Bio-Rad ENrich™ High-Resolution Size Exclusion Columns - Manual (Page 11)

ENrich SEC Instruction Manual 7
3.3 Column Cleaning
Careful preparation (especially filtration) of the sample and the
buffers will maintain the column’s performance and extend
its lifetime. Normally, washing with a few CV of running buffer
with an ionic strength of at least 100 mM NaCl will remove
most contaminants. However, if there is a decrease in column
performance (that is, increasing backpressures or a drop in
resolution), then steps 1 and 2 of the cleaning protocol described
below should be used.
Always reverse the flow during this procedure so any substances
that may be trapped at the top of the column are quickly removed.
During this operation do not exceed more than 50% of the
recommended maximum flow rate (see Table 1). Ensure that the
backpressure stays below the maximum operating pressure.
1. Wash with 2 x 1 ml injections of 2.0 M NaCl followed by 1 CV
of buffer.
2. Wash with 2 x 1 ml injections of 1.0 M NaOH followed by 2 CV
of buffer.
If the column performance has still not returned, the additional
steps below can be followed:
3. Wash with 2 x 1 ml injections of 50% acetic acid followed by
2 CV of buffer.
4. If lipid contamination is suspected, first wash with at least
1 CV of deionized water. Then wash with 1 CV of 70% ethanol
followed by 2 CV of water. The flow rate may need to be
slowed significantly during the 70% ethanol wash.
Before use, re-equilibrate with at least 2 CV of equilibration buffer.
3.4 Frit Replacement
The top frit may need to be replaced after extensive column use
or if increasing backpressures are noticed. Always try to clean the
column in the reverse direction (as described in section 3.3) before
replacing the frit. A frit kit containing a frit removal tool, 2 O-rings,
and 2 frits is available.
Figure 2 shows a column diagram to assist in the replacement of
the top frit.