Classical activation analysis of fluorine by thermal neutrons has a limited application because of frequent interference from
chlorine, the short half life20F (11.4 s) and too high dead time of detectors. A procedure is described for fluorine determination using19F (n,p)19O reaction. Use of a boron carbide shield has no effect on the activity of19O (boron ratio −1) but considerably reduces background and interference due to18O (n, γ)19O reaction. The technique has been successfully applied to the determination of fluorine in organic compounds even in the
presence of large amounts of chlorine and oxygen.