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Handbook of Size Exclusion Chromatography and Related ...

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Another commercially available MW detector is a Multi Angle Laser Light<br />

Scattering (MALLS) photometer. It should be noted that a good chromatographic<br />

system is required for obtaining a meaningful MW <strong>and</strong> MWD, even if a MW<br />

detector (LALLS or MALLS) is used. In other words, the MW detector cannot<br />

solve chromatographic problems.<br />

3.2.3 Intrinsic Viscosity Determination<br />

The intrinsic viscosity <strong>and</strong> Mark–Houwink constants <strong>of</strong> st<strong>and</strong>ards can be<br />

determined from a static capillary viscometer or an on-line viscometer detector<br />

in an SEC system. If the intrinsic viscosity is to be used for constructing a<br />

universal calibration curve, it is important to use identical conditions in<br />

performing the SEC analysis <strong>and</strong> the intrinsic viscosity measurement. A Mark–<br />

Houwink plot for five PAM st<strong>and</strong>ards <strong>and</strong> one PAA st<strong>and</strong>ard is shown in Fig. 4.<br />

The intrinsic viscosity <strong>of</strong> PAM may decrease with time <strong>and</strong> becomes constant<br />

after about one week. It is recommended that the PAM solution be analyzed<br />

while still fresh.<br />

Figure 4 Mark–Houwink plot <strong>of</strong> five polyacrylamides <strong>and</strong> one polyacrylic acid.<br />

© 2004 by Marcel Dekker, Inc.

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