Bio-Rad AG® MP-50 Cation Exchange Resins - Manual (Page 7)

Table 5. Techniques for AG Resin Conversion
Bio-Rex ®
AG 50 resin MSZ 50 resin
Conversion H + ➝ Na + H + ➝ pyridinium
from ➝ to
Reagent used
1 M NaOH 1 M pyridine
(wash with H
2
O
before pyridine)
Volumes of sol’n/ 2 2
vol. of resin
Flow rate
(2) 2 1
ml/min/cm 2 of bed
Type of exchange (1) N N
Test for completeness pH 9 (3) —
of conversion
Rinse: vol. DI water/
4 —
vol. resin
Test for completion
pH<9 —
of rinsing
1. N = Neutralization
2. For 50-100 or finer mesh resin. For 20-50 mesh, about 1 ⁄ 5 the flow
rate is recommended.
3. Test for pH 4.8 – pH paper or methyl orange (red pH 1, yellow
pH 4.8). Test for pH 9 – pH paper or thymolphthalein (blue pH 10,
colorless at pH 9).
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remember that the resin may shrink, or it may swell as
much as 100%, depending on the conversion.
Conversions to ionic forms not listed in Table 5 can
be achieved using the information supplied in Table 3,
which lists relative selectivities of various counterions
for AG 50 resin. To convert a resin to an ionic form with
a higher selectivity, wash the resin with 2-3 bed volumes
of a 1 M solution of the desired counterion. For
conversion to an ionic form with a lower relative
selectivity for the resin, the necessary volume of
counterion solution will depend on the difference in
selectivity. As a general rule, use 1 bed volume of 1 M
counterion solution for each unit difference in relative
selectivity. For example, converting AG 50W-X8 resin
from the K
+ form (relative selectivity 2.5) to the H + form
(relative selectivity 1.0) would require 2-3 bed volumes
of 1 M HCl. The conversion is complete when all the K
+
ions are displaced by the H + ions.
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LIT203B 6/17/98 12:00 PM Page 8