Fluorine determination in biological and environmental samples with INAA using fast neutrons from a p(19 MeV) + Be neutron generator

We present a new activation method based on the ¹⁹F(n,2n)¹⁸F reaction using fast neutrons produced by a p(19 MeV) + Be accelerator-driven fast neutron source providing continuous neutron spectrum up to 17 MeV with a neutron fluence rate of approximately 9 × 10¹⁰ cm^-2 s^-1 at a 12-µA proton beam current. We describe elimination of interferences in measurement of ¹⁸F, a pure positron emitter with T_1/2 = 1.83 h. We present results of fluorine determination for several biological and environmental reference materials with the new procedure and compare them with those achieved by other methods in terms of limits of detection, accuracy and precision, where available. (author)