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

MAIN WINDOW

/ Mode / Determination

2. Click on

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

11. Close the

EDIT WORKING METHOD PARAMETERS

window by

clicking

12. Place the sample solution in the measuring vessel at the 757

VA Computrace Stand.

13. Click on

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.