Electrospray Ionisation Mass Spectrometric (ESI MS) Screening and Characterisation of Beryllium Complexes with Potentially Encapsulating Aminopolycarboxylate and Related Ligands

A fundamental issue in beryllium research is the search for suitable chelating ligands for environmental and biomedical application. In this paper, the speciation of beryllium ions with several multidentate aminopolycarboxylic acids, which are well-known commercial and biomedical chelating agents, has been investigated using electrospray ionisation mass spectrometry (ESI MS). Stoichiometric information, which was readily obtained from the ESI mass spectra, was found to be effective for the preliminary screening of potential encapsulation by tetradentate coordination from a single ligand. Ions observed by ESI MS revealed that the pre-existing solution species and binding affinity trends were preserved into the gas phase in good agreement with previous solution speciation data, suggesting the ability of ESI MS to be developed as a quick, sensitive and safe screening technique to observe beryllium speciation with ligands of interest at low concentrations. The disruption of beryllium-ligand binding by addition of other di- or trivalent metal cations is also reported.