Release of copper from commercial solid-state copper ion-selective electrodes.

Area of Science:

• Electrochemistry
• Analytical Chemistry

Background:

• Solid-state ion-selective electrodes (ISEs) are crucial for measuring ion concentrations.
• Copper ion-selective electrodes (Cu-ISEs) are susceptible to copper leaching, potentially affecting measurement accuracy.
• Understanding copper release mechanisms is vital for optimizing ISE performance.

Purpose of the Study:

• To quantify copper release from two commercial Cu-ISEs in various media.
• To investigate factors influencing copper dissolution, including media composition and oxygen levels.
• To evaluate the effectiveness of a cation-exchange membrane in mitigating copper release.

Main Methods:

• Immersion of Orion 94-29 Cupric Electrode and Radiometer F1112 Selectrode in 0.1M KNO3, 0.5M NaCl, and 0.1M HNO3.
• Measurement of released copper concentrations.
• Testing the effect of oxygen removal and Nafion coating on copper release.
• Investigation of the copper dissolution mechanism.

Main Results:

• Copper release from both electrodes interfered with cupric ion determination at the 10(-7)M level in 0.1M KNO3.
• Copper release increased in 0.5M NaCl and 0.1M HNO3 for electrode II, but not electrode I.
• Oxygen levels did not affect copper release.
• Coating electrodes with a Nafion membrane substantially reduced copper release.

Conclusions:

• Commercial Cu-ISEs can release significant amounts of copper, causing interference in trace analyses.
• Electrode design and media composition influence copper dissolution.
• Nafion coating is an effective method to minimize copper release and improve the reliability of Cu-ISE measurements.