INCREMENTAL METHODS
3.20 KNOWN ADDITION/SUBTRACTION
This menu option will begin a known addition measurement. The sample concentration is calculated using:
Where:
Cu
=
Sample concentration
Cs
=
Standard concentration
Vs
=
Volume of standard
Vu
=
Volume of sample
E
=
Change in electrode potential
S
=
Slope of electrode
To perform a measurement the following procedure should be carried out:
Select KNOWN ADDITION/SUBTRACTION mode using the arrow keys and pressing . Enter the
SETUP... menu using the arrow key and pressing . This menu option gives access to the parameters
relating specifically to a known addition or subtraction measurement.
Select SAMPLE VOLUME using the arrow key. Press . The value will now be highlighted. Adjust
the reading as required using the numeric keys. If a mistake is made the key can be used as a delete key,
starting from the lowest digit. If you wish to alter the entered value keep pressing this key until a blank box
appears. Pressing the key again will default to the original value. Once the correct value is entered pressing
the key will update the display to the new value.
Select STANDARD VOLUME using the arrow key. Press . The value will now be highlighted.
Adjust the reading as required using the numeric keys. If a mistake is made the key can be used as a
delete key, starting from the lowest digit. If you wish to alter the entered value keep pressing this key until a
blank box appears. Pressing the key again will default to the original value. Once the correct value is entered
pressing the key will update the display to the new value.
Select STANDARD CONC using the arrow key. Press . The value will now be highlighted. Adjust
the reading as required using the numeric keys. If a mistake is made the key can be used as a delete key,
Cu
=
Cs. Vs / (Vu + Vs)
10
ES
- Vu / (Vu + Vs)
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