Bio-Rad Prepacked Gravity Flow Columns for Ion Exchange - Manual (Page 6)

The ion exchange capacity, usually
expressed as meq/ml of resin, is equivalent to
the number of ion exchange sites per unit vol-
ume of resin. The following examples shows
the calculated volume of 1 N sodium hydrox-
ide that would be required to convert the 2 ml
of resin in a prefilled AG 50W-X8 (H+) Poly-
Prep column from the hydrogen form to the
sodium form. In general, it is recommended to
use only 70-80% of the theoretical capacity of
an ion exchange resin.
1 N = 1 equivalent/liter = 1 milliequivalent/milli-
liter (1 meq/ml)
AG 50W-X8 ion exchange capacity = 1.7 meq
1.7 meq/X ml = 1 N
1.7 meq/1 N = X ml
X = 1.7 ml
Therefore, 1.7 mls of 1 N NaOH required
to convert the AG 50W-X8 resin to the sodium
form.
Section 5
Flow Rate Characteristics
The flow rate of an ion exchange resin is
primarily determined by the particle size of the
resin. Using gravity flow, the expected flow
rate for 100-200 mesh resin in prefilled Poly-
Prep columns is approximately 4-6 ml/minute.
The flow rate for 200-400 mesh resin is
approximately 1.5 ml/minute.
Bio-Rex 70 resin has slower flow rate than
AG or Chelex resins. Bio-Rex 70 100-200 mesh
resin flows at approximately 1.0 ml/minute.
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