacokinetics of L-dopa and the release of aspartate and glutamate following a high K+ infusion in the brain. Several modified electrodes which increase the applicability of CEEC in pharmaceutical and biomedical analysis are described. One of these is a gold/mercury electrode which is highly selective for thiols and was used for the determination of glutathione in a rat brain. An alternative method for the detection of thiols employed a chemically modified electrode containing cobalt phthalocyanine. In this case, an electrocatalyst reduces the overpotential of thiols at the carbon electrode and makes it possible to detect them at a much lower and more selective oxidation potential. This electrode was used for the detection of cysteine in urine. The development of pulsed amperometric detection for capillary electrophoresis is also described and is demonstrated by the detection of glucose in blood. Lastly, a method for the detection of peptides based on the formation of a copper complex and detection at a carbon fiber electrode is discussed.

The Role of and the Place of Method Validation in Drug Analysis Using Electroanalytical Techniques

“…After the standard addition, the results of these two sets samples should be plotted as a function of analyte addition concentration in the same graph. The slopes of these curves are compared and if the slopes of these two linear regression curves are the same, the matrix does not effect on the analysis result [1][2][3][4][5][6][7][8][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40].…”

“…A linearity study for electroanalytical techniques like other analytical methods verifies that the response is linearity proportional to the analyte concentration in the concentration range of sample solutions. When a specific characteristic defined to the electroanalytical signal without any doubt than a relationship between the concentration and response can be investigated [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Linearity of an electroanalytical method is a measure of how well calibration plot of electroanalytical response versus concentration approximates a straight line.…”

“…All electroanalytical procedures require some type of validation, regardless of whether the method is used for stability, purity, identification, potency, in-process analysis, release or acceptance testing, etc like other analytical methods. Although, currently there are differences in the technical requirements among various regulatory agencies, a guideline entitled "Validation of Analytical Procedures" prepared by the International Conference on Harmonization of Technical Requirements for Registration Pharmaceuticals for Human use (ICH) outlines the parameters that should be considered during the validation exercise [1][2][3][4][5][6][7][8][9][10][11][12].…”

Principles, Concepts and Strategies of Stereoselective Synthesis

“…[100][101][102] Using chiral selectors as the running buffer additives or immobilized ligands, capillary electrophoresis has found a wide range of applications. CE is applied as an efficient and versatile approach for the physicochemical characterization of natural bioactive molecules, 103,104 and chiral resolution of charged substances such as biomolecules 105,106 and low-molecularweight basic or acidic drugs. 107 Capillary electrophoresis is a powerful technique in pharmaceutical analysis, 108,109 useful in the determination of chiral purity in pharmaceuticals, and routine quality control of marketed pharmaceuticals.…”

Bioanalytical profile of the l-arginine/nitric oxide pathway and its evaluation by capillary electrophoresis

“…Microchipintegrated CEECD has been developed and tested with biomedical samples, showing excellent analytical performance and good technological potential for microfabrication [335]. The effort to develop CEECD applications focuses on the analysis of neurochemically and metabolically important small biogenic and essential molecules, including amino acids [336][337][338][339][340][341][342], monoamines [343][344][345][346][347][348][349][350][351][352], excitatory and inhibitory neurotransmitters with low electrochemical activity [342,353], and some vitamins and cofactors such as ascorbic acid and glutathione [354][355][356][357][358][359][360][361][362][363][364].…”