Factors that Influence Mobility, Resolution, and Selectivity in Capillary Zone Electrophoresis. I. Sodium Phosphate vs. Potassium Phosphate

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Abstract
The effect of buffer type on mobility, selectivity and resolution in capillary zone electrophoresis (CZE) was studied. The results show that the sodium phosphate buffer gave shorter mobility times (tM) for a test dansyl amino acid mixture than the potassium phosphate buffer having the same concentration and pH. The resolution and selectivity were also better using the sodium phosphate buffer. A comparison of resolution, tM and selectivity using a monohydrogen and a dihydrogen sodium phosphate buffer (0. 1 M, pH 7. 0) showed no appreciable differences in selectivity and resolution, but the dihydrogen phosphate buffer gave tM which are almost 45% shorter than those obtained with the monohydrogen phosphate buffer. When monohydrogen and dihydrogen potassium phosphate (0. 1 M, pH 7) were used, differences in tM, selectivity and resolution were observed. Resolution improved with an increase in the buffer concentration (0. 2 M vs. 0. 1 M) but worsened and tM got considerably shorter when the concentration of the buffer was decreased from 0. 1 M to 0. 05 M.