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Handbook of Size Exclusion Chromatography and Related ...

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Another detector recently applied in SEC is the evaporative light-scattering<br />

detector (ELSD). This detector is not used for oligomers as <strong>of</strong>ten as the RI <strong>and</strong> UV<br />

detectors are, because some very low MWoligomers may be evaporated. However,<br />

if it is used without the evaporation effect, the nonlinear sensitivity effect should<br />

he considered. Figure 9 shows that the sensitivity <strong>of</strong> this detector is lower at lower<br />

concentration ranges (9), which happen to be around the range for a typical LC<br />

or SEC analysis. Because the concentrations at both ends <strong>of</strong> a peak are<br />

underestimated, the calculated polydispersity (Mw=Mn) will he smaller than the<br />

actual number.<br />

Figure 9 Plot <strong>of</strong> the detector response for p,p 0 -diaminodiphenylmethane solutions in the<br />

concentration range 1:5 10 5 to 1:5 10 4 g/cm 3 . From Ref. 9, copyright 1978<br />

American Chemical Society.<br />

© 2004 by Marcel Dekker, Inc.

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