Arsenic speciation using capillary zone electrophoresis with indirect ultraviolet detection.

The toxicological or biological importance of many trace elements in biological and environmental samples depends to a great extent on their quantities as well as their oxidation states and chemical forms. In this work, arsenic species (arsenate, arsenite, dimethylarsinate [DMA], and monomethylarsonate [MMA]) are determined using capillary zone electrophoresis (CZE) with indirect ultraviolet absorption detection. Sodium chromate is used as an electrolyte solution and to provide the chromophore. The effect of the pH of the solution on the separation of species of interest is discussed. The absolute detection limits are 5.2, 3.5, 15.6, and 15.6 pg for arsenate, arsenite, monomethylarsonate, and dimethylarsinate, respectively. A solution extracted from coal fly ash is analyzed using this method. The arsenate concentration is determined to be 5 micrograms/g. Arsenite, monomethylarsonate, and dimethylarsinate are not found. The advantages of using CZE as an efficient and sensitive separation method are discussed.