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258
The major advantage of this method is that the M-[
η
] relationship is obtained
together with – but
independent
of - the M-R
G
relationship. The new data is
basis for further analyses.
Just as for M or R
G
, the distribution of intrinsic viscosities form the basis for
calculating [
η
]
n
, [
η
]
w
etc. Which average corresponds to the ‘standard’ intrinsic
viscosity which is determined in a conventional experiment, i.e. determining
η
sp
/c for different concentrations and extrapolating to c = 0?
The ‘standard’ intrinsic viscosity corresponds to [
η
]
w
. This is easily shown
since
η
sp
is additive:
Each elution slice:
η
[ ]
i
≈
η
sp
,
i
c
i
⇒
η
sp
,
i
=
η
[ ]
i
c
i
Total:
η
sp
=
η
sp
,
i
i
∑
and
c
=
c
i
i
∑
⇒
η
[ ]
=
lim
c
→
0
η
sp
c
=
lim
c
→
0
η
sp
,
i
i
∑
c
i
i
∑
=
lim
c
→
0
η
[ ]
i
c
i
i
∑
c
i
i
∑
=
η
[ ]
w
Thus, a SMV experiment also yields the intrinsic viscosity of the injected
sample (in addition to its distribution).
10
100
1,000
10,000
100,000
1,000,000
10,000,000
15
20
25
30
V (ml)
R
g
(nm)
[
!
] (ml/g)
M (g/mol)
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
10
15
20
25
V (ml)
R
g
(nm)
[
!
] (ml/g)
M (g/mol)
SEC-MALLS with viscosity detector: Alginate with M
w
= 200.000 Da (left)
and M
w
= 38.000 Da (right). Note different colums were used in the two
cases