Bio-Rad Chelex® 100 Resin - Manual (Page 7)

The resin volume of the sodium form in various
solvents is (the resin exhibits appreciable capacity in
organic solvents):
water 1.00, acetone 0.47, methanol 0.70, ethanol
0.45, isopropanol 0.48, ethyl acetate 0.96.
Calculating Capacity
A step-by-step method is used for determining the
approximate amount of resin needed to remove heavy
metal ions from aqueous systems.
1. Determine total volume of solution to be treated
to remove heavy metals.
Example: 10 liters
2. Calculate the average molecular weight of metals
to be exchanged.
Example: Using Cu +2 , Cd +2 , Cr +3 ;
227.9/3=76 grams/mol
= average MW
∑ MW
n
11
volumes 1 N NaOH, 5 bed volumes water rinse. In
some cases, especially with strongly complexed met-
als such as iron, complete regeneration can be accom-
plished only by using the two-step regeneration
procedure. Single-step conversions are adequate when
going from weakly held to strongly held ions. Thus
the calcium form is prepared from the sodium form
using 2 bed volumes of 2 N calcium chloride.
Chelex 100 resin undergoes volume changes
when its ionic form is altered or the external medium
is changed. The resin swells 100% in going from the
hydrogen to a monovalent salt form. Therefore, nor-
mal precautions, such as wrapping columns with tape,
should be taken to protect against glass breakage.
Using the resin in the calcium form is a method that
has been used to prevent shrinkage upon elution. The
resin volume in water of different ionic forms is:
Na + 1.00; H + 0.45; Cu +2 0.60; Fe +2 0.45; Zn +2 0.55;
Ca +2 0.53; K + 1.06; Li + 0.98; Ag + 0.70; Cr +3 0.53.
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LIT200B 6/17/98 11:49 AM Page 10