mass spectrometry role adduct ion role adduct ion role K. K. Murray, R. K. Boyd, M. N. Eberlin, G. J. Langley, L. Li and Y. Naito, Pure Appl. Chem., 2013, 85, 1515-1609 For example, a Na+ adduct of a molecule (M) that is represented as [M + Na]+. adduct role Adduct ion role is the role of an ion formed by the interaction of a precursor ion with one or more atoms or molecules to form an ion containing all the constituent atoms of the precursor ion as well as the additional atoms from the associated atoms or molecules. [IUPAC] adduct ion adduct