Dual carbonate sensor based on Eu(III) complex of DO3A ligand

Eu(III) ternary complexes with 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (H 3 DO3A) and picolinate-like “antenna” ligands ([Eu(DO3A)(L)] − ) react with carbonate anion to form more stable [Eu(DO3A)(CO 3 )] 2− complexes which are non-fluorescent. Furthermore, [Eu(DO3A)(L)] − and [Eu(DO3A)(CO 3 )] 2− differ in their electrochemical behavior. [Eu(DO3A)(L)] − are therefore suggested as sensitive luminescence-based and also electrochemical sensors of carbonate anion. Both luminescence and voltammetric sensing strategies show similar analytical figures of merit (limit of detection 0.2 mM, dynamic range 0.2–1.6 mM). The voltammetric procedure was successfully tested in field conditions for the quantitative analysis of bicarbonate/carbonate in environmental water samples, utilizing portable potentiostat and screen-printed electrode. Graphical abstract