Bio-Rad Bio-Rex® 70 Cation Exchange Resins - Manual (Page 7)

with 5 grams of resin for 100 ml of sample, and then
optimize the volumes after obtaining the results.
2. Insure that the resin is in the proper ionic form,
which will allow the sample ions to be exchanged
onto the resin. If conversion of the resin to another
ionic form is necessary, use the guidelines described
in Section 4 for resin conversion.
3. Prepare the initial buffer, so that the pH and ionic
concentration will allow the sample ions to be
exchanged on to the column. For unknown solutions,
use deionized water.
4. Slurry and pour the resin into the column. Resin
should be equilibrated according to the instructions
outlined above. Poorly equilibrated resin will not
give reproducible results.
5. Allow excess buffer to pass through the column,
leaving enough buffer to just cover the top of the
resin bed.
6. Apply the sample dropwise to the top of the column
without disturbing the resin bed. Drain the sample into
the top of the bed and apply several small portions of
starting eluant, being very careful to rinse down the
sides of the column and to avoid stirring up the bed.
Drain each portion to the level of the resin bed before
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5.1 Batch Method
The batch method is performed by adding the resin
directly to the sample and stirring. The resin should be in
correct ionic form and equilibrated prior to beginning.
1. Weigh out about 5 grams of resin for every 100 ml of
sample. For larger scale applications or when an
exact amount of resin is needed, calculate the resin
volume based on the resin capacity.
2. Add resin to the sample and stir or shake (gently) for
1 hour.
3. Filter or decant the sample from the resin.
5.2 Column Method
The column method involves pouring a column of
resin and passing the sample through to achieve the
separation. Particle size will determine the flow rate,
which will affect the separation. The resin should be in
the correct ionic form and equilibrated prior to adding
the sample.
1. Calculate the amount of resin required based on the
expected resin capacity and sample concentration. If
the sample ionic concentration is unknown, begin
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