Term: substance fraction, \(x\)
https://doi.org/10.1351/goldbook.S06075

Definition:
Ratio of the amount-of-substance of the component to the total amount-of-substance in the system containing the component.

Notes:
0) The term substance fraction is recommended for clinical chemistry, IUPAC also uses @A00296@ and @A00296@.
1) For clinical chemistry the term @C01209@ is recommended, ISO uses 'substance'.
2) For clinical chemistry the term @S06234@ is recommended, ISO uses @M03949@.

Related Terms:
1) amount fraction <em>x</em> (<em>y</em> for gaseous mixtures) (http://doi.org/10.1351/goldbook.A00296).
2) component (http://doi.org/10.1351/goldbook.C01209).
3) system (http://doi.org/10.1351/goldbook.S06234).
4) mixture (http://doi.org/10.1351/goldbook.M03949).

Source: PAC, 1996, 68, 957. 'Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)' on page 994 (https://doi.org/10.1351/pac199668040957)

Citation: 'substance fraction, \(x\)' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.S06075

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