Explanatory notes
… that elements existing in nature in the monoisotopic state, e.g., beryllium 9, fluorine 19, aluminium 27, phosphorus 31, … isotopes of these same elements obtained artificially (e.g. Be 10, F 18, Al 29, P 32, Mn 54) are, however, to be … radioactive compounds, or with non‑radioactive materials (e.g., unprocessed irradiated targets and radioactive …