Electrochemical Sensor for Dissolved Carbon Dioxide Measurement

In this paper, the fabrication and evaluation of a Severinghaus-type sensor, based on an iridium oxide pH electrode, are described. An iridium oxide pH electrode and an Ag/AgCl reference electrode were housed inside a gas-permeable silicone rubber tubing in which a bicarbonate-based electrolyte solution was sealed. The internal pH electrode was produced by a new method, i.e. , the pH-sensitive film was coated on the surface of an Ir metal wire by oxidation of the Ir wire in a carbonate melt at high temperature. The Ag/AgCl reference electrode was prepared by chloridizing an Ag wire in a solution. The sensor made this way showed Nernstian response to dissolved in the range to Superior analytical accuracy and stability were observed for the sensor.