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Definition of Dead Volume.
Posted: Sun Aug 23, 2009 8:41 am
by chem007
Hello. I'm a new member here. I was just reading through some materials on HPLC and I noticed that the term "Dead Volume" comes up quite a lot. I have done some internet research and not all of them give you a consistent definition.
The way I understand it is, a dead volume "maximum liquid volume" that can fill up the packed column. Is that right?
Posted: Sun Aug 23, 2009 11:49 am
by virtu
"dead volume" of column - Void volume of column - Vo
"dead volume" of CS (chromatography system) or "dead volume" Vm=Vo+Vinj.(injector)+Vcap.(communications)+Vc(detector cell)
If Vo(column)>>[Vo(injector)+Vo(communications inj.-col.-det.)+Vo(detector cell)]: Vo=Vm (approx.)
“Void volume (Vo) (of column): The total volume of mobile phase in the column; the remainder of the column is taken up by packing material. This volume can be determined by injecting an unretained substance(if Vm=Vo). R.E. Majors and P.W. Carr LC•GC 19 (2001), p. 124.
Posted: Mon Aug 24, 2009 1:01 pm
by tom jupille
And, because many of us (myself included!) are somewhat sloppy about terminology, "void volume" is often used to refer to excess unswept volume (in a poorly assembled fitting, or at the head of a column where the bed has shrunk, for example). Those are usually evident from context.