An ion-selective electrode with a polymeric membrane containing an active chelating substance

An optimal new PVC membrane sensor for Cd2+ ions based on TRIAR 3-(2’,4’dihydroxyphenylazo-1’)-1,2,4 triazol as the active substance was prepared. Its basic analytical parameters such as slope characteristics; detection limit; lifetime; response time; selectivity for zinc, nickel, cobalt, calcium, copper, barium, magnesium, manganese, potassium and sodium ions, as well as the dependence of the electrode potential on pH were established. The proposed membrane sensor can be used in flow injection potentiometric analysis of cadmium ions.

The application of TRIAR in the polymeric membrane phase as an active substance creates an electrode selective for cadmium. This electrode is characterized by good analytical parameters: a theoretical characteristic slope 28.5 mV/pa, low detection limit (5.9×10!6 M), wide pH range (4.3–8.5), short response time (5 s) and a very long lifetime: about 7 months. The electrode selectivity coefficients for inter-fering ions (Zn2+, Co2+, Ni2+, Mg2+, Ba2+, Cu2+, Mn2+, Fe2+, K+, Na+) are sufficient. The proposed Cd(II) membrane sensor was successfully applied in flow injection potentiometric measurements of Cd(II) ions. It can be used in laboratories for cadmium determination in the range 10!1–5.9×10!6 M, its use shortens the time of conducted analyses, especially if an FIA system is applied.