Particulate Systems NanoPlus, Operator'S Manual, Page: 223 / 252

NanoPlus Operator’s Manual Molecular Weight Analysis
Mar 2014 E-7
The NNLS (Non-Negative Least-Squares) Method
This is a least-squares algorithm which solves the matrix so that only positive values for A
i
’s are
obtained (in the Marquardt algorithm, negative values of A
i
may be obtained but the values are set
to ’0’ when this happens). Distributions obtained by this method tend to have narrow and
separated peaks.
Molecular Weight Analysis
The Molecular Weight (MW) analysis is performed for all types of particle size distributions. In
the Cumulants analysis, the average diameter is converted into MW. The MW analysis requires
that you enter two sample-dependent parameters,

and

, in order to calculate MW. The
transformation equation for mean molecular weight is as follows:
(9)
where D is the diffusion coefficient as defined in Equation (5).
MW

D
----
 
 
1

---
=