For small particles in low dielectric constant media
f
(Ka)
becomes
1.0
and
allows an equally simple calculation. This is referred to as the
Huckel
approximation.
Non-aqueous
meassurements generally use the
Huckel
approximation.
Measuring Electrophoretic Mobility
It is the electrophoretic mobility that we measure directly with the conversion to
zeta potential being inferred from theoretical considerations. How is
electrophoretic mobility measured?
The essence of a classical micro-electrophoresis system is a cell with electrodes at
either end to which a potential is applied. Particles move towards the electrode of
opposite charge, their velocity is measured and expressed in unit field strength as
their mobility.
The technique used to measure this velocity in Malvern’s Zetasizer Nano series
of instruments is
Laser Doppler Velocimetry
.
Laser Doppler Velocimetry
L
aser
D
oppler
V
elocimetry (
LDV
) is a well established technique in engineering
for the study of fluid flow in a wide variety of situations, from the supersonic
flows around turbine blades in jet engines to the velocity of sap rising in a plant
stem.
In both these examples, it is actually the velocity of tiny particles within the fluid
streams moving at the velocity of the fluid that we are measuring. Therefore,
LDV is well placed to measure the velocity of particles moving through a fluid in
an electrophoresis experiment.
The receiving optics is focussed so as to relay the scattering of particles in the cell.
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 . 5
-
-
+
+
+
+
+
+
-
-
-
-
Electrode
Electrode
Capillary
ILL
6750
Summary of Contents for Zetasizer Nano Series
Page 7: ...Part 1 Operators guide Part 1 Operators guide...
Page 8: ......
Page 9: ...Introduction to this manual Introduction to this manual C H A P T E R 1...
Page 10: ......
Page 16: ...C H A P T E R 1 Z e t a s i z e r N a n o S e r i e s Page 1 6 M A N 0 3 1 7...
Page 17: ...What is the Zetasizer Nano What is the Zetasizer Nano C H A P T E R 2...
Page 18: ......
Page 26: ...C H A P T E R 2 Z e t a s i z e r N a n o S e r i e s Page 2 8 M A N 0 3 1 7...
Page 27: ...How does the Zetasizer Nano work How does the Zetasizer Nano work C H A P T E R 3...
Page 28: ......
Page 51: ...Making measurements A tutorial Making measurements A tutorial C H A P T E R 4...
Page 52: ......
Page 78: ......
Page 90: ...C H A P T E R 5 Z e t a s i z e r N a n o S e r i e s Page 5 12 M A N 0 3 1 7...
Page 91: ...Sample Preparation Sample Preparation C H A P T E R 6...
Page 92: ......
Page 100: ...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 Page 6 8 M A N 0 3 1 7...
Page 101: ...Maintenance Maintenance C H A P T E R 7...
Page 102: ......
Page 107: ...Part 2 Supervisors guide Part 2 Supervisors guide...
Page 108: ......
Page 109: ...Security Security C H A P T E R 8...
Page 110: ......
Page 118: ...C H A P T E R 8 Z e t a s i z e r N a n o S e r i e s Page 8 8 M A N 0 3 1 7...
Page 119: ...Using SOPs Using SOPs C H A P T E R 9...
Page 120: ......
Page 152: ......
Page 161: ...Exporting results Exporting results C H A P T E R 1 1...
Page 162: ......
Page 168: ...C H A P T E R 1 1 Z e t a s i z e r N a n o S e r i e s Page 11 6 M A N 0 3 1 7...
Page 169: ...Creating custom reports Creating custom reports C H A P T E R 1 2...
Page 170: ......
Page 183: ...Size theory Size theory C H A P T E R 1 3...
Page 184: ......
Page 193: ...Molecular Weight theory Molecular Weight theory C H A P T E R 1 4...
Page 194: ......
Page 200: ...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 Page 14 6 M A N 0 3 1 7...
Page 201: ...Zeta Potential theory Zeta Potential theory C H A P T E R 1 5...
Page 202: ......
Page 215: ...Part 3 Appendices Part 3 Appendices...
Page 216: ......
Page 217: ...Health and Safety Health and Safety A P P E N D I X A...
Page 218: ......
Page 223: ...Specification Specification A P P E N D I X B...
Page 224: ......
Page 227: ...Site requirements f r o m M A N 0 3 1 7 I s s u e 1 0 Site requirements A P P E N D I X C...
Page 237: ...Installation Installation A P P E N D I X E...
Page 238: ......
Page 241: ...Regulatory Statements Regulatory Statements A P P E N D I X F...
Page 242: ......
Page 246: ...A P P E N D I X F Z e t a s i z e r N a n o S e r i e s Page F 4 M A N 0 3 1 7...
Page 247: ...Index Index...
Page 248: ......