13
Appendix
13.1
Refractive index of pure water (15...40 °C)
Temp
°
[
C] n
D
15
1.3334
16
1.3333
17
1.3332
18
1.3332
19
1.3331
20
1.3330
21
1.3329
22
1.3328
23
1.3327
24
1.3326
["Handbook of Chemistry and Physics, 56th Edition"]. Values divided by the
refractive index of air at the corresponding temperatures, according to the for-
mula given in ["Handbook of Chemistry and Physics, 75th Edition"].
13.2
Brix%
Brix% represents the concentration in weight percent of a mixture of pure sucrose
and water (g sucrose per 100 g solution) and is used to express the % weight
concentration of sucrose solutions in general. Brix% is calculated from the mea-
sured refractive index using a concentration table stored in the instrument (source:
20
th
conference of the International Commission of Uniform Methods for Sugar
Analysis ICUMSA). The results are given at the standard reference temperature of
20 °C using the temperature dependence for these solutions from the same source.
The refractive index and the prism surface temperature are thus measured and
the Brix% is calculated from the tables.
Note:
When substances other than sucrose are present in the sample the
result in Brix% will not indicate the real sucrose concentration.
METTLER TOLEDO Refracto 30PX/GS
Temp
°
[
C] n
D
25
1.3325
26
1.3324
27
1.3323
28
1.3322
29
1.3321
30
1.3319
31
1.3318
32
1.3317
33
1.3315
34
1.3314
Appendix
Temp
°
[
C] n
D
35
1.3312
36
1.3311
37
1.3310
38
1.3308
39
1.3307
40
1.3305
23