A comment on arsenic species separation using ion exchange

The Ficklin anion exchange method for separation of arsenate and arsenite is a solution to the problem of preservation of arsenic species. Ion exchange separations, in the field, of arsenite and arsenate are necessary because there are not suitable sample preservation methods that will maintain the arsenate/arsenite ratio, or suitable field separation techniques other than ion exchange. Ion exchange separations were performed on the four arsenic species common in drinking water sources using the Ficklin method. The common organic arsenic species elute with arsenite. This implies that the use of the Ficklin method to speciate waters bearing organic arsenic will have the undesirable consequence of falsely indicating higher concentrations of the most toxic form of arsenic.