The mutual relationships between applied voltage, migration time and peak area in capillary zone electrophoresis

Abstract

This paper investigates the mutual relationships between applied voltage, migration time and peak area in capillary zone electrophoresis (CZE). The theoretical equation describing the relationship between applied voltage and migration time in CZE is T = LL c 1 μ e + gm(eo) V . Based on the equation, in this paper, two equations describing the relationships between S and V, and between S and T are first obtained, and they are S = 1 2 hl L 1 (μ e + μ eo)v , and S = hl 2L o T , respectively. In the three equations, T is migration time; V is applied voltage; S is peak area; L is the total capillary length; L o is the capillary length from inlet of capillary to the center of detector; μ e is electrophoretic mobility; μ eo is electroosmotic mobility; hl is a constant. Experimental results show that there existed good linear relationships between T and 1 V , between S and 1 V , between S and T. For the linear plots of T against 1 V , S against 1 V , and S against T, it was found that all the intercepts of the plots were zero when thermal effect was negligible, but the intercepts of the first two plots were non-zero and only the intercept of the last plot was zero when thermal effect was significant. The reason for the non-zero intercepts is that μ e + μ eo contained in the first two equations significantly increases with the increase of voltage. For the later case, a quantitative equation describing relationship between μ e + μ eo and V is obtained and based on it, the first two equations are corrected. It was found that the experimental results were in a good agreement with the corrected equations. The significance and some potential applications of these relationships are discussed.