Investigations into chromium speciation by electrospray mass spectrometry

Chromium is an element whose toxicity is oxidation state dependent. Chromium(VI) is considered toxic to humans whereas CrIII is considered to be an essential nutrient. It therefore becomes important to be able to distinguish between the two oxidation states in solution. In this study it is shown that electrospray mass spectrometry (ESMS) has the potential to provide useful information on chromium species in solution samples. The various solution forms of both oxidation states may be observed directly and are presented. In addition, other more uncommon species of both oxidation states such as polymeric CrIII and the polyanion trichromate are discussed. Finally, the ability of ESMS to monitor other aspects of the solution chemistry of both chromium oxidation states is explored.