Hydrogen peroxide measurement modified electrode

We report here the results obtained by the use of a screen-printed electrode as electrochemical probe to be coupled with a microdialysis fibre for continuous glucose monitoring. The most significant advance is represented by the introduction of a mediator (PB) as the principal factor for hydrogen peroxide measurement. The improved operational stability observed with the PB-modified screen-printed electrodes has demonstrated that these sensors could serve as tool to be applied for the continuous monitoring of many analytes. The application to diabetic care seems to be the most promising and advantageous area in which to test these sensors. 

ChemicaUy Modified Electrode for Hydrogen Peroxide Measurement by Reduction at Low... 

These modified electrodes did not create voltammetric signals in the presence of PHGPx alone or after incubation of PHGPx with hydrogen peroxide as measured between + 500 and - 600 mV. However, a distinct reduction current was induced by the addition of GSH to PHGPx preincubated with hydrogen peroxide. This was manifested by the appearance of a wave in the cyclic voltammogram at a potential of -280 mV (Fig. 2.8). This is in contrast to the behaviour of heme peroxidases. 

The above measuring principle has been modified for the measurement of HRP substrates which are themselves electrochemically active. To avoid electrochemical interference a Clark-type oxygen probe was used together with catalase coimmobilized with GOD. The hydrogen peroxide not consumed by HRP is cleaved by catalase to oxygen which is indicated at the electrode. Consequently, the biochemical basis of the sensor is the competition of HRP and catalase for the common substrate, H202. 

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