Exploring bufferless iron speciation in seawater by Competitive Ligand Equilibration-Cathodic Stripping Voltammetry:...

Area of Science:

• Environmental Chemistry
• Marine Chemistry
• Analytical Chemistry

Background:

• Iron is crucial for marine primary productivity.
• Accurate iron speciation in seawater is essential for understanding its biogeochemical cycles.
• Traditional methods often require pH buffering, which can alter natural conditions.

Purpose of the Study:

• To develop a novel Competitive Ligand Equilibration-Cathodic Stripping Voltammetry (CLE-CSV) method for iron speciation in seawater.
• To eliminate the need for pH buffers in the CLE-CSV procedure.
• To enable iron speciation analysis at natural seawater pH.

Main Methods:

• Development of an unbuffered CLE-CSV procedure using 2,3-dihydroxynaphthalene as the ligand.
• Validation of the method using known ligands and ultratrace levels.
• Application to seawater samples from the Ross Sea, Antarctica.

Main Results:

• The unbuffered CLE-CSV method reliably determines ultratrace ligand levels.
• Analysis of Antarctic seawater samples yielded results comparable to buffered methods.
• The method allows for pH adjustment at the electrode interface during analysis.

Conclusions:

• The developed unbuffered CLE-CSV method offers a new paradigm for trace element speciation.
• It enables accurate iron speciation at natural pH, even in challenging samples.
• This advancement facilitates a deeper understanding of iron's role in marine ecosystems.