saturation fraction, $$s_{\text{B}}$$

https://doi.org/10.1351/goldbook.S05476
Amount-of-substance of a component (solute) in a solution divided by the amount-of-substance of the component when it is saturating the system at constant temperature and pressure. Also referred to simply as @S05472@, for example oxygen @S05472@.
Source:
PAC, 1996, 68, 957. (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 991 [Terms] [Paper]