recovery factor [obsolete]

in an extraction process
https://doi.org/10.1351/goldbook.R05207
The fraction or percentage (R%) of the total quantity of a substance extracted (usually into the organic solvent phase) under specified conditions. Specifically, $$R_{\text{A}}=\frac{Q_{\text{A}}}{\left(Q_{\text{A}}\right)^{'}}$$, where $$\left(Q_{\text{A}}\right)^{'}$$ and $$Q_{\text{A}}$$ are the original and final quantities of the substance A. This term is not recommended. @F02503@ should be used.
Sources:
Orange Book, 2nd ed., p. 90 [Terms] [Book]
PAC, 1993, 65, 2373. (Nomenclature for liquid-liquid distribution (solvent extraction) (IUPAC Recommendations 1993)) on page 2385 [Terms] [Paper]