Malvern Zetasizer Nano Series, Руководство пользователя

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We can therefore stipulate that if the particle is small, Rayleigh scattering can be
assumed and the Rayleigh approximation used.
With the Zetasizer Nano series the applicable molecular measurement weight
range is from a few hundred g/mol to 500,000 for linear polymers, and over
20,000,000 for near spherical polymers and proteins.
The Debye plot
The intensity of scattered light that a particle produces is proportional to the
product of the weight-average molecular weight and the concentration of the
particle.
The Zetasizer Nano S and ZS measure the Intensity of scattered light
( K/CR
q
) of various concentrations ( C ) of sample at one angle; this is compared
with the scattering produced from a standard (i.e. Toluene).
The graphical representation of this is called a Debye plot and allows for the
determination of both the Absolute Molecular Weight and 2
nd
Virial Coefficient.
The Molecular weight ( Mwt ) is determined from the intercept point on the X
axis. i.e. K/CR
q
= 1/MWt in Daltons .
The 2
nd
Virial Coefficient ( A
2
) is determined from the gradient of the Debye
plot.
Each plot and molecular weight measurement is performed by doing several
individual measurements; from just the solvent used (a zero concentration
measurement), through sample preparations of various concentrations.
C H A P T E R 1 4 Z e t a s i z e r N a n o S e r i e s
P a g e 1 4 . 4
M A N 0 3 1 7
Intensity
Debye
ILL
6775