An intercomparison on radionuclides in environmental samples, Baltic-Danish co-operation project on radiation protection 2001-2003.

Sixteen laboratories participated in an intercomparison exercise carried out in 2003 on laboratory analyses of radionuclides in environmental samples. The sample types included seawater, lake water, soil, dry milk and seaweed and the exercise involved the radionuclides ¹³⁷Cs, ⁹⁰Sr, ⁶⁰Co, ^239,240Pu, ²⁴¹Am, ²²⁶Ra, ²³²Th and ⁴⁰K. The evaluation of analytical performance was based on comparison with median values, a 10% target standard deviation and statistical tests at the 99% level. For ¹³⁷Cs the results from 10 out of 16 laboratories passed the evaluation tests. For ⁹⁰Sr the results from 5 out of 12 laboratories passed the evaluation tests. For ⁶⁰Co, ^239,240Pu and ²⁴¹Am two laboratories submitted results and both passed the tests. For the natural radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K, only a few laboratories did not pass the tests. For all radionuclides combined, the results from 6 out of 16 laboratories passed the evaluation tests. The results indicate that for several of the laboratories there is room to improve the analytical quality on radionuclides in environmental samples to match an uncertainty corresponding to a relative standard deviation of 10%.