FACTORS THAT INFLUENCE MOBILITY, RESOLUTION AND SELECTIVITY IN CAPILLARY ZONE ELECTROPHORESIS .2. THE ROLE OF THE BUFFERS CATION

The effect of the buffer cation on mobility, resolution and selectivity in capillary zone electrophoresis was investigated. The results show that mobility times of analyte increased with increasing cation size Cs+>Rb+>K+>Na+>Li+. The increase in mobility times was verified by measuring the electroosmotic flows of benzene, mesityl oxide and guanosine in the five alkali buffers. The results show that electroosmotic flows of the three above markers decreased as the cation size increased. The separation of a test mixture of nine dansylated amino acids was better when 0.1 M cesium acetate solution was used rather than lithium acetate. Also, there was no change in the order of elution of the solutes in the test mixture in the five acetate solutions having the same pH and concentration. It was observed that at the same applied voltage (20 kv) the resulting current increased as the atomic weight of the cation increased, which is expected based on charge/size distribution. © 1990, Taylor & Francis Group, LLC. All rights reserved.