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Handbook of Size Exclusion Chromatography and Related ...

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Figure 11 Light scattering from solutions <strong>of</strong> dissolving polyelectrolytes under different<br />

conditions; in pure water with different on-line membrane filter pore sizes, <strong>and</strong> in salt water<br />

(0.1 M NaCl) with a 0.45m filter. The initial sharp peaks in scattering are due to “bursts” <strong>of</strong><br />

micro-aggregates that appear upon dissolution in pure water, whose heights depend<br />

critically on filter pore size. The inset shows the actual concentration <strong>of</strong> polymer in solution,<br />

obtained from simultaneous RI measurements, which are insensitive to aggregates. The<br />

different conditions have little effect on the dissolution kinetics themselves. (From Ref. 7.)<br />

<strong>and</strong> the type <strong>of</strong> in-line filter size also has no appreciable effect. In dramatic<br />

contrast, however, is the TDSLS signal, which is proportional to the quantity cMw<br />

at the very low concentrations used in these experiments. Large scattering spikes<br />

are seen at the outset <strong>of</strong> the dissolution in pure water, being largest for the coarsest<br />

© 2004 by Marcel Dekker, Inc.

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