A micromethod for the determination of fluoride in blood plasma and saliva

A simple and accurate technique for the determination of fluoride (F-) in capillary-sampled blood is presented. The method is based on the known addition-slope determination technique using the fluoride electrode. No calibration curve or calibration of the electrode is required. A standard deviation of 1.3-5.6% in the range 300-10 ng F/ml was given by 259 duplicate determinations on human plasma. Measurements of parotid saliva showed that it was possible to analayze fluoride concentrations as low as 4 ng F/ml with good reproducibility. The results also show that a 150 microliter sample is sufficient for fluoride determination with high accurary. This method can easily be used in clinical laboratory.