Chemistry Stack Exchange is a question and answer site for scientists, academics, teachers, and students in the field of chemistry. It only takes a minute to sign up.
Sign up to join this community
In reverse-phase HPLC, Thiourea, Uracil, Nitromethane or $\ce{KNO3}$ are used as dead time markers because of their polarity and therefore weak interactions with the stationary phase. However, I could not find any substances typically used as dead time markers in normal-phase-applications. These would have to have small, non-polar molecules and a high boiling point (I know that's a little contradictory since nonpolar molecules only form weak intermolecular bonds).
Thanks in advance.
Interesting and complex question for normal phase LC! Couple of years ago, it was addressed in quite detail. Most of the practitioners have accepted 1,3,5-Tri-tert-butylbenzene for normal phase LC because it is extremely non-polar. It works with most normal phase mobile phases. Boiling point has nothing to do with NPLC.
However, if you really want true "void" volume of a column, pycnometry is the way to go. It is quite simple.
Determination of void volume in normal phase liquid chromatography in the Journal of Chromatography A See paper here
