Determination of ²²⁶Ra in environmental samples by alpha spectrometry. A new separation method based on the rapid co-precipitation of ²²⁶Ra with PbSO₄

A new method to determine ²²⁶Ra by alpha spectrometry from various environmental samples was developed. After sample dissolution, Ra(II) was co-precipitated with PbSO₄, and the precipitate was quickly filtered 1 min later. The rapid filtration of PbSO₄ prevented CaSO₄ and SrSO₄ from precipitating. The Pb(Ra)SO₄ precipitate was re-dissolved using an EDTA solution and the pH was adjusted to 5 with sulfuric acid. Then, a BaSO₄ micro-precipitation was performed to prepare a Ra thin-layer source for measurement of ²²⁶Ra by alpha spectrometry. Excellent decontamination factors were obtained. The method was validated using spiked samples and certified reference materials. (author)