Use automatic standard addition – Metrohm 797 VA Computrace User Manual

Page 259

8.7 Standard addition technique

797 VA Computrace – Software

247

8. Select

the

Determination

tab (see section 5.2) and enter

Sample

identifier

Sample amount

Cell volume

, and the number of

spiked solutions in the

No. of cells

field.

9. Select

the

Substances

tab (see section 5.2) and make sure that

for each substance entered in the table the concentrations of
the spiked sample solutions are defined in the

CELL CONCEN-

TRATIONS

window which is opened by clicking on the

button.

10. Close the

EDIT WORKING METHOD PARAMETERS

window by

clicking

11. Place the sample solution in the measuring vessel at the 797

VA Computrace stand.

12. Click on

MAIN WINDOW

/ Window / Monitor

to open

the

MONITOR

window.

13. Start the measurement by clicking the

icon in the

MAIN

WINDOW

or the

button in the

MONITORING

win-

dow.

14. Enter the

Sample ID

(used as part of the determination file na-

me) in the

PLACE SAMPLE

window and click

15. Each time a solution exchange is required in the

BATCH SOLU-

TION 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 analyte

is added once or several times to the sample using 700/800 Dosi-
nos, or 685/805 Dosimats. Proceed as follows:

1. Install Dosing Devices to the 797 VA Computrace stand (see

How to Install Dosing Devices for automatic addition, section
8.1).

2. Click on

MAIN WINDOW

/ Mode / Determination

3. Click on

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, section 8.4).

5. Select

Standard addition

in the

Calibration

field of the

WORK-

ING METHOD SPECIFICATIONS

window.

6. Select

Automatic

for

Addition

in the

WORKING METHOD SPECI-

FICATIONS

window.

7. Click

to open the

DOSINOS

window.