Metrohm 757 VA Computrace - Manual (Page 158)

7 How to ...?
757 VA Computrace – Software
148
13. Start the measurement by clicking the icon in the MAIN
WINDOW or the button in the MONITORING window.
14. Enter the Sample ID (used as part of the determination file
name) in the PLACE SAMPLE window and click <OK> .
15. Each time a solution exchange is required in the BATCH SO-
LUTION EXCHANGE window, replace the measuring solution
by the next spiked sample solution.
Use automatic standard addition
In the automatic standard addition, a known amount of the ana-
lyte is added once or several times to the sample using 665 or
765 Dosimats. Proceed as follows:
1. Install Dosimats to the 757 VA Computrace Stand (see How to
install Dosimats).
2. Click on or MAIN WINDOW / Mode / Determination .
3. Click on or MAIN WINDOW / Window / Working method
specification to open the WORKING METHOD SPECIFICATIONS
window.
4. Load the desired method into the WORKING METHOD SPECIFI-
CATIONS window (see How to load a method).
5. Select Standard addition in the Calibration field of the WORKING
METHOD SPECIFICATIONS window.
6. Select Automatic in the Addition field of the WORKING METHOD
SPECIFICATIONS window.
7. Click to open the DOSIMATS window.
8. Check the Dosimats which are should be used for standard
addition in the Dosimat used field (see Dosimats, section 5.2).
9. Close the DOSIMATS window by clicking <OK> .
10. Click to open the EDIT WORKING METHOD PA-
RAMETERS window.
11. 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.
12. 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. The
No. of the standard solution
must be identical to the number of the Dosimat used for
automatic addition of this solution.