Gas Chromatography - Gas Supplies > Flow Programmers > Page 9

Flow Programmers

Flow programming is a procedure where the mobile phase flow-rate is increased during chromatographic development. If the mobile phase is compressible the relationship between retention volume, flow rate and inlet pressure is given by,

(1)

Where (Vr) is the true retention volume of the solute,
(Vr(0)) is the retention volume measured at the outlet.
and (g) is the inlet/outlet pressure ratio

(for the derivation of this equation see The Thermodynamics of Chromatography)

Thus,

Now, from The Thermodynamics of Chromatography
where (e) is a constant

Thus, (2)

If (g) is large compared with unity, Then