The formation and properties of mixed lead sulfide—silver sulfide membranes for lead(II)-selective electrodes

The preparation and behaviour of a lead(II)-selective electrode made of mixed silver sulfide-lead sulfide are discussed and compared with those of a copper(II)-selective electrode. X-ray diffraction showed that hot-pressing of the membrane causes changes in the crystalline structure of the material. Responses to lead(II), sulfide, and hydroxide were measured ; potential-pH curves were determined in solutions containing EDTA, NTA, Tetren or Trien with and without the lead complex. The results are similar to those obtained for the copper-i.s.e. Data are given for titrations, selectivity coefficients, and response times. The response of the lead-i.s.e. to an addition of ligand is faster for Trien than for EDTA. This difference is large for the copper-i.s.e. These response rates may be correlated with potential-pH curves in the presence of ligands.