Lead electrodes are potentiometric devices used for the rapid determination of free lead ions in plating baths and as a detector for the titration of sulfate or thorium with lead perchlorate. Lead sensors are “electrodes of the third kind” because they detect cations which also form low-solubility salts with sulfide anions and forms low-solubility salts with silver.
The lead ISE is a mixed lead sulfide/silver sulfide membrane produces a potential change due to changes in the sample’s lead ion activity. When the ionic strength of the sample is fixed by the addition of ISA, the voltage is proportional to the concentration of lead ions in solution and the electrode follows the Nernst equation. The lead ISE is available as a combination electrode with both indicating half cell and reference half cell or available as an indicating half cell that will be used with a separate reference half cell.