Recovering Ga(III) from coordination complexes using pyridine 2,6-dicarboxylic acid chelation ion chromatography

Area of Science:

• Analytical Chemistry
• Coordination Chemistry
• Biogeochemistry

Background:

• Ion exchange chelation chromatography is valuable for metal extraction from complex matrices.
• Limited data exists on the types of metal complexes amenable to this chromatographic analysis.
• Gallium(III) (Ga(III)) analysis is crucial in various scientific fields.

Purpose of the Study:

• To evaluate pyridine 2,6-dicarboxylic acid (PDCA) for extracting and quantifying Ga(III).
• To assess PDCA's effectiveness across diverse sample matrices and coordination environments.
• To compare PDCA chelation with established methods like inductively coupled plasma mass spectrometry (ICP-MS).

Main Methods:

• Utilized standard liquid chromatography apparatus with PDCA for Ga(III) chelation.
• Determined Ga(III) peak characteristics: retention time, precision, and limit of detection.
• Cross-validated the PDCA method against ICP-MS using Ga(III) hydroxide complexes.

Main Results:

• The PDCA method yielded a consistent Ga(III) peak (2.55 ± 0.02 min) with high precision (<2%) and a detection limit of 110 µM.
• Successful cross-validation with ICP-MS was achieved for Ga(III) hydroxide complexes (stability constant 15.66).
• PDCA efficiently extracted Ga(III) from porcine mucus (96.9 ± 1.2%) and citrate complexes (100.7 ± 2.7%), but less effectively from EDTA complexes (ca. 50%).

Conclusions:

• PDCA chelation chromatography is a suitable alternative to ICP-MS for quantifying Ga(III).
• The method is effective for Ga(III) in biological samples and weakly to moderately coordinated complexes (stability constant <15).
• Strongly coordinated Ga(III) complexes (stability constant >15) may require alternative analytical approaches.