09937 IUPAC Gold Book - hyperlayer focusing field-flow fractionation 10.1351/goldbook.09937 09937 current initialism: HyFFF synonyms: hyperlayer field-flow fractionation mode, lift-hyperlayer field-flow fractionation mode 1 Mechanism of field-flow fractionation of particles greater than \(\pu{1 \upmu m}\) in diameter relying on hydrodynamic lift forces near the channel wall to move particles into faster flowing streams. HyFFF is a preferred alternative to steric field-flow fractionation. The retention of particles larger than \(\pu{1 \upmu m}\) typically increases with flow rate. Particles are driven away from the wall by a hydrody-namic lift force and elevated into faster flow streams. The particles form thin layers at an equilibrium position, where the external field is balanced by the opposing hydrodynamic lift force, as compared to steric mode, where the thin layer of particles is adjacent to the accumulation wall. Due to the large size of the particles, Brownian diffusion away from the accumulation wall is assumed to be negligible in this mode. field-flow fractionation https://goldbook.iupac.org//terms/view/09934 steric field-flow fractionation https://goldbook.iupac.org//terms/view/09940 PAC, 2017, 90, 181. 'Terminology of separation methods (IUPAC Recommendations 2017)' on page 221 (https://doi.org/10.1515/pac-2017-0111) https://goldbook.iupac.org/terms/view/09937/html https://goldbook.iupac.org/terms/view/09937/json https://goldbook.iupac.org/terms/view/09937/plain Citation: 'hyperlayer focusing field-flow fractionation' 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.09937 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . 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. 2026-07-26T19:28:17+00:00