Millistak+HC AppGd_textC.qxd - Millipore

Scale-up
During the optimization process, tests
should be run at three separate scales,
and Millistak+ HC filters are available
in device sizes to match these steps.
Initial experiments can be run on
the two smaller Millistak+ HC filters.
Care should be taken to operate
in a constant-flux manner, recording
the pressure increase. If desired,
Millipore’s Pmax SM system can be
employed, to increase the efficiency
of interpreting the test data.
First, to determine the correct type
of Millistak+ HC filters to incorporate
into the process, screening with test
volumes of 100–1000 mL can be
performed with the Millistak+ HC Mini
Capsule (23 cm 2 ). To normalize for
variability in filter media and process
stream, multiple tests (at least three)
are recommended, with different
batches of test fluid.
The next step would be to process
5–25 L of solution through an Opticap
capsule filter with Millistak+ HC media
(650 cm 2 ). Again, testing multiple
devices with multiple process samples
will ensure that the sizing is as accurate
as possible.
When the process has been well
characterized, the process-scale
device can be tested, on volumes
greater than 50 L. Each processscale
16-inch 8-cell cartridge
provides 1.8 m 2 of filtration area.
Care should be taken to
simulate as closely as possible the
final process conditions. Since biological
process streams are very complex
mixtures, their properties could change
drastically if any process parameters
have been changed. If the temperature
of the fluid is not kept constant,
if the age of the fermentation is
changed or if it is stored overnight
under refrigeration, the solution may
change—precipitants may form,
proteins may denature, etc.—and
the sample will, consequently, no
longer be representative of the final
process fluid.
Millistak+ HC Filters Application Guide 19