title: Colorimetric Detection of Sulfite in Foods by a TMB-O2-Co3O4 Nanoparticles Detection System.
abstract: In this paper, we first discovered that Co3O4 nanoparticles (NPs) possess intrinsic oxidase-like activity and can catalytically oxidize peroxidase substrates, such as 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and 3,3',5,5'-tetramethylbenzidine (TMB), to form colored products, in the absence of exogenously added H2O2. The presence of sulfite inhibited the TMB-O2-Co3O4 NPs reaction system and caused a change in color of the reaction system. On the basis of this phenomenon, a colormetric approach to detect sulfite was established with a good linear relationship ranging from 0.2×10(-6) to 1.6×10(-5) M and a detection limit of 5.3×10(-8) M. The method was used to detect sulfite in foods. Good recoveries ranging from 93.8% to 100.5% were obtained. Furthermore, the mechanism was studied and results showed that the oxidase-like activity of the Co3O4 NPs was not from •OH or O2•- radical generated. It may probably originate from their ability to transfer an electron between the peroxidase substrate and oxygen absorbed on the surface of the Co3O4 NPs.
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University , Lanzhou 730000, China.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Qin
authors.forename: Li
authors.initials: L
authors.lastname: Su
authors.forename: Chen
authors.initials: C
authors.lastname: Yang
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Ma
authors.forename: Haijuan
authors.initials: H
authors.lastname: Zhang
authors.forename: Xingguo
authors.initials: X
authors.lastname: Chen
mesh_terms: D001560:Benzidines / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D003124:Colorimetry / Q000295:instrumentation / Q000379:methods*; D005504:Food Analysis; D005520:Food Preservatives / Q000032:analysis*; D053758:Nanoparticles / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D013447:Sulfites / Q000032:analysis*
chemical_list: D001560:Benzidines; D005520:Food Preservatives; D010087:Oxides; D013447:Sulfites; C021758:3,3',5,5'-tetramethylbenzidine; D003035:Cobalt; D010100:Oxygen; C060728:cobalt oxide