Chemical methods screen-printed electrodes

HPLC with UV-based diode array detection (DAD-UV) or electrochemical detection is normally used to determine ascorbic acid. Many types of electrochemical determinations of ascorbic acid have been proposed. Although the electrochemical determinations using enzyme-based biosensors exhibited high specificity and sensitivity, these methods suffer in the fabrication of the electrodes and in automatic analysis. Recently, chemically modified screen-printed electrodes have been constructed for the determination of ascorbic acid. This is one of the most promising routes for mass production of inexpensive, reproducible, and reliable electrochemical sensors. 

Stability of Prussian blue modified screen-printed electrodes The operational stability of all the PB-modified sensors is a critical point, especially at neutral and alkaline pH. A possible explanation for reduced stability could be the presence of hydroxyl ions at the electrode surface as a product of the H202 reduction. Hydroxyl ions are known to be able to break the Fe-CN-Fe bond, hence solubilising the PB [21]. An increased stability of PB at alkaline pH was first observed by our group after adopting a chemical deposition method for the modification of graphite particles with PB for the assembling of carbon paste electrodes [48]. 

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