title: CoFe2O4 nanoparticles as oxidase mimic-mediated chemiluminescence of aqueous luminol for sulfite in white wines.
abstract: Recently, the intrinsic enzyme-like activity of nanoparticles (NPs) has become a growing area of interest. However, the analytical applications of the NP-based enzyme mimetic are mainly concentrated on their peroxidase-like activity; no attempts have been made to investigate the analytical applications based on the oxidase mimic activities of NPs. For the first time, we report that CoFe(2)O(4) NPs were found to possess intrinsic oxidase-like activity and could catalyze luminol oxidation by dissolved oxygen to produce intensified chemiluminescence (CL). The effect of sulfite on CoFe(2)O(4) NP oxidase mimic-mediated CL of aqueous luminol was investigated. It is very interesting that when adding sulfite to the luminol-CoFe(2)O(4) system, the role of sulfite in the luminol-CoFe(2)O(4) NP-sulfite system depends on its concentration. At a relatively low concentration level, sulfite presents an inhibition effect on the luminol-CoFe(2)O(4) NP system. However, it does have an enhancement effect at a higher concentration level. Investigations on the effect of the solution pH and luminol and CoFe(2)O(4) NP concentrations on the kinetic characteristics of the studied CL system in the presence of trace sulfite suggested that the enhancement and inhibition of the luminol-CoFe(2)O(4) NP-sulfite CL system also depended on the solution pH. It seems that the concentrations of luminol and CoFe(2)O(4) NPs did not influence the CL pathway. The possible mechanism of the luminol-CoFe(2)O(4) NP-sulfite CL system was also discussed. On this basis, a flow injection chemiluminescence method was established for the determination of trace sulfite in this study. Under the optimal conditions, the proposed system could respond down to 2.0 × 10(-8) M sulfite. The method has been applied to the determination of trace sulfite in white wine samples with satisfactory results. The results given by the proposed method are in good agreement with those given by the standard titration method.
authors.affiliation: The Key Laboratory of Luminescence and Real-time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Xiaodan
authors.initials: X
authors.lastname: Zhang
authors.forename: Shaohui
authors.initials: S
authors.lastname: He
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Chen
authors.forename: Yuming
authors.initials: Y
authors.lastname: Huang
mesh_terms: D002384:Catalysis; D003035:Cobalt / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry*; D008163:Luminescent Measurements / Q000379:methods; D008165:Luminol; D053758:Nanoparticles; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D013447:Sulfites / Q000032:analysis*; D014920:Wine / Q000032:analysis*
chemical_list: D005296:Ferrous Compounds; D013447:Sulfites; D003035:Cobalt; D008165:Luminol; D010088:Oxidoreductases; C034236:ferrous oxide