Metrohm 907 Titrando - Manual (Page 44)

4.1 Volumetric titration
￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭
36 ￭￭￭￭￭￭￭￭
907 Titrando
15 The next determination can be started as soon as the determination
has been finished and the titration cell has been conditioned (drift
stable) again.
4.1.6 Sample addition
This chapter contains a few notes concerning sample addition. Further
notes can be found in the publications of the reagent manufacturers and
in the Karl Fischer monograph published by Metrohm.
4.1.6.1 Size of the sample size
The sample weight should be small in order to be able to titrate as many
samples as possible in the same electrolyte solution and in order to keep
the titration time short. However, ensure that the sample contains at least
50 µg of H
2
O. The following tables provide clues for the sample size.
Table 1 Approximate sample size in grams (5 mL buret)
Water content of
the sample KF reagent 1 KF reagent 2 KF reagent 5
0.5% 0.1 - 0.9 0.2 - 1.8 0.5 - 4.5
1.0% 0.05 - 0.45 0.1 - 0.9 0.25 - 2.25
5.0% 0.02 - 0.18 0.05 - 0.45
10.0% 0.03 - 0.22
25.0%
50.0%
Table 2 Approximate sample size in grams (10 mL buret)
Water content of
the sample KF reagent 1 KF reagent 2 KF reagent 5
0.5% 0.2 - 1.8 0.4 - 3.6
1.0% 0.1 - 0.9 0.2 - 1.8 0.5 - 4.5
5.0% 0.02 - 0.18 0.04 - 0.36 0.1 - 0.9
10.0% 0.02 - 0.18 0.05 - 0.45
25.0% 0.02 - 0.18
50.0% 0.02 - 0.09