Abstract
A number of techniques and procedures for fluoride analysis and its pretreatment have appeared in the literature. There have been numerous contradictory findings concerning the levels of fluorine in blood serum with different investigators producing widely differing values.
In the previous paper, we reported the suitability and the efficiency of employing a low temperature oxygen plasma ashing as a pretreatment procedure to assess the fluorine content in biological materials.
In this study, to determine the fluorine content values in newborn calf serum we used various analytical methods, either alone or combined with some sort of pretreatment procedure in order to find adequate methods for determining ionizable and total fluorine separately. We then examined the significance of these values.
The following four methods were used for this purpose: (1) direct measurement of ionizable fluorine in calf serum using the fluoride ion-selective electrode; (2) after pretreatment with low temperature oxygen plasma ashing, the fluoride ion-selective electrode method and the gas chromatograph method; (3) fluorine separation by microdiffusion followed by determination with the gas chromatograph; and (4) direct extraction with a solvent (4% TMCS n-hexane) followed by determination with the gas chromatograph.
With the fluoride ion-selective electrode method it was possible to determine the ionizable fluorine without any prior separation or decomposing treatment. To determine the total fluorine in the calf serum, the direct microdiffusion method using a strong acid (60% HClO4) and the direct extraction method proved deficient under the conditions we employed. This suggests the necessity of applying other types of pretreatment. The fluorine level determined by gas chromatography after the application of the low temperature oxygen plasma ashing was the highest among the results we obtained, presumably indicating an actual total fluorine content level in the sample.
