10
Downstream
thirty seven
Testing the packed column
Three packings were made according to the basic method
outlined above.
The following tests were run: column efficiency, asymmetry,
Van Deemter analysis, sample volume and pressure/flow rate.
Selected results are given below. More detailed information is
available in Application Note 11-0007-52 Scaled-up method
for packing MabSelect in large diameter Chromaflow columns.
Table 1 shows bed efficiency (expressed as plates/meter) and
asymmetry data for the three column packings and Table 2
the Van Deemter analysis from one of them.
The plate numbers were excellent and the asymmetry values
close to 1.0 in all cases. Van Deemter data, a measure of how
robust the bed is when flow rates are increased, were also
good. Bed efficiency decreased somewhat, i.e. the reduced
plate height values increased as fluid velocity increased from
20 to 80 cm/h, but asymmetry values were essentially
unchanged. This result was expected, as it follows theory. A
similar test with sample volume increasing from 1 to 7% gave
almost identical results, also as expected (data not shown).
The pressure/flow rate curve (Figure 2) shows normal
behavior without any sign of liquid gap formation.
Significantly, the pressure drop at 500 cm/h is below 1 bar,
which is much better than the acceptance criteria required.
Pressure-flow in packed bed
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
0
100
200
300
400
500
600
700
800
Velocity [cm/h]
Pressure [bar]
Further information
For further details, please ask for the MabSelect Data File
(Code no. 18-1149-94), the Chromaflow column Data File
(Code no. 18-1138-92) and Application Note Scaled-up method for
packing MabSelect in large diameter Chromaflow columns
(Code no. 11-0007-52).
See also Downstream 33 (Code no. 18-1150-32)
and Downstream 36 (Code no. 18-1171-05).
About Chromaflow columns
Chromaflow columns are a family of convenient to use, process-
scale columns, intended for GMP manufacture. A patented nozzle
in the top and bottom of the column allows packing, unpacking
and cleaning with the lid in place.
The standard range offers inner diameters from 400 mm to
2000 mm. All are pressure-rated for operation at 3 bar. In
addition, all Chromaflow columns with stainless steel bed
supports meet the criteria to pass the USP Class VI tests for
toxicity.
Chromaflow columns simplify chromatographic procedures. A
single operator can perform all column operations, thereby
reducing labor costs and increasing convenience. Packing with the
lid in place also allows packing parameters to be fixed and
standard operating procedures followed. Manual operation is
minimized, helping achieve reproducible packing and results.
Finally, because all column operations are performed in a `closed'
environment, overall safety and hygiene are improved.
Table 1. Packing flow rates and efficiency data tested at a fluid velocity
of 20 cm/h. These figures show that the method results in highly
efficient packed beds.
Pack no.
Packing
Plates/m
*
Reduced
Asymmetry
flow rate
plate
(l/min)
height, h
**
1
74
: 7180
1.56
: 1.08
: 5990
1.88
: 1.00
2
70
: 6050
1.86
: 1.04
: 5190
2.16
: 1.00
3
72
: 6100
1.84
: 1.05
: 5450
2.06
: 1.00
* Arrows indicate test direction, i.e. upward or downward flow.
** h = 1/(plates/meter x particle size).
Ratio of 1st half peak width to 2nd half peak width, at 10% peak height: should be as close as
possible to 1.
Table 2. Van Deemter test results at increasing flow velocities confirm
the robust nature of the packed bed.
Test velocity
Bed efficiency
Reduced plate
Asymmetry
(cm/h)
(Plates/m)
height, h*
20
5190
2.16
1.00
60
4350
2.58
1.01
80
3810
2.95
0.97
* Reduced plate height, h = 1/(plates/meter x particle size).
Conclusion
Packing MabSelect in a Chromaflow 600 column with the
described method (packing flow rate of 1500 cm/h ending
when the bed is 0.5 cm from the top net) is fast, simple and
successful. One person can perform the whole packing
procedure in less than 30 minutes, confirming that the
Chromaflow column design is both labor-saving and cost-
effective. Efficiency results were excellent and stability data
indicated that the packed bed would be robust and
reproducible in use.
Packing MabSelect in a large-scale Chromaflow column is
reliable, simple and fast operation. Commercial
manufacturers should be encouraged to consider this
combination when deciding how best to process their
monoclonal antibodies.
Fig. 2. Pressure/flow rate curve of the packed bed shows normal behavior.
The bed is stable and the pressure drop at 500 cm/h is below 1 bar.
