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Handbook of Size Exclusion Chromatography and Related ...

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Figure 11 Molecular weight distributions <strong>of</strong> quaternized polyvinyl pyrrolidone–<br />

dimethylaminoethyl methacrylate copolymers. (From Ref. 5.)<br />

5 SEC/MALLS OF PVP<br />

SEC/MALLS has been found very useful in characterizing polymers including<br />

PVP in this laboratory in recent years. For example, excellent overlap <strong>of</strong> absolute<br />

Mw versus retention volume plot for all grades <strong>of</strong> PVP demonstrate similarity<br />

in branching among all commercial grades, despite different manufacturing<br />

processes (14).<br />

6 CONCLUSIONS<br />

Successful SEC <strong>of</strong> PVP- <strong>and</strong> VP-based copolymers in both aqueous <strong>and</strong><br />

nonaqueous systems using commercially available columns has been reported in<br />

the literature. For PVP, separations based on hydrodynamic volume <strong>and</strong> universal<br />

calibration were also reported for both aqueous <strong>and</strong> nonaqueous SEC systems. In<br />

general, the aqueous SEC system (modified with methanol to eliminate polymer–<br />

column interactions) provides better separation than the nonaqueous SEC system,<br />

especially at the low-molecular-weight end. Therefore, aqueous SEC systems are<br />

preferred for PVP- <strong>and</strong> VP-based copolymers in general, as long as the aqueous<br />

system is applicable.<br />

For PVP, the optimized SEC system is the Shodex linear column KB-80M<br />

with 20:80 water–methanol (vol/vol) <strong>and</strong> 0.1 M lithium nitrate. For low- to<br />

medium-molecular-weight nonionic copolymers, such as PVP/VA, the optimized<br />

SEC system is a Shodex linear column KB-80M plus a low-molecular-weight<br />

Shodex KB-802 column <strong>and</strong> a mobile phase <strong>of</strong> 50:50 water–methanol (vol/vol)<br />

© 2004 by Marcel Dekker, Inc.

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