Unsuitability of (12)C 60 as a standard of atomic weight.

A critical discussion is given of the suggestion by Dougherty et al. (J. Am. Soc. Mass Spectrom. 1994, 5, 120) that the (12)C60 molecule replace the (12)C atom as the primary standard of atomic mass. Adoption of the proposed standard would require that the unified atomic weight/mass scale, finally achieved with much difficulty in 1960, be abandoned without demonstrable benefit. Furthermore, the proposed standard has a molecular mass that is inherently ambiguous at a level that makes it unacceptable for that purpose.