28.02.2013 Views

Handbook of Size Exclusion Chromatography and Related ...

Handbook of Size Exclusion Chromatography and Related ...

Handbook of Size Exclusion Chromatography and Related ...

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Figure 10 Aggregation <strong>of</strong> a solution <strong>of</strong> protein-coated gold nanospheres after an<br />

antibody specific to the protein was introduced into the solution. (WF Reed <strong>and</strong> T Nguyen,<br />

unpublished results.)<br />

(forexample,timereleaseencapsulation)averyslowdissolutionisneeded.There<br />

havebeenanumber<strong>of</strong>experimental<strong>and</strong>theoreticalstudies<strong>of</strong>dissolution(59–62).<br />

The basic detector train used in the foregoing systems is readily used for<br />

dissolution monitoring. Normally,the sample to be dissolved is placed in avessel<br />

in atemperature-controlled bath, <strong>and</strong> aperistaltic pump is used to recirculate<br />

solution in the dissolution vessel through the detectors <strong>and</strong> back to the vessel.<br />

Usually,in-linefilters<strong>of</strong>achosenporesizeareusedtoensurethatnomacroscopic<br />

particles are pumped through the detectors.<br />

In some cases, in-line filters can affect the dissolution behavior if microaggregates<br />

or microgels are present during dissolution. An example <strong>of</strong> this latter<br />

caseisgiveninFig.11,whichshowsthedissolutionbehavior<strong>of</strong>apolyelectrolyte,<br />

sodiumpolystyrenesulfonate(PSS)inpurewater<strong>and</strong>alsoinwaterwitha100mM<br />

concentration<strong>of</strong>NaCl,withseveraldifferentin-linefilterporesizes(adaptedfrom<br />

Ref. 7). The inset shows the refractometer response, which measures the<br />

concentration <strong>of</strong> polymer dissolved in the solvent at each instant. There is very<br />

little differencebetweenthewaythePSSdissolvesinpurewater <strong>and</strong>insaltwater,<br />

© 2004 by Marcel Dekker, Inc.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!