A simple and sensitive resonance scattering spectral method for determination of hydroxyl radical in Fenton system using rhodamine S and its application to screening the antioxidant.

ABSTRACT

Based on resonance scattering (RS) effect of rhodamine dye association particles, a new resonance scattering method for the determination of hydroxyl free radical from Fenton reaction was developed. In HCl-NaAc buffer solution, the OH of Fenton reaction oxidized the excess I(-) to I(3)(-). The I(3)(-) combined, respectively, with rhodamine B (RhB), butyl rhodamine B (b-RhB), rhodamine 6G (RhG) and rhodamine S (RhS) to form association particles that exhibit stronger resonance scattering effect at 420nm and 610nm. However, the RS peak at about 610nm was interfered with its synchronous fluorescence peak at 580nm for RhB, 580nm for b-RhB, 560nm for RhG and 560nm for RhS, respectively. The concentration of H(2)O(2) in the range of 0.648-21.6mumol/L, 0.423-13.0mumol/L, 0.216-13.0mumol/L and 0.092-13.0mumol/L was linear to its resonance scattering intensity at 420nm. Its detection limit was 0.15mumol/L, 0.10mumol/L, 0.092mumol/L and 0.044mumol/L, H(2)O(2), respectively. This RhS RS method was applied to selection of the antioxidant, with satisfactory results.