Separation of Halo-Acetic Acids and Structurally Related Compounds by Capillary. Zone Electrophoresis
卤代乙酸及其结构相近化合物的高效毛细管电泳分离

Chromatographic separation of halo-acetic acids is difficult because of their closely related structure and ionic property. In this paper, we describe capillary zone electrophoresis (CZE) separation of these structurally related compounds. These UV non-absorptive anions were detected indirectly. Phthalate or p-hydroxyl benzoate was chosen as "background absorption agent" for indirect detection. Cetyltrimethylammonium bromide (CTAB) was used as electroosmotic flow (EOF) reverser. The separation was performed in both acidic and basic electrolyte buffers. Separation conditions, such as buffer pH, the concentration of CTAB, capillary temperature and run voltage. were optimized by using orthogonal design. At the optimal conditions, halo-acetic acids were nearly baseline-separated in acidic or basic buffer. The separation selectivity of organic acids is improved in acidic (5mmol/L) phthalate buffer, as compared with basic ammonium buffer. The resolution is improved at lower running voltage (10kV/50cm). This does not agree to the common rule for CZE resolution and the reason is unknown at present.