抄録
Total fluoride (F) determination in dental plaque is rather complicated because of its small quantities and low F concentration smapled from the individual. Full dissociation of the bound F in dental plaque is also required for the assay by F sensitive electrode.
Recently, AlF (aluminum monofluoride) molecular absorption spectrometry was developed for the ultratrace analysis of F. An application of this method to the determination of total F in dental plaque was investigated.
The results were as follows:
1) The AIF absorbance was linearly increased by increase of F (5-50ng/ml) added to sample solutions (0.5-2.1mgdry plaque/ml). The regression coefficients of sample solutions were almost equal to that of the standard solution. The sensitivity was 0.066ng F per 20μl standard solution at the 1% absorption level, and the relative detection limit was 0.0036ppm (3.6ppb).
2) The variations of absorbance increased with the plaque amounts, but the recovery of fluorine from sample solution was not affected by the amounts of plaque contained.
3) The coefficient of variation of F concentration in small plaque samples (approximately 1mg dry weight) ranged from 8.6 to 15.9%, and F concentrations of five pooled plaque samples ranged from 8.0 to 12.3ppm (dry weight).
These experiments suggest that AlF molecular absorption spectrometry is useful for analysis of total F in dental plaque, especially in small samples and at low F concentrations.
