Quaternary phosphonium-based (TPQPCl)-ionomer/graphite nanoplatelets composite chemically modified electrodes: A novel platform for sensing applications

Ionomers have attracted considerable interest in electroanalysis due to the possibility of fabricating electrode coatings capable of preconcentrating sub-micromolar concentrations of cations or anions of analytical relevance. In this work, we describe the electroanalytical performances of an ionomer (TPQPCl)/graphite nanoplatelets composite material towards the development of an amperometric sensor for detection of ascorbic acid. Graphite nanoplatelets at different concentrations were dispersed in ethanolic solutions containing TPQPCl. The as-prepared TPQPCl/graphite nanoplatelet-coated electrodes were characterised using Fe(CN) ₆ ^4-/3- as an anionic redox probe. The results evidence the good preconcentration capability of the positively charged TPQPCl towards the incorporation of negatively charged species. By tuning the ionomer/graphite nanoplatelets ratio, it is possible to detect simultaneously ascorbic acid even in the presence of dopamine as an interference species. The TPQPCl/graphite nanoplatelet-coated electrodes were able to detect ascorbic acid in the linear range of 5-10000 μM with a limit of detection calculated as 4.8 μM using linear sweep voltammetry. Finally, the TPQPCl/graphite nanoplatelet-coated electrodes were tested towards detection of ascorbic acid in vitamin C tablets and orange juice without any sample pretreatment.