Spectrophotometric determination of hexafluoroarsenate with ferroin

A spectrophotometric method for the hexafluoroarsenate anion is described. The determination involves selective extraction of the tris(1,10-phenanthroline)iron(II) salt of the anion into n-butyronitrile, followed by measurement of the absorbance of the organic layer. The extracts give good Beer's law plots over a wide range of concentrations and more than 98% of the hexafluoroarsenate is removed in a single extraction. Interference studies were made on a number of anions.