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Handbook of Size Exclusion Chromatography and Related ...

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Figure 2 A broad-MWD PAM st<strong>and</strong>ard obtained from five individual PAM samples.<br />

depend on the choice <strong>of</strong> the final process time. With the positive salt peak, a<br />

significant amount <strong>of</strong> area was eliminated in the MW <strong>and</strong> MWD determination.<br />

This results in a narrower polydispersity. With the negative salt peak, a small area<br />

<strong>of</strong> the salt peak was included in the MW <strong>and</strong> MWD determination. This results in a<br />

broader polydispersity.<br />

The RI, UV, LLAS, <strong>and</strong> viscometer detectors have been successfully<br />

used in this work. The FTIR detector has been applied to study protein by<br />

Remsen <strong>and</strong> Freeman (54). It is difficult to obtain a strong signal from the<br />

conductivity detector (Waters Model 430) because <strong>of</strong> the high-ionic-strength<br />

mobile phase.<br />

3.2 Characterization <strong>of</strong> Molecular Weight St<strong>and</strong>ards<br />

3.2.1 Static LALLS Experiment<br />

This experiment determines the absolute M w <strong>of</strong> a polymer in solution. It requires<br />

the specific refractive index increment [(dn/dc) T,l,m] (55–57) <strong>of</strong> the polymer<br />

© 2004 by Marcel Dekker, Inc.

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