Continuous pH monitoring with monocrystalline antimony electrodes: toxicity considerations from studies on...

Monocrystalline antimony electrodes can be used as pH sensors for continuous monitoring in vivo. The electric potential of the electrodes stems from a corrosion reaction in which antimony metal dissolution constitutes the anodic reaction. In this study the amount of antimony which leaves a monocrystalline antimony sensor, when monitoring pH in thermostatically controlled sterile human heparinized plasma, was determined by neutron activation analyses. From these results the toxicity hazard of using such electrodes in vivo is assessed. It is concluded that the amount of antimony released from a monocrystalline pH sensor, when used in a biological medium, is small compared with the amount of antimony accepted for administration as a medical therapeutic. Thus it should be safe from the toxicological point of view to use monocrystalline antimony electrodes for in vivo pH monitoring.