Siberian Federal University

A method for the selective preconcentration of Cr(VI) using a silica gel-based sorbent chemically modified with methyltriphenylphosphonium groups, followed by determination by inductively coupled plasma atomic emission spectroscopy or a test-method has been proposed. Cr(VI) is effectively removed by the sorbent in the pH range of 3.5–5.5. In this pH range, there is no sorption of Cr(III), which makes it possible to effectively separate Cr(VI) from Cr(III). When a solution containing Cr(VI) is passed through a column with a sorbent, a yellow-colored zone appears in the column, the length of which is proportional to the Cr(VI) content in the column. Cr(VI) can be quantitatively desorbed with 5 mL of 2M HCl and determined in the eluate by inductively coupled plasma atomic emission spectrometry. The sorbent withstands at least 20 “sorption-desorption” cycles. The efficiency of separation and the accuracy of adsorption-atomic-emission and test- determination of Cr(VI) were confirmed by “added-found” method and by analysis of water samples with chromium content determined using a certified method