Liquid Chromatography Detectors - Dispersion in Detector Sensors > Dispersion in Connecting Tubes > Page 4

Figure 2. Band Dispersion Resulting from Newtonian Flow

The dispersion in open tubes was examined by Golay (3) and Atwood and Golay (4) and experimentally by Scott and Kucera (5) and Lochmuller and Sumner (6). The variance per unit length of an open tube (H) according to Golay is given  by

 

where (Dm) is the diffusivity of the solute in the mobile phase,
(u) is the linear velocity of the mobile phase,
and (r) is the radius of the tube.

At relatively high velocities (i.e., at velocities much greater than the optimum velocity of the tube, which will usually be true for all connecting tubes)

Furthermore,                       

                    where (Q) is the flow rate through the tube.