Recessing reduces oxygen sensitivity of the antimony pH microelectrode (physiology application)

The electromotive force (EMF) of antimony pH microelectrodes is oxygen-dependent, which degrades their performance. Oxygen sensitivity was experimentally determined for a factorial combination of (a) recessing the electrode tip, (b) saturating the medium with antimony oxide, and (c) buffering the medium with phosphate. After the baseline pH sensitivity in phosphate buffers was established, the EMF was measured while the equilibrating gas was varied selectively from 5% to 21% oxygen. Oxygen sensitivity of unrecessed electrodes was larger than that of recessed electrodes. The effects of saturating the medium with antimony oxide and of buffering on oxygen sensitivity were not significant. Loss of electroplated antimony from the tip of the electrode was associated with a positive shift in E/sub 0/.<>