Title: fluorescence polarisation
Long Title: IUPAC Gold Book - fluorescence polarisation
DOI: 10.1351/goldbook.14135
Status: current

Definition
Dimensionless value determined from the fluorescence intensities (\(I\)) measured parallel (\(I_{\Vert}\)) and perpendicular (\(I_{\perp}\)) to the excitation plane: \[p = \frac{I_{\Vert} - I_{\perp}}{I_{\Vert} + I_{\perp}}\]

Note
Fluorescence anisotropy (\(r\)) differs only in normalization and is determined from \[r = (I_{\Vert} - I_{\perp})/(I_{\Vert} + 2I_{\perp})\]

Related Term
- fluorescence polarization assay: https://goldbook.iupac.org//terms/view/14136

Source
- PAC, 2011, 83, 1129. 'Glossary of terms used in biomolecular screening (IUPAC Recommendations 2011)' on page 1141 (https://doi.org/10.1351/PAC-REC-09-05-03)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/14135/html
- json: https://goldbook.iupac.org/terms/view/14135/json
- xml: https://goldbook.iupac.org/terms/view/14135/xml

Citation: Citation: 'fluorescence polarisation' 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.14135
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Accessed: 2026-06-28T12:30:20+00:00