Selective ultratrace detection of Al(III) and Ga(III) complexed with a calcein isomer by capillary zone electrophoresis with laser-induced fluorescence detection: Comparison of emissive polyaminocarboxylates as derivatizing ligands

A highly sensitive and selective capillary zone electrophoresis with laser-induced fluorescence detection (CZE-LIF) for Al3+ and Ga3+ was developed using a calcein 4′,5′-isomer as a pre-capillary complexing agent. Direct fluorescent detection without an agent added to the carrier buffer provided the notable detection limits of 3.9 × 10−10 and 4.6 × 10−10 mol dm−3 for Al and Ga, respectively. By applying this system successfully to a river water sample, its potential for practical applications was ascertained. A comparison of three aromatic polyaminocarboxylate ligands related to the coordination structure and the distance between the fluorophore and the chelating moiety, revealed some interesting factors regarding their selectivity.