Metrohm tiamo 2.4 Manual - Manual (Page 952)

5.6 Commands
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936 ￭￭￭￭￭￭￭￭
tiamo 2.4
￭ STDADD man
Standard addition with manual addition of the standard addition solu-
tion.
￭ STDADD dos
Standard addition with addition of the standard addition solution from
a dosing device.
￭ STDADD auto
Standard addition with automatic addition of the standard addition
solution from a dosing device in such a way that a constant potential
difference results.
5.6.4.2 Standard addition - Overview
Menu item: Method ▶ Insert ▶ New command... ▶ Measure
Recommendation
In order to guarantee a reliable evaluation of the standard addition, care
must be taken to ensure that the buret volume and the concentration of
the standard solution are adjusted to the respective measuring conditions.
The individual addition volumes must be selected in such a way that the
potential difference is at least 15 mV after each additive step. At least four
volume additions should be carried out.
Table 44 Recommended concentrations of the standard solution for
the standard addition
Buret volume in mL c
Standard solution
: c
Sample
5 40 : 1
10 20 : 1
20 10 : 1
50 5 : 1
Example of a standard addition
NOTE
This example is valid for standard additions with any type of ion-selec-
tive electrodes.
Sample concentration 5 mg/L
Buret volume 10 mL
Sample size 10 mL
ISA/TISAB 10 mL