Electrospray-Ionisation Mass-Spectrometric (ESI-MS) Investigation of Beryllium Hydrolysis in Acidic Solutions of Beryllium Sulfate

The speciation and hydrolysis of beryllium ions in an aqueous solution of its sulfate salt have been studied over a pH range of 2.5-6.0 by using electrospray ionisation mass spectrometry (ESI-MS). Ions observed by ESI-MS revealed that the highly charged beryllium hydroxido species in solution were preserved into the gas phase by pairing with the sulfate ion. The pH-dependent hydrolytic tendencies of the Be2+ cation presented as an ESI-MS speciation diagram were in good agreement with previous 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. Collision-induced dissociation patterns further supported the trimer [Be-3(OH)(3)](3+) as the most stable beryllium hydroxide species arrangement while the pronounced association of the beryllium cation and sulfato ligand yielded additional beryllium cluster arrangements such as {Be-3(mu(3)-O)} clusters and mixed sulfato/hydroxido species such as [Be3O(HSO4)(3)](+).