Thermo Scientific gibco CTS Rotea User Manual page 63

Observation
Clumps
CTS ™ Rotea ™ Counterflow Centrifugation System Process Design User Guide
Possible cause
Clumps will behave like very
large particles in the CFC
Chamber and hence will be
concentrated at the tip.
Chapter 4 Protocol Building Blocks
Establish a fluidized bed
Recommended action
It is recommended that clumpy material be
drawn from a bag lying on its side or a vessel
where the lowest point is adjusted mid process
so rapidly settled clumps are not the first
material to be loaded. Mixing of the input bag
during loading can also help to prevent settling
™
of clumps. The Rotea instrument can be used
to separate good cells from these large clumps
by elutriating the good cells to an intermediate
bag, removing the clumps to a waste bag, such
as line E or F, then re-loading the clump free
cells for wash and recovery. This process should
be performed at relatively high flow rates to
minimize the potential for blockage of the tip
during recovery of the clumps.
Note:
·
Clumps often reflect DNA being released
from the disruption of cells damaged by
upstream processes such as thawing. The
clumps may not always be evident prior to
processing. Keeping the centrifuge speed as
low as practical is recommended for such
processes.
·
If clumps in the input material settle near to
™
the Rotea input line, they will be drawn into
in the CFC Chamber at the very beginning of
bed formation and accumulate at the tip of
the CFC Chamber. The accumulated clumps
can then disrupt the fluid flow, making it
difficult for the cell bed to form.
·
Accumulated clumps have the potential to
cause blockages of the Dip Tube. While they
can sometimes be cleared by cycling back
and forth in pause or recirculation at high flow
rates, some clumps, e.g. DNA, can be difficult
to remove. This can be especially challenging
when processing large batches containing
clumps in multiple bites.
·
The clumps will usually be recovered along
with the rest of the cells in the fluidized bed
and may be an undesirable impurity.
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