Improving ²¹⁰Po source preparation for alpha spectrometry: Neodymium hydroxide micro-precipitation

A method for alpha source preparation of actinides for alpha spectrometry using micro-precipitation with neodymium hydroxide (Nd(OH)₃) was adapted for ²¹⁰Po. The method requires chemical separation prior to alpha source preparation and is therefore most suitable for samples with a complex chemical matrix. Alpha peak resolution of less than 50 keV at full-width-half-maximum (FWHM) is routinely achieved and alpha source preparation times are reduced compared to many auto-deposition methods. Enhanced chemical separation of Po from Cu and Pb was achieved by exploiting differences in complexation chemistry using alternative neutralising agents. The method is thus highly suitable for samples with high Cu concentrations or where determination of ²¹⁰Pb is undertaken after chemical separation and ingrowth of ²¹⁰Po using stable Pb as a tracer. The method has a high sensitivity to the presence of Fe such that the chemical separation technique used prior to alpha source preparation should ensure Fe is adequately separated. The method has proven to be robust for complex sample types after chemical separation of ²¹⁰Po, with relatively uniform distribution of Po on prepared sources. Chemical recovery was comparable to other sample preparation methods for ²¹⁰Po analysis across a range of environmental samples, including biota, marine sediment, seawater, surface water, and groundwater sourced drinking water.