Handbook of Size Exclusion Chromatography and Related ...

Figure 8 Effect of band broadening for a polymer with polydispersity 2 on the measured
moments of the molecular weight distribution by viscometry and universal calibration,
where D2 is the slope of log molecular weight and elution volume and sB is the peak
variance caused by band broadening. (From Ref. 37.)
the effect of band broadening means that the molecular weight profile no longer has
a one-to-one correspondence to the intrinsic viscosity elution profile, from which
the universal calibration curve is determined. The corrected intrinsic viscosity,
without band broadening, can be calculated using the method of Hamielec (43):
[h](V) ¼
F(V )
F(V E2s2 2
e1=2(E2s) [h](V) exp
)
(25)
where [h](V) is the corrected intrinsic viscosity at each elution volume V and
[h](V) exp is the experimentally determined intrinsic viscosity at each elution
volume, F is the concentration chromatogram, s is the Gaussian band-broadening
parameter, and E2 is the slope of the intrinsic viscosity calibration curve
[h](V) ¼ E1e E2V
(26)
From this, the true molecular weight calibration curve can be determined and can
then be used to calculate the correct MWD.
© 2004 by Marcel Dekker, Inc.