16
Fluoride Ion Selective Electrode User Guide
Direct Calibration
Setup
1. Prepare the electrode as described in the
Electrode
Preparation
section. If using the 9409BN or 9409SC half-
cell fl uoride electrode with the 900100 reference electrode,
fi ll the reference electrode with Cat. No. 900001. If using
the 9609BNWP combination fl uoride electrode, fi ll the
electrode with Cat. No. 900061.
2. Connect the electrodes to the meter.
3. Prepare at least two standards that bracket the expected
sample range and differ in concentration by a factor of ten.
Standards can be prepared in any concentration unit to suit
the particular analysis requirement. All standards should
be at the same temperature as the samples. For details on
temperature effects on electrode performance, refer to the
Temperature Effects
section.
Serial Dilutions
Serial dilution is the best method for the preparation of
standards. Serial dilution means that an initial standard is
diluted, using volumetric glassware, to prepare a second
standard solution. The second standard is similarly diluted to
prepare a third standard, and so on, until the desired range of
standards has been prepared.
1.
To prepare a 10
-2
M NaF standard (190 ppm fl uoride)–
Pipette 10 mL of the 0.1 M NaF standard into a 100 mL
volumetric fl ask. Dilute to the mark with deionized water
and mix well.
2.
To prepare a 10
-3
M NaF standard (19 ppm fl uoride)–
Pipette 10 mL of the 10
-2
M NaF standard into a 100 mL
volumetric fl ask. Dilute to the mark with deionized water
and mix well.
3.
To prepare a 10
-4
M NaF standard (1.9 ppm fl uoride)–
Pipette 10 mL of the 10
-3
M NaF standard into a 100 mL
volumetric fl ask. Dilute to the mark with deionized water
and mix well.
