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Refractometry
What is refractometry?
Examples
(continued)
This was pretty easy. Take care, that the brix value considers the temperature and you do not have to apply
a temperature correction.
Let us observe an example that is a little bit more exciting: the brix scale itself. For instance, you have this
table with values at 20.0°C:
We call this seven values the support points of the polynomial fit.
If your calculator is able to compute a best-fit curve, it would show you the following formula:
So if you want to type in the coefficients for the special scale you have to use 0.358 for c
c
. The coefficients c
2
3
Optionally you can even determine a parabola with the least-squares method, the formula would
look like that:
Results compared to the set values:
Refractive Index
1.332986
1.347824
1.363842
1.381149
1.399860
1.420087
1.441928
14
(continued)
(continued)
Refractive Index
1.332986
1.347824
1.363842
1.381149
1.399860
1.420087
1.441928
Brix = 0.358 + 549.396 · r
to c
would be zero.
8
Brix = -1.90 + 682.773 · r - 1167.678 · r
set value
0
10
20
30
40
50
60
Brix
0
10
20
30
40
50
60
2
brix
straight line
parabola
2.0
10.2
19.0
19.9
28.5
30.0
38.7
40.1
49.9
50.1
61.9
59.9
and 549.396 for
1
0.1
9.9
1400700-101 Rev. A
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