(Vd). The volume outside of the column packing itself. The interstitial volume (intraparticle volume + interparticle volume) plus extra column volume (contributed by injector, detector, connecting tubing, and endfittings) all combine to create the dead volume. This volume can be determined by injecting an inert compound (i.e.. a compound that does not interact with the column packing). Also abbreviated V0 or Vm.