Malvern Zetasizer Nano Series, Руководство пользователя

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Introduction
Before filling the cell or cuvette that will be used in the measurement, the sample
will need to be prepared. To ensure reliable and accurate measurements proper
sample preparation is extremely important.
Preparation of the sample for the different measurement types will involve
specific preparation techniques. For each measurement type follow the guidelines
described.
Preparing the sample - Size
Consideration must be given to the physical properties of the sample such as its
particle size and sample concentration. This section outlines the basic
considerations for sample preparation.
Sample concentration
Each type of sample material has its own ideal range of sample concentration for
optimal measurements.
.
If the sample concentration is too low, there may not be enough light scat-
tered to make a measurement. This is unlikely to occur with the Zetasizer
except in extreme circumstances.
.
If the sample is too concentrated, then light scattered by one particle will it-
self be scattered by another (this is known as multiple scattering).
.
The upper limit of the concentration is also governed by the point at which
the concentration no longer allows the sample to freely diffuse, due to par-
ticle interactions.
An important factor in determining the maximum concentration the sample can
be measured at, is the size of the particles.
The table below can be used as an approximate guide to determine the maximum
and minimum concentrations for different sizes of particles. The figures given are
approximate values for samples with a density near to 1g/cm
3
, and where the
particles have a reasonable difference in refractive index to that of the dispersant,
e.g. a refractive index of 1.38 against water which has a refractive index of 1.33.
C H A P T E R 6
Z e t a s i z e r N a n o S e r i e s
P a g e 6 . 1