Flow injection analysis of ascorbic acid based on its thermoelectrochemistry at disposable screen-printed carbon electrodes

The thermoelectrochemistry of ascorbic acid (AA) at a disposable screen-printed carbon electrode (SPE) was studied in this paper. The response of AA is greatly suppressed at higher temperatures when the electrolyte solution containing AA is directly heated. On the other hand, as a light beam is applied to heat an SPE, it is interesting that the heated electrode is capable of increasing the detection sensitivity without decomposing the substrates. It is further applied for flow injection analysis (FIA) of AA by using a specifically designed electrochemical cell coupled with the disposable SPE. Possible reason for the enhancement in oxidation peak intensity at elevated temperature by the proposed heated electrodes operating in a non-isothermal mode is examined through in situ impedance technique as well as diffusion coefficient measurement by cyclic voltammetry. The slope of calibration plot obtained at elevated temperature (∼46 °C) is 0.034 μA/μM, which is ∼1.5 times improved than that at room temperature. Applicability in real sample shows in good agreement with the quoted value as well as the results observed by other methods.