FLUORINE DETERMINATION IN DIET SAMPLES USING CYCLIC INAA AND PIGE ANALYSIS

Fluorine is an important trace element for life and human well-being. Food, in general, provides about 40 percent of the fluorine intake in the human body. In order to measure fluorine levels in human diet samples, Instrumental Neutron Activation Analysis (INAA) and Proton Induced Gamma-ray Emission (PIGE) analysis were used. Reactions (F(n, gamma)F)-F-19-F-20 and (F(n,p)O)-F-19-O-19 were employed for determination of the fluorine concentration using a reactor neutron spectrum and epithermal neutrons. Corrections were made for the sodium matrix interference caused by the (Na(n, alpha)F)-Na-23-F-20 threshold reaction in the case of reactor neutron cyclic activation analysis and for the oxygen interference via (O(N, gamma)O)-O-18-O-19 reaction when using the epithermal cyclic NAA method. The fluorine content of the diet samples was also determined by PIGE analysis making use of the resonance reaction (F(p, alphagamma)O)-F-19-O-16 at 872 keV. Cyclic Neutron Activation Analysis (CNAA) when combined with mass fractionation was found to be the most suitable for determination of low concentration of fluorine, through the (F(n, gamma)F)-F-19-F-20 reaction with a detection limit of 2.2 ppm in Bowen's Kale elemental standard.