NAVI F-52, Instruction Manual

Page: 81 / 270

Chapter 5 Ion Measurement (F-53,55)
5.3 Measurement Using Standard Addition Method
68 HORIBA
●
General Cautions for Standard Addition Method
In order to obtain more accurate and reliable data, pay attention to the following points:
●
No ion of small coexisting tolerance limit.
" Effect of coexisting substance" page 230
●
No interfering ions with a high selective coefficient should coexist.
●
In the STANDARD ADDITION 2 and SAMPLE ADDITION 2 mode, the target ion
concentration in the sample and the electric potential slope of the ion electrode
are obtained with approximation formulas. Therefore, it is not necessary to per-
form calibration or check the electric potential slope before measurement. How-
ever, if the linearity of the ion electrode used is low, if the electric potential slope
is greatly different from the theoretical value (Nernst coefficient), or if a decrease
in the concentration after addition is specified, then accurate measurement
results may not be obtained.
5.3.1 Measuring Ion Concentration in Standard Addition 1 Mode
This mode is used to obtain the concentration of the ion species under measurement by adding
a small amount of the target ions to the sample solution once, thus increasing the ion
concentration of the target component, and then measuring the change in electric potential at
that time.
●
Setting the measurement mode
1.
In ION Measurement screen, press
F1 (ION SETUP).
The ION SETUP screen appears.
2.
In the measurement item, press
←
or
→
key, select the addition
method, and then press the
ENTER key.
3.
Press F4 (RETURN).
The ION Measurement screen (for the
Ion addition measurement) appears.
4.
Press
←
or
→
key to select (1)
SINGLE of the known addition
method, and press the ENTER
key.
In performing the measurement by the
addition method, no setup for such
parameters, as Ion type, Electrode model,
Electrode lot, and/or alarms.