bound/free ratio

in immunoassay
initialism: B/F
https://doi.org/10.1351/goldbook.09667
Amount of analyte bound by a label divided by amount of unbound (free) analyte
Source:
PAC, 2018, 90, 1121. (Terminology of bioanalytical methods (IUPAC Recommendations 2018)) on page 1137 [Terms] [Paper]