Technetium-99 in “instant”99mTc-pertechnetate

The⁹⁹Tc-content in^99mTc-pertechnetate separated from⁹⁹Mo by distillation or extraction has been studied with a plastic scintillation detector. The identification of the measured activity was achieved by beta-spectrometry, chemical separation and half-life studies. The frequency distribution of the⁹⁹Tc/^99mTc-ratios in the different samples was observed to be log-normal. The most likely activity ratio was 0.4·10⁻⁶, the maximum value being 5·10⁻⁶. The specific activity of “instant” pertechnetate is approximately a factor of 60 lower than that normally recorded in pertechnetate derived from daily eluted column generators. The low specific activity of “instant” pertechnetate is primarily explained by the long time between separation and usage and secondly by the low yield of Tc in the distillation and extraction processes. In several of the “instant” pertechnetate solutions the carrier concentration exceeded the reductive capacity of the stannous ions in “kits” with small amounts of Sn(II) in usable form.