Complex lanthanide-PDCA

For the determination of lanthanides in geological samples, a problem arises regarding the co-elution with excess amounts of heavy and transition metals. For an improved separation between both classes of compounds, one capitalizes on the different com-plexing behavior of heavy metals and rare-earth elements with pyridine-2,6-dicarboxylic acid. Heavy and transition metals form stable monovalent and divalent complexes with PDCA, while the complexes of lanthanides with PDCA are trivalent ... 

Analysis of certain sample matrices can be difficult because of coelution problems occurring when some transition metals are present in much higher concentrations. Luckily, while transition metals form stable monovalent and divalent complexes with PDCA, lanthanides complexes with PDCA are bivalent. 

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