[Enantioseparation of chlorpheniramine and EMD-56431 by micellar electrokinetic capillary chromatography using...

Two chiral drugs of EMD-56431 and chlorpheniramine are separated by cyclodextrin-modified micellar electrokinetic capillary chromatography using beta-cyclodextrin(beta-CD) and sodium deoxycholate(SDC) as selector in the paper. All the electrolytes in experiments contain 0.1 mol/L borate. The length of capillary is 45.0 cm as total and 30.0 cm as effective. The running and loading voltages are all 7.8 kV. The effects of pH and concentrations of SDC and beta-CD are studied, in which the best chiral separation conditions for EMD-56431 are pH 10.4, [beta-CD] = 50 mmol/L, [SDC] = 150 mmol/L, and those for chlorpheniramine are pH 9.0, [beta-CD] = 50 mmol/L, [SDC] = 100 mmol/L. The mechanism of chiral separation for the buffer system is initially believed as: the micellar monomer exists almost all as inclusion body with beta-CD, some CD-SDC inclusion complex may exist in micellar because the SDC micellar's gather number is only 4 and the SDC molecular is so big that it can only partly enter beta-CD. Then, the good separation ability of the system is supplied while the ratio of concentration between SDC and beta-CD is in 4:1-4:3; but there will be a optimized total concentration for SDC and beta-CD. The complex interaction among sample, SDC and beta-CD makes intricate change for migration along with the selector's concentration, and the same complex results are also made in pH experiments because of electroosmosis and the acidity of SDC and components. The phenomenon of increasing beta-CD solubility is showed. The beta-CD's solubility with 100 mmol/L SDC can be increased above 150 mmol/L.