Determination of picogram amounts of 99tc by neutron activation analysis

A post-irradiation procedure for the determination of picogram amounts of ⁹⁹Tc in triply distilled water is described. The ⁹⁹Tc is irradiated in a thermal neutron flux of about 5.10¹³ n cm^-2 sec^-l to produce 16-sec ¹⁰⁰Tc. The chemical purification of the ¹⁰⁰Tc from other radionuclides requires 40–45 sec and the technetium yield is about 53%. The purified ¹⁰⁰Tc is counted in a low-background β-counter.