Introduction
The aim of this chapter is to describe the basic
Molecular weight
principles
behind the Zetasizer Nano. This will help in understanding the meaning of the
results achieved.
The chapter is divided into two major sections.
What is Static light scattering?
and
The Debye plot
. The first section describes the molecular weight theory,
while the second shows how a molecular weight measurement is displayed.
What is Static light scattering?
The Zetasizer Nano series performs Molecular weight measurements using a
process called
S
tatic
L
ight
S
cattering (
SLS
).
S
tatic
L
ight
S
cattering (
SLS
) is a non-invasive technique used to characterise the
molecules in solution.
In a similar way to Dynamic light scattering - the Size theory in chapter 13 - the
particles in a sample are illuminated by a light source such as a laser, with the
particles scattering the light in all directions. But, instead of measuring the time
dependent fluctuations in the scattering intensity, Static light scattering makes use
of the time-averaged intensity of scattered light instead.
The intensity of light scattered over a period of time, say 10 to 30 seconds is
accumulated for a number of concentrations of the sample. This time averaging
removes the inherent fluctuations in the signal, hence the term ‘Static Light
Scattering’.
From this we can determine the
Molecular weight (MWt)
and the
2
nd
Virial
Coefficient (A
2
)
.
The
2
nd
Virial Coefficient (A
2
)
is a property describing the interaction strength
between the particles and the solvent or appropriate dispersant medium.
.
For samples where
A
2
>0
, the particles ‘like’ the solvent more than itself,
and will tend to stay as a stable solution.
.
When
A
2
<0
, the particle ‘likes’ itself more than the solvent, and therefore
may aggregate.
.
When
A
2
=0
, the particle-solvent interaction strength is equivalent to the
molecule-molecule interaction strength – the solvent can then be described
as being a
theta
solvent.
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
P a g e 1 4 . 1
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: ......