Bio-Rad AG® MP-50 Cation Exchange Resins - Manual (Page 4)

Fig. 1. Removal of (A) ethidium bromide and (B) propidium
iodide by AG 50W-X8 cation exchange resin.
R is the resin matrix;
SO
3
- is the functional group covalently attached to the resin.
Section 3
Instructions for Use
For removing ethidium and propidium salts from
plasmids, the resin is slurried in a pH 8.0 Tris buffer and
poured into a column. The sample pH is adjusted to pH
8.0. Thus the DNA will be anionic, and ethidium and
propidium will be cationic. When the sample is added to
the column, the ethidium and propidium are exchanged
for sodium ions on the resin. The pure plasmid
preparations pass through the column immediately (in
the void volume) and the fluorescent dyes are bound to
R SO 3
-
NH 2
H 2 N
Br
N +
CH 2 CH 3
R
NH 2
H 2 N
ZI-
N +
CH 2 CH 2 CH 2 N 1 —CH 2 CH 3
CH 2 CH 3
CH 3
SO 3
-
3
Section 2
Description
AG 50W-X8 cation exchange resin is the backbone
resin of the Molecular Biology Grade AG 50W-X8
resin. AG 50W-X8 resin is a strong cation exchanger
with sulfonic acid functional groups attached to a styrene
divinylbenzene copolymer lattice. The Molecular
Biology Grade resin is provided in the sodium form. It
has been specially equilibrated in Tris buffer at pH 8.0.
The resin is capable of exchanging cations of salts, and
of ampholytes on the acidic side of their pI. This resin
can be used to extract basic compounds from a solution
with a pH at least 1 unit lower than the pK
a
of the
analyte. The analytes are then eluted with a neutral or
basic pH solution.
2
A B
LIT304B 9/3/98 6:51 AM Page 2