210Pb/210bi detection in waters by cherenkov counting – perspectives and new possibilities

Abstract

The measurement of 210Pb activity concentration via its product 210Bi, high-energy beta emitter capable of producing Cherenkov radiation in waters, by liquid scintillation counter Quantulus 1220 has been explored. Without the chemical pre-treatment, the detection limits have been evaluated and possibilities to further decrease MDA value have been considered. Prolonging the counting time coupled to the sample's evaporation prior to counting can enable the achievement of the detection limits below maximal permitted levels recommended by the international legislation. The impact of sodium salicylate addition to the counting vials on the detection efficiency and consequently MDA value has been tested. Sodium salicylate application is associated with the certain complications during sample preparation, here we propose salicylate-based ionic liquids instead. We present an innovative experiment that explores the influence of the addition of a synthesized 2-hydroxypropan-1-amminium salicylate to the counting vials in order to decrease MDA parameter. Furthermore, the interference with 226Ra Cherenkov spectra was assessed and the possibility to evaluate its contribution to 210Pb/210Bi spectra has been proposed. The potential of 210Pb screening in the samples without the chemical isolation of 210Pb has not been thoroughly considered in the literature so far. 210Pb screening of a few spiked samples and real samples collected in the vicinity of mine was carried out, thus the obtained results demonstrate the method's evaluation and set its limitations.