Simple ⁴⁰K removal by acidified water leaching for estimating low levels of radiocesium in fishery products following Fukushima Dai-ichi Nuclear Power Plant accident

We developed a simple method for ⁴⁰K removal by acidified water leaching combined with ammonium phosphomolybdate coprecipitation, for estimating low levels of radiocesium in Japanese flounder. ⁴⁰K removal from ashed samples was approximately 98%, with the radiocesium yield of ~98%. The treatment reduced the γ-spectral baseline to ~1/5 at ground and ~3/100 at underground levels (1.04 and 0.11 cph/keV, respectively). Faint signal of ¹³⁴Cs, which is embedded in the Compton continuum of ⁴⁰K in an untreated sample, was detected. - Highlights: • ⁴⁰K removal treatment helps in detecting low-level ¹³⁴Cs in Japanese flounder. • ~98% of ⁴⁰K was removed from ashed sample with ~98% yield of radiocesium. • Detection of faint ¹³⁴Cs signal embedded in the baseline in untreated samples.