hold-up time

in chromatography
symbol: $t_{\rm{M}}$
https://doi.org/10.1351/goldbook.10038
Time required to elute a component which is not retained by the stationary phase.
Notes:
  1. The hold-up time includes any time that the component spends in the sample injector, the detector, and connectors.
  2. The hold-up time is related to the hold-up volume (\(V_{\rm{M}}\)) and flow rate (\(F_{\rm{c}}\)) by \(t_{\rm{M}} = V_{\rm{M}}⁄F_{\rm{c}}\) .
Source:
PAC, 2017, 90, 181. 'Terminology of separation methods (IUPAC Recommendations 2017)' on page 196 (https://doi.org/10.1515/pac-2017-0111)