Particulate Systems NanoPlus, Руководство оператора, Страница: 191 / 252

NanoPlus Operator’s Manual Appendix C
Mar 2014 C-3
1. Obtain two or more (preferably monodisperse) samples of the same type with known
molecular weight values. These samples are going to be used as the “standards.” The
molecular weight range of these standards should be wider than, or similar to, the range of the
unknown samples.
2. Prepare solutions (or suspensions) of these standards using the same solvent and at the same
temperature that are to be used for the unknown samples.
3. Select Yes to Molecular Weight Calculation in the Analysis Parameters panel of the Size
SOP Designer . Enter alpha = 1 and beta = 1 .
4. Make good measurements of the standard samples and use the Cumulants analysis to obtain
the molecular weight. The obtained values are called the
apparent molecular weight , Mw.app.
5. Plot Log(M
w
) versus Log(Mw.app) for all standards and do a linear least-square fitting.
6. The

and

values can then be obtained from the following equations:
(2)
(3)
The above procedure is based on Equation (1). In Equation (1), if

= 1 and

= 1, then Mw.app =
1/DT.
When plotting in the logarithmic scale, Log(M
w
)= 1/

Log(

)-1/

Log(Mw.app). Therefore,

Slope = -1/

; and Intercept = 1/

Log(

).
References
Listed below are references for Alpha and Beta values.
1. Kramer O. and Frederick, JE., Macromolecules 4:613, 1971.
2. Poddubnyi IY, Podalinski AV, and Grechanovskii VA; Vysokomolekul Soedin 8:1556, 1966.
3. Brandrup J., Immergut EH., Grylke EA., Polymer Handboo k, fourth edition, Wiley & Sons,
Inc. 1999.

10
intercept/slope –
 
=

1
slope
-------------- =