Abstract
Determining trace amounts of total fluorine (F) in biological samples requires tedious and time-consuming pretreatment and measurement. Recently, a new analytical method has been developed by Tsunoda et al. for the determination of subnanogram fluoride based on aluminum monofluoride molecular absorption spectrometry (AlF method). However, this method requires a fairly high level of skill for generating the aluminum monofluoride (AlF) vapor in an electrothermal graphite furnace with two separate injections, one of the Al matrix solution and the other of the sample solution.
In this study, we investigated the operating conditions of the atomic absorption spectrophotometer and the procedures for the determination of F in blood serum by the AlF method. In order to examine the practicability of the AlF method for determining low level F in various samples, we applied both the AlF method and the ashing method (low temperature plasma ashing followed by gas chromatography) to determine the total F in the blood plasma of rats which had been given drinking water containing fluoride; the results obtained by both methods were then compared.
The results were as follows:
1. To increase the sensitivity and reproducibility of AlF analysis, it is important to find the original (optimum) working conditions for the apparatus used since we obtained results which were different from experimental data published in other research.
2. For the sample injection procedure, the two-injection procedure with intervening drying and ashing steps proved unsatisfactory under the conditions we employed. The best results were obtained from one injection of the sample diluted with the Al matrix solution in a ratio of one to one.
3. The composition of the Al matrix solution (amounts of Al and matrix modifier) and the Triton concentrations which were added to the samples seriously effected the intensity of the AlF absorption and its reproducibility.
4. The total F values in the rat plasma determined by the AlF method and those determined by the ashing method showed excellent agreement, even though the values obtained from the AlF method were slightly higher than those from the ashing method in most samples.
5. In conclusion, it was found that the AlF method is a useful means for determining the total F in serum and plasma, although there is the possibility of a serious error when the F content is determined without proper knowledge of the AlF analysis.
