Calibrationless pH sensors based on nitrosophenyl and ferrocenyl co-modified screen printed electrodes

The pH sensing capability of surface confined nitrosophenyl groups is demonstrated. Nitrosophenyl modified edge plane pyrolytic electrodes (EPPGs) and screen printed electrodes (SPEs) were characterised by cyclic voltammetry and square wave voltammetry respectively. A near-Nernstian response of 59 mV/pH at 25 °C, was obtained. A pH insensitive internal reference, ferrocenyl group was co-modified onto the nitrosophenyl modified screen printed electrodes. Calibrationless pH measurement was realised using the difference in the redox potentials of the pH dependent nitrosophenyl and pH insensitive ferrocenyl groups.