Preliminary investigation of aluminium fluoride complexes in aqueous solutions with capillary electrophoresis coupled with electrospray ionization mass spectrometry and with inductively coupled plasma mass spectrometry.

Rationale: It is crucial to identify and confirm the original species of aluminium ions (Al ) dissolved in water, since they behave differently. Depending on their species, the toxicity differs. Capillary electrophoresis (CE) coupled with electrospray ionization mass spectrometry (ESI-MS) and CE coupled with inductively coupled plasma mass spectrometry (CE/ICP-MS) were explored to identify and determine simple systems of Al species solutions at pH 3.0.

Methods: The new combinations of techniques, namely, ESI-MS coupled with CE for identification of species and ICP-MS coupled with CE for confirmation, were applied to for the analyses of Al and fluoride (F) solutions.

Results: Al monomers, some Al dimers and trimers were detected by CE/ESI-MS. CE/ICP-MS experiments were conducted with the assembled interface. As a result, the calibration line showed R  = 0.9856, and the detection limits were 35 nL and 0.037 μM. The results were compared with data obtained using MINEQL+.

Conclusions: Most of the Al species detected were monomers; some dimers and trimers were detected by CE/ESI-MS, but they were not detected by CE-ICP-MS, probably owing to extremely low concentrations. The Al speciation technique was improved by CE/ESI-MS, and the Al species present at extremely low concentrations were ascertained by CE/ICP-MS. The use of coupled instruments will be one of the most powerful tools for identifying dissolved metal ions.