OPTIMIZATION STRATEGIES IN MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY - OPTIMIZATION OF THE TEMPERATURE OF THE SEPARATION CAPILLARY

The influence of the temperature of the capillary on the separation of small molecules by micellar electrokinetic chromatography with buffer s containing sodium dodecyl sulfate was examined. Investigated paramet ers were the electroosmotic velocity, the migration velocity of the mi celles, the strength of the electric current, retention factors and pl ate numbers. Thermodynamic parameters associated with micelle solubili zation were evaluated from the variation of the retention factor with temperature. An investigation was carried out as to whether the depend ence of the electroosmotic velocity and the migration velocity of the micelles are mainly due to the decrease in viscosity and dielectric co nstant with increase in temperature. The temperature of the capillary strongly affects the plate numbers for various solutes obtained with t he same chromatographic system. In order to exclude secondary effects by alteration of the instrumental band broadening and the electroosmot ic velocity with temperature, a method is presented that permits the d evelopment of chromatograms in MEKC at various temperatures with const ant injected plug length and constant electroosmotic velocity. The res ults are discussed from the point of view of minimizing the analysis t ime and optimizing the resolution.