4. Conclusion
A simple procedure has been developed for the determination of fluorine in tea using the molecular absorption of CaF after electrothermal vaporization in a graphite tube furnace. The great advantage is that only calcium has to be added in a 20-fold molar excess over fluorine as the molecule-forming agent, and no other modifier was necessary. The only disadvantage is that the graphite tubes last for only about 100 determinations due to the well-known reaction of calcium with graphite under the formation of a carbide, which decomposes upon the addition of water. The sensitivity of the proposed method is lower than that described for the GaF molecular absorption, but it perfectly served the purpose, and the CaF absorption line at 606.440 nm might well be applicable for the determination of fluorine in other types of samples in case the analyte concentration is high enough.