Studies with the "Severinghaus" PCO2 electrode I: electrode stability, memory and S plots.
A study of the Radiometer "Severinghaus" Pco2 electrode has been made in order to investigate its stability and reproducibility when exposed to a series of inknown gas samples of various carbon dioxide concentrations. Electrodes were found to exhibit a pronounced memory effect, which depended upon the Pco2 of the last sample to which they had been exposed if the exposure had been for more than a few minutes. When a number of electrodes were exposed to a single reference gas at all times, except for the few minutes required to measure the Pco2 of an unknown sample, the electrical output of the electrode was unexpectedly stable and reproducible. This implies a high degree of measurement accuracy. If the reference gas to which the electrode is usually exposed is of low carbon dioxide concentration, the electrode displays its highest degree of stability and reproducibiltiy. The use of low carbon dioxide content reference gases is not always convenient, however, because they increase the response time of the electrode. Reference gases of high carbon dioxide content induce unstable electrode behaviour, and so it is recommended that gases higher than 5% v/v Co2 are not chosen for this purpose.
D002245:Carbon Dioxide / Q000032:analysis*; D004566:Electrodes; D005740:Gases / Q000032:analysis; D008568:Memory; D010313:Partial Pressure
D005740:Gases; D002245:Carbon Dioxide