Conversion of chromium(III) propionate to chromium(VI) by the Advanced Oxidation Process Pretreatment of a biomimetic complex for metal analysis.

The use of H(2)O(2) and UV irradiation to remove organic ligands in a chromium(III) complex for the subsequent chromium analysis is reported. The Advanced Oxidation Process (AOP) using a 5.5-W UV lamp, H(2)O(2) and Fe(2+)/Fe(3+) as catalyst (photo Fenton process) was found to give complete and quantitative Cr(III)-->Cr(VI) conversion and removal of ligands in chromium(III) propionate [Cr(3)O(O(2)CCH(2)CH(3))(6)(H(2)O)(3)]NO(3), a biomimetic chromium species, as subsequent chromium analyses by the 1,5-diphenylcarbazide method and atomic absorption revealed. The current process eliminates the need for mineralization and/or dissolution of the matrix in order to remove the organic ligand, the traditional pretreatments of a sample for metal analysis. Studies to optimize the conditions for the oxidation processes, including the use of Fe(2+)/Fe(3+) catalyst, length of UV irradiation, H(2)O(2) concentration, pH, power of UV lamp, and reactor size, are reported.