Migration behavior of niacin derivatives in capillary electrophoresis

The migration behaviour of niacin derivatives was investigated by capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC). When the pH of the buffer solution is lower than the pK_a of the pyridine ring in the niacin derivatives, they are positively charged by protonation on the pyridine ring and migrate electrophoretically. The mobilities of niacin derivatives in CZE were controlled by the pH of the migrating buffer. Good separation of thirteen niacin derivatives was achieved at pH 2.8. Further, to shorten the analytical time and to achieve a more complete separation, an investigation by MEKC using sodium dodecyl sulfate micelles was performed. All thirteen niacin derivatives were eluted within 30 min and a satisfactory separation was achieved.