Title: substance content
Long Title: IUPAC Gold Book - substance content
DOI: 10.1351/goldbook.S06073
Status: current

Definition
Amount-of-substance of a component divided by the mass of the system.

Notes
1) The term component is recommended for clinical chemistry, ISO uses 'substance'.
2) The term system is recommended for clinical chemistry, ISO uses mixture.
3) Use of the term level as a synonym for content is deprecated.
4) In describing a quantity, 'content' must be clearly differentiated from concentration.

Related Terms
- component: https://goldbook.iupac.org//terms/view/C01209
- concentration: https://goldbook.iupac.org//terms/view/C01222
- content: https://goldbook.iupac.org//terms/view/C01296
- mixture: https://goldbook.iupac.org//terms/view/M03949
- system: https://goldbook.iupac.org//terms/view/S06234

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)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/S06073/html
- json: https://goldbook.iupac.org/terms/view/S06073/json
- xml: https://goldbook.iupac.org/terms/view/S06073/xml

Citation: Citation: 'substance content' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.S06073
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Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.
Accessed: 2026-04-27T15:59:38+00:00