Biomedical Engineering Reference
In-Depth Information
is an important quantity. Because it is easy to measure, the flow
rate is often given as volumetric flow rate V with the dimension
milliters per minute. But this quantity depends on the diameter
of the column; therefore, it would be better to give the linear flow
rate L in centimeters per hour, which eliminates the cross-section
of the columns:
V
240
π
·
d
2
·
=
L
h
−1
); V: volumetric flow rate (ml
min
−1
);
L: linear flow rate (cm
·
·
d: inner diameter of the column (cm).
When mechanically stable gels are used, the linear flow rate L
is proportional to the applied pressure (Darcy's law):
·
∆
C
h
=
L
H
L: linear flow rate in centimeters per hour; C: constant of propor-
tionality dependent on the properties of the bed material and the
applied buffer;
∆
h: hydrostatic pressure in centimeters (cf. Fig. 3.3);
H: bed height in centimeters.
For Sephadex the following values of proportionality constant
C are given in Table 3.1.
Fig. 3.3.
Column chromatography. Principle of column filling and variants of chromatographic
run (for descriptions see text)
