Separation of arsenic anions by capillary zone electrophoresis with UV detection

Summary Capillary zone electrophoresis (CZE) in capillary silica columns has been used for the separation of arsenite (AsO ₂ ^– ), arsenate (AsO ₄ ^3– ), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The separation of these ionic species has been achieved using a capillary silica column (72 cm×50 m i.d.) with an acidic phosphate buffer and with an on-column UV detection (190 nm). Optimization of experimental parameters (pH, temperature, voltage) were studied. The selectivity of the separation can be improved by working in the pH-range of 4.5–6.5. For analytical inorganic separations of UV-absorbing anions, capillary zone electrophoresis has advantages because of the relatively simple equipment, the short analysis time (15 min), the high efficiency and the low mass detection limit (40 pg for arsenate).