multilayer coil

in counter-current chromatography
https://doi.org/10.1351/goldbook.09946

Separation column used for high-speed counter-current chromatography.

Notes:
  1. The multilayer coil is prepared from a long piece of polytetrafluoroethylene (PTFE) tubing by coaxially winding it around a spool-shaped holder, making multiple coiled layers.
  2. Usually, three different inner diameter sizes of tubing are used: ca. \(\pu{1 mm}\) for analytical, \(\pu{1.6 mm}\) for semipreparative, and \(\pu{2.6 mm}\) for preparative separations. It provides efficient mixing of the two phases and a high retention of the stationary phase under a high flow rate of the mobile phase.
Source:
PAC, 2017, 90, 181. 'Terminology of separation methods (IUPAC Recommendations 2017)' on page 204 (https://doi.org/10.1515/pac-2017-0111)