“…The speciation of metals in environmental samples is critical for assessing their potential environmental impact before disposal (1,2). In particular, the accurate determination of different ionic species of elements at trace levels, such as Cr(III) and Cr(VI), Sb(III) and Sb(V), or As(III) and As(V), is very important because each ionic species has a different toxicology (3)(4)(5)(6). Because of the different toxicology of Cr(III) and Cr(VI), the speciation study of chromium is very important (7)(8)(9)(10).…”