A multielement proton induced gamma emission (PIGE) method has been developed to analyze fluoride in water residues obtained by evaporation. In this method, 200 mL of water sample mixed with 100 mg of cellulose powder is evaporated, and the residue is made into standard pellets that are then irradiated with a 2.9 MeV proton beam. The emitted y-rays from the decay
of the excited fluorine nuclei are detected with a high resolution, high purity germanium (HPGe) detector and analyzed using a commercial gamma ray spectrum unfolding software. For concentration calibration, synthetic fluoride standards of different concentrations, as NaF in a CaC03 matrix, were prepared and homogenized by dispersing them in methanol. The method thus developed was applied to determine the concentration of fluoride in 85 water samples collected from different city supplies of Bangladesh. The concentration ranged from 0.03 to 1.10 mg/L with the mean of 0.32 ± 0.21 mg/L.
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