Electrochemiluminescence Determination of Mo(Ⅵ) Content in Beans Based on Polyluminol Composite Modified Electrode

In this study, based on the sensitization effect of Mo(Ⅵ) on luminol electroreduction luminescence signals, combined with the amplifying effect of graphene and positively charged gold nanoparticle ((+)AuNPs), a novel electrochemiluminescence method for sensitive and accurate detection of Mo(Ⅵ) content in legumes seeds was established. The Nafion-graphene/(+)AuNPs/polyluminol composite modified electrode was firstly prepared by the drip coating method, and then (+)AuNPs and luminol were modified on the surface of the Nafion-graphene composite electrode by electrostatic assembly and electrochemical polymerization technology. The composite modified electrode was characterized by cyclic voltammetry and ECL technology, and the experimental conditions for determination of Mo(Ⅵ) were optimized. The results showed that the optimal experimental conditions for the determination of Mo(Ⅵ) were saturated borax buffer solution, potential scanning rate of 100 mV/s and concentrated time of 13 minutes. Under the selected conditions, the concentration of Mo(Ⅵ) was well linear with the enhancement of electroreduction luminous signal in the range of 5.0×10⁻⁹~1.0×10⁻⁶ mol/L. Detection limit of the method and relative standard deviation (RSD) was 2.1×10⁻⁹ mol/L (3σ, C=1.0×10⁻⁷ mol/L, n=11) and 2.4%, respectively. This method had been applied to the detection of Mo(Ⅵ) content from soybean and mung beans. The recovery rate was between 91.42% and 108.0%. This proposed method is simple and economical, and is expected to be applied to the accurate determination of Mo(Ⅵ) content in other beans seeds.