AB-101

Complexometric titrations with the copper-selective electrode

Summary

This Application Bulletin describes complexometric and potentiometric determinations of metal ions using the copper-selective electrode (Cu-ISE) by EDTA titration. The electrode consists of a robust, break-proof plastic shaft made of epoxy resin and a crystal membrane. As this electrode does not respond directly to complexing agents, the corresponding Cu complex with the metal ions must be added to the sample solution.

This method can be used to titrate metal ions by either direct or back-titration. The principle is based on the formation constants between ethylenediaminetetraacetic acid and metal ions which form stable complexes. These chemical reactions lead to an equivalence point. The copper-selective electrode, in combination with a reference electrode, can be used to determine the following: water hardness, metal concentrations in rare earth elements (REEs), electroplating baths, metal salts, minerals, and ores. The following metal ions can be analyzed (this list is not exhaustive):

Al³⁺, Ba²⁺, Bi³⁺, Ca²⁺, Co²⁺, Cd²⁺, Cu²⁺, Fe³⁺, In³⁺, Mg²⁺, Mn²⁺, Ni²⁺, Pb²⁺, Sr²⁺, Tl³⁺, Zn²⁺, Zr⁴⁺ and the REEs which include Sc³⁺, Y³⁺, as well as the lanthanides.