Determination of 210Pb, 210Po, 226Ra, 228Ra and uranium isotopes in drinking water in order to comply with the requirements of the EU 'Drinking Water Directive.

The European Union published in 2013 a new Drinking Water Directive with stricter requirements for measuring natural radioactivity. In order to adhere to this, a method for sequential separation of 210Pb, 210Po, 238U and 234U in drinking water was applied using UTEVA® and Sr resins. Polonium-210, 238U and 234U were quantified using alpha-particle spectrometry and 210Pb using liquid scintillation counting. Radium-226 and 228Ra were determined using 3M Empore Radium RAD Disks, and their quantification was done using a Quantulus™ 1220 liquid scintillation counter.

A performance comparison of nine selected liquid scintillation cocktails.

Sample load capacity, sample compatibility, influence of sample load on (3)H/(14)C counting efficiency, background count rate, figure of merit, quench resistance, and sample stability for nine selected, commercially available, liquid scintillation cocktails are presented in this study. The cocktails tested are Ecoscint A, Insta-Gel Plus, OptiPhase Hisafe 3, OptiPhase Trisafe, Ready Gel, SafeScint 1:1, Ultima Gold, Ultima Gold LLT, and Ultima Gold XR. For the data acquisition a Packard TriCarb Model 1900CA and a Quantulus 1220 liquid scintillation counter is used. All samples are prepared in either 20mL low potassium, borosilicate glass vials or 20mL high density, polyethylene vials. The aim of the full comparison study is to determine a single cocktail that best suits all measurement requirements of the liquid scintillation laboratory at SCK.CEN for the determination of low levels of radioactivity in biological and environmental samples. The results published in this report are intended to help other laboratories in selecting a cocktail fit for their purposes or to set up a similar study.