Study of thorium hydrolysis species by electrospray-ionization mass spectrometry

Electrospray-mass spectrometry (ES-MS) has been used for the first time to study the hydrolysis of thorium. Hence, important discrepancies exist in th e literature concerning the appearance of the first hydroxo complex. By stu dying thorium species as a function of pH, it was possible to observe the a ppearance of the first thorium hydroxo complexes at pH I as well as the oth er hydroxo complexes at higher pH. By using MS/MS experiments, all thorium complexes corresponding to the different hydroxo thorium species, Th(OH)(3), Th(OH)(2)(2+), Th(OH)(3)(+) were attributed. Speciation of Th-hydrolyzed complexes obtained by ES-MS is compared to that obtained in the literature . (C) 2001 Elsevier Science B.V. All rights reserved.