Towards improving the electroanalytical speciation analysis of indium

Area of Science:

• Environmental Science
• Analytical Chemistry
• Geochemistry

Background:

• Indium's geochemical fate in natural waters is poorly understood.
• Growing environmental input of indium due to high-technology manufacturing.
• Need for reliable analytical tools for indium speciation.

Purpose of the Study:

• To develop and validate electroanalytical techniques for indium speciation.
• To measure total and free indium concentrations in solution.
• To assess indium binding with natural organic matter.

Main Methods:

• Utilized two complementary electroanalytical techniques: Stripping chronopotentiometry (SCP) and Absence of Gradients and Nernstian Equilibrium Stripping (AGNES).
• Employed Thin Mercury Film/Rotating Disk Electrode (TMF/RDE).
• Investigated indium-oxalate systems and indium binding with humic acids.

Main Results:

• Achieved nanomolar limits of detection (0.5 nM for SCP, 0.1 nM for AGNES).
• AGNES provided robust speciation data for known indium-oxalate systems.
• Elaborated indium binding isotherms over four decades of free indium concentrations with humic acids.

Conclusions:

• Developed sensitive electroanalytical methods for indium speciation.
• These techniques offer new possibilities for using indium as a tracer for trivalent element biogeochemical processes.
• Advancements in understanding indium's environmental behavior and fate.