6 standard addition technique – Metrohm 757 VA Computrace User Manual
Page 156
7 How to ...?
757 VA Computrace – Software
146
7.6
Standard addition technique
Use manual standard addition without solution exchange
In the manual standard addition without solution exchange, a
known amount of the analyte is added once or several times to
the sample using a pipette. Proceed as follows:
1. Click on
or
MAIN WINDOW
/ Mode / Determination
.
2. Click on
or
MAIN WINDOW
/ Window / Working method
specification
to open the
WORKING METHOD SPECIFICATIONS
window.
3. Load the desired method into the
WORKING METHOD SPECIFI-
CATIONS
window (see How to load a method).
4. Select
Standard addition
in the
Calibration
field of the
WORKING
METHOD SPECIFICATIONS
window.
5. Select
Manual
in the
Addition
field of the
WORKING METHOD
SPECIFICATIONS
window.
6. Select
Batch
in the
Technique
field of the
WORKING METHOD
SPECIFICATIONS
window.
7. Click
to open the
EDIT WORKING METHOD PA-
RAMETERS
window.
8. Select the
Determination
tab (see section 5.2) and enter
Sam-
ple identifier
,
Sample amount
,
Cell volume
, and the number of
standard additions in the
No. of additions
field.
9. Select the
Substances
tab (see section 5.2) and make sure
that for each substance entered in the table the number of the
single or mixed standard addition solution, its concentration
and its volume is defined.
10. If the standard addition should be done with variable addition
volumes, click the button in the
Volume
column to open
the
EDIT VARIED ADDITION
window, enter the variable addition
volumes in the
Addition
fields, and close this window by click-
ing
<OK>
.
11. Close the
EDIT WORKING METHOD PARAMETERS
window by
clicking
<OK>
.
12. Place the sample solution in the measuring vessel at the 757
VA Computrace Stand.
13. Click on
or
MAIN WINDOW
/ Window / Monitor
to open the
MONITOR
window.
14. Start the measurement by clicking the
icon in the
MAIN
WINDOW
or the
button in the
MONITORING
window.