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.

Abstract

It is crucial to identify and confirm the original species of aluminium ions (Al3+ ) 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. 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. 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 R2 = 0.9856, and the detection limits were 35 nL and 0.037 μM. The results were compared with data obtained using MINEQL+. 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.