Bio-Rad AG® MP-1M Anion Exchange Resins - Manual (Page 4)

exclusion limits in water for resins of various crosslink-
ages.
Table 1. Approximate Molecular Weight Exclusion
Limits for Ion Exchange Resins in Water
Percent Approximate MW Exclusion Limit
Crosslinking for Globular Molecules
2% 2,700
4% 1,400
8% 1,000
10% 800
12% 400
AG 2 resin is similar to AG 1 resin, but is slightly
less basic and slightly less resistant to oxidation due to
differences in the structure of the quaternary functional
group. It offers advantages in certain applications. For
example, it is capable of separating sugars, sugar alco-
hols, and glycosides using a step gradient and borate
buffers without isomerizing some sugars, as AG 1 resin
tends to do.
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AG 1 and AG 2 resins are strongly basic anion
exchangers with quaternary ammonium functional
groups attached to the styrene divinylbenzene copoly-
mer lattice. The amount of resin crosslinkage determines
the bead pore size. A resin with a lower percentage of
crosslinkage has a more open structure permeable to
higher molecular weight substances than a highly
crosslinked resin. It also has a lower physical resistance
to shrinking and swelling, so that it absorbs more water
and swells to a larger wet diameter than a highly
crosslinked resin of equivalent dry diameter. For exam-
ple, the lower crosslinked resins, particularly AG 1-X2
2% crosslinked resin, are useful for the sorption and
fractionation of relatively high molecular weight sub-
stances such as peptides, ribo- and deoxyribo-
nucleotides, and uranium. The higher crosslinked resins,
particularly AG 1-X8 8% crosslinked resin, are used for
sorption, exchange, and separation of low molecular
weight inorganic anions, and in applications such as
cyclic nucleotide assays and fractionation of organic
acids. Table 1 shows the approximate molecular weight
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LIT212C 6/17/98 12:25 PM Page 2