Singly labelled

{
  "id": "MLC-T-CHM-010909",
  "term": "Singly labelled",
  "field": "Chemistry",
  "definition": "Describing a chemical compound in which only one specific atom of a particular element has been replaced by an isotope of that element. The isotopic substitution occurs at a single, defined position within the molecule. This contrasts with multiply labelled compounds, where more than one atom or position is isotopically modified.",
  "subject": "Inorganic Chemistry",
  "see_also": [
    "isotopically modified",
    "isotopically substituted",
    "specifically labelled"
  ],
  "references": [
    "Blue Book, p. 515 (https://www.acdlabs.com/iupac/nomenclature/)",
    "PAC, 1981, 53, 1887. 'Nomenclature of inorganic chemistry: II.1 - Isotopically modified compounds' on page 1892 (https://doi.org/10.1351/pac198153101887)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/singly-labelled/"
}