In the field of chemical determination of fluorine, two distinct developments have been introduced in these several years. One is a new dye “alizarin complexan” originated by Belcher et al, the cerium or lanthanum chelate of which reacts with fluorine producing specific lilac blue complex. It involves an unique positive color reaction as compared with the routine dye bleaching method. Hence, it is most suitable for the microdetermination of fluorine.
The other device is the introduction of Conway's microdiffusion method into this field by Singer and Armstrong. It is indispensable for the isolation of microamount of fluorine from the interfering factors in biological specimens.
The author intended to combine these two new features into a systematic procedure for the estimation of fluorine of either very low concentration in water or micro-and submicrogram of fluorine in very minute amount of biological specimens. It was accomplished by the adoption of extraction procedure of blue fluoro-complex by organic solvent after Hall and self-devised polyethlene microdiffusion bottle with a “chimney”. A polyethylene straw was attached to the cap like a chimney to allow the heat-expanded air to escape.
The versatility of the method is now under experiment by its use in various cases. The results of several experiments thusfur obtained are summarized as follow:
1. The water containing very low concentration of fluorine (below 0.1 ppm) was satisfactorily analy by the new method with the error of 3% in city water supply and 12% in well water, while Zr-S. DNS method showed the error of 45% and 40% respectively.
2. Using only 2ml of plasma or saliva, the fluorine content was determined without difficulty, the a erage value being 0.16ppm and 0.18ppm respectively.
3. The fluorine content in surface enamel of extracted teeth was determined. A small filterpaper disc (diameter 5mm) containing 2N perchloric acid was fixed to the enamel surface for two minutes. The disc was then put into the diffusion bottle and analysed.
In permanent teeth, the labial surface of incisors contained fluorine in concentration of 0.12μg/10mm2 and the lingual surface 0.15μg/10mm2, while in deciduous teeth the values were 0.07 and 0.11μg/10mm2 respectively.
4. The application of the method to human teeth in situ, the so-called enamel biopsy, is now under experiment using milder acid attack.