Electrochemical improvement of the performance of PO2 electrodes.

Rotating ring-disc electrode studies have indicated that relatively large quantities of hydrogen peroxide ion, HO2-, are produced when oxygen is reduced at a platinum or gold polarographic electrode surface. The electrochemical reduction processes are improved and the quantity of HO2- is reduced by using alkaline buffer electrolytes (pH 10 to 11) and by polarising the electrode at voltages more negative than -0.9 V. The presence of HO2- in the electrolyte has been shown to be the cause of excessively long time response in both blood-gas and respiratory polarographic PO2 electrodes; electrode alinearity on micro-blood-gas PO2 electrodes has also been shown to be due to the absence of a plateau on the polarogram of electrodes when used with conventional electrolytes. The use of a high pH buffer and high negative voltage results in a long, flat plateau and a marked improvement in both electrode linearity and response time. This two-fold improvement in electrode performance holds true for both platinum and gold polarographic respiratory gas and blood-gas PO2 electrodes.