Bio-Rad Bio-Gel P Polyacrylamide Gel - Manual (Page 11)

17
Section 8
Flow Rate Determination
Gel filtration is a diffusion controlled process: the efficiency of
resolution depends on flow rate and gel bead size uniformity. Highest
resolution is obtained when the flow rate is maintained in the range
of 2-10 cm/hr.** For a linear flow rate of 5 cm/hr, corresponding
column flow rates are obtained by multiplying by the column cross
sectional area:
Table 3. Flow Rate Determination
Recommended
Linear Flow Rate*
Column Cross Sectional Column Flow
cm/hr** Diameter Area (cm 2 ) Rate ml/hr
5 0.7 0.385 1.9
5 1.0 0.785 3.9
5 1.5 1.77 8.9
5 2.5 4.91 25
5 5.0 19.6 98
* In a 1.5 x 70 cm column. Flow rates will decrease with increasing
column length.
** ml/hr/cm 2 (cross sectional area) = cm 3 /hr/cm 2 = cm/hr
16
Increases in column diameter (cross sectional area) dramatically
increase throughput and flow rate (ml/hr). Maximum resolution is
achieved with the smallest bead diameter ranges (extra fine or fine
sizes). The highest flow rates are obtained with the medium sized
beads. The flow rate and resolution desired for the application, as
well as exclusion limit and fractionation range, should be considered
when selecting the appropriate gel filtration matrix.
Econo-Column ® glass chromatography columns are ideally suited
for use with Bio-Gel gel filtration media. The standard Econo-Column
chromatography columns come in six diameters, ranging from
0.5 to 5.0 cm, with lengths from 4 to 170 cm. These columns are
autoclavable and possess a bed support which can retain particles
greater than 20 µm. Note that some extra fine bead sizes for Bio-Gel
P gel are not compatible with Econo-Column chromatography
columns. For Econo-Column column and accessory ordering infor-
mation, consult the Bio-Rad catalog.
LIT174B 10/13/98 9:26 AM Page 16