engleski

Electrochemical Determination Of Ascorbic Acid On A Silica Nanosphere/Graphene Composite Modified Graphite Electrode

A large number of scientific papers have demonstrated the health benefits of consuming healthy food that contains significant amount of antioxidants. Fruits like oranges, lemons or kiwi are an important source of water-soluble antioxidants in a diet, but their content may change during storage [1], this is why the determination of water-soluble antioxidants like vitamin C has great practical importance. In this work, we present the influence of surface modification of the working electrode with composite materials on analytical performance in the determination of ascorbic acid by cyclic voltammetry. We have tested the analytical performance of the graphite electrode modified with commercially available Carbon graphene ink (Gwent group, UK). The Carbon graphene ink (CGI) was mixed with monodisperse solid nonporous silica nanospheres with the attempt to increase the active surface area and to provide homogenous porous structure for controlled diffusion of electroactive species. The surface modification of supporting graphite electrode (d=0.5 mm), was performed by drop casting of the CGI. After drying, the electrode was polished on lint-free paper. Spherical nonporous silica nanoparticles (SNPs) were synthesized by a modified method established by Stöber, Fink and Bohn [2]. The composite material was made by mixing SNPs with carbon graphene ink, where the mass ratio of graphene and SNPs was 1:1. The comparison was made between working electrodes modified with CGI ink and CGI/SNPs composite material. Addition of SNPs remarkably enhanced the peak currents of ascorbic acid. Graphene is already known for improving analytical performance and direct electron transfer at the graphene/electrolyte interface when used as a component of electroanalytical devices but with the addition of SNPs, we enhanced the active surface, because of SNPs large specific surface area. The composite material has promising analytical properties and can be used for the production of low-cost screen-printed electrodes for direct determination of ascorbic acid in the food products.

ascorbic acid ; silica ; graphene ; graphite electrode

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