Electrochemical gas sensor for detecting high phosphine concentrations

A process for determining a concentration of an analyte gas comprising a hydride compound, wherein the process comprises the steps of:

• admitting the analyte gas to an electrochemical gas sensor, wherein the electrochemical gas sensor comprises at least a first working electrode, a second working electrode, a counterelectrode, a reference electrode arranged between the first working electrode and the second working electrode and an electrolyte, which is in conductive contact with the first working electrode, with the second working electrode, with the counterelectrode and with the reference electrode;
• applying an electrical voltage between the first working electrode and the reference electrode;
• applying an electrical voltage between the second working electrode and the reference electrode;
• at least partial oxidation of partially oxidizing the analyte gas at the first working electrode,
• wherein at least one reaction product migrates to the counterelectrode,
• at least partially reducing oxygen at the counterelectrode, and
• measuring of the current flowing between the first working electrode and the counterelectrode.