APPARATUS
Eppendorfpipettes
Ionselective electrode for fluoride (Orion)
pH-meter with mV-display
Magnetic stirrer
REAGENTS:
TISAB-III-Buffer : 300g Na-Citrate * 2 H2O
22g Titriplex IV (1,2-Cyclohexylendinitrilotetra-acetic-acid-Monohydrate)
60g NaCl
make up to 1000 dm3 with aqua bidest.
STANDARDS:
IAPSO-seawater standard (theoretical content of fluorid: 69,5 µM)
Stockstandard: NaF-Standard (52,636 mM) (Merck)
Work standards: Dilute the stock-standard with IAPSO in different relations to obtain standards with different concentrations for a calibration.
Calibration area: 69,5- 174,76 µM/l
PROCEDURE:
1000 µl sample or standard are mixed with 1000 µl TISAB-III-Buffer on the magnetic stirrer. After 5 minutes (value has to be constant!) the result can be read in mV.
