1H NMR investigations of the molecular nature of cobalt(II) ions in human saliva

► The speciation status of Co(II) ions in human saliva was studied by 1H NMR analysis. ► The prevalent salivary Co(II) complexes were lactato>formato ≈histidinato> succinato. ► Results reflect the salivary levels of such complexants and Keq values for their Co(II) complexes. ► Selected Co(II)-complexed biomolecules can serve as 'site-specific' OH radical scavengers. ► Results acquired are of significance regarding the bioavailability and toxicity of Co(II).