Malvern Zetasizer Nano Series, Руководство пользователя

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is called the stationary layer and is where the two laser beams cross; the zeta
potential measured is therefore free of electroosmotic errors.
Avoiding Electroosmosis
The stationary layer technique described above has been in use for many years.
Because of the effect of electroosmosis the measurement can only be performed
at specific point within the cell. If is was possible to remove electroosmosis
altogether then it would be possible to performed the measurement on the
particles at
any point in the cell and obtain the true mobility.
This is now possible with the Zetasizer Nano series of instruments. With a
combination of Laser Doppler Velocimetry and
P hase A nalysis L ight S cattering
( PALS ) this can now be achieved in Malvern’s patented M3-PALS technique.
Implementation of M3-PALS enables even samples of very low mobility to be
analysed and their mobility distributions calculated.
The M3-PALS technique
To perform measurements at any point within a cell and obtain the
electrophoretic mobility Malvern has developed its patented
M3-PALS
technique. This is a combination of Malvern’s improved laser doppler
velocimetry method - the
M3 measurement technique, and the application of
PALS ( P hase A nalysis L ight S cattering).
The M3 technique
As discussed traditional electrophoretic measurements are performed by
measurement of particles at the stationary layer, a precise position near the cell
walls. With M3 the measurement can be performed anywhere in the cell, though
with the Zetasizer Nano series it is performed in the centre of the cell.
M3 consists of both S low F ield R eversal ( SFR ) and F ast F ield R eversal ( FFR )
measurements, hence the name ‘ Mixed Mode Measurement ’.
C H A P T E R 1 5
Z e t a s i z e r N a n o S e r i e s
P a g e 1 5 . 7
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Zero electroosmosis
Zero electroosmosis
Stationary
Layer
ILL
6752