Elimination of the background signal in tooth enamel samples for EPR-dosimetry by means of physical–chemical treatment

A method of elimination of the background EPR signal in tooth enamel is proposed. This method implies treatment of enamel powder by highly active reduction reagent hydrazine with subsequent washing out by ethanol-water solution. Such treatment results in reducing both the native background signal (which is assumed to be originated by the organic component) and the mechanical induced EPR signal in enamel. Testing of the efficiency of hydrazine treatment is made for different sizes of enamel powder. It is shown that the optimal results are obtained for a powder fraction of about 100–200 μm. The radiation-induced EPR signal in enamel is practically not changed after treatment by hydrazine.