No abstract

This work verifies the potential of CE in the analysis of significant impurities of montelukast sodium - an active ingredient for the treatment of bronchial asthma. Using 20 mM borate buffer pH 9.2 with 10 mM SDS and 10 mM (2-hydroxypropyl)-gamma-CD (2HP-gamma-CD) it was possible to separate montelukast and several impurities, including its cis-isomer, after exposure to light and oxygen. The obtained method surpasses a chromatographic method for montelukast sodium in terms of time of analysis (9 min of CE analysis vs. 35 min HPLC) and efficiency (CE offered over 900 000 theoretical plates for montelukast). Good repeatability of the method was supported by the low % RSD for the migration time of montelukast (0.53%). For the first time, the capillary electrophoretic method was employed for temporal study of the degradation of montelukast. The results showed that degradation of montelukast and the formation of the cis-isomer mainly occurred during the first 2 days of exposure, and occurred to a higher degree when there was no contact with the air (oxygen) in the exposed sample.

The use of glass and PDMS microchips has been investigated to perform rapid and efficient separation of allergenic whey proteins by IEF. To decrease EOF and to limit protein adsorption, two coating procedures have been compared. The first one consists in immobilizing hydroxypropyl cellulose (HPC) and the second one poly(dimethylacrylamide-co-allyl glycidyl ether) (PDMA-AGE). EOF limitation has been evaluated using frontal electrophoresis of a fluorescent marker of known effective mobility. EOF velocity was decreased by a factor about 100 and 30, respectively. pH gradient formation has been evaluated for each microchip using fluorescent pI markers. It was demonstrated that as expected a coating was essential to avoid pH gradient drift. Both coatings were efficient on glass microchips, but only PDMA-AGE allowed satisfying focusing of pI markers on PDMS microchips. Fluorescent covalent and noncovalent labelings of milk proteins have been compared by IEF on slab-gels. IEF separation of three major allergenic whey proteins [beta-lactoglobulin A (pI 5.25) and B (pI 5.35) and alpha-lactalbumin (pI 4.2-4.5)] was performed in both microchips. Milk proteins were separated with better resolution and shorter analysis time than by classical CIEF. Finally, better resolutions for milk allergens separation were obtained on glass microchips.

For the first time the versatility of CE is demonstrated for the separation of different types of anticancer drugs - anthracyclines and taxanes simultaneously. The use of these drugs in combination therapy for cancer has sparked interest in the development of methods for potential application. The simultaneous analysis of anthracyclines and taxanes can significantly increase a sample throughput of a clinical laboratory. The study shows the potential of CE for such a challenge: anthracyclines and taxanes were separated by CZE, MEKC and MEEKC. The MEEKC method was successfully applied to these compounds for the first time and was characterised by very short separation time, high efficiencies of peaks and was proven to be generic for the separation of different combinations of anthracyclines and taxanes. This separation approach could be highly beneficial for clinical analysis if applied with a sensitive detection system. MEKC and high-speed MEEKC methods were proven to show good potential in their application to plasma samples.