Direct Potentiometric Determination of Free Fluorion in Tetrafluoroborate with Fluoride Ion Selective Electrode

Sample of tetrafluoroborate was dissolved with ethanol (50+50) solution, and content of F- in the sample solution was determined with fluoride ion selective electrode. It was found that excellent selectivity and good potential response toward F- were achieved by the ion selective electrode, which showed Nernst potential response in the range of 0.5 to 10 μg·L-1 with slop of 61.453 mV·pc-1 in a medium of pH 5.8-6.0 at 25 ℃. Recovery was tested by standard addition method on the base of 3 samples of tetrafluoroborate, results of recovery found were in the range of 96.7%-104% with RSD′s (n=6) in the range of 0.8%-4.2%.