Multivariate analysis of capillary electrophoresis separation conditions for Z-E isomers of clomiphene.

Plackett-Burman (P-B) experimental design has been used to optimize the factors affecting separation of Z and E isomers of clomiphene (zuclomiphene and enclomiphene respectively) using capillary electrophoresis. The P-B design was used to simultaneously investigate the following five factors: buffer ionic strength, buffer pH, heptakis (2,3,6-tri-o-methyl) beta-cyclodextrin (TMCD) concentration, methanol concentration and injection time, each at three levels. In addition to these, a dummy variable was added to estimate the variability of the system. Effects on resolution and analysis time were calculated. Based on the information gained from the P-B design, the following set of conditions was chosen: 100 mM phosphate buffer pH 2.3, 5 mM TMCD, 5% methanol, and 1.7 s hydrodynamic injection time. These conditions gave well-resolved peaks for zuclomiphene and enclomiphene.