Determination of uranium in urine by inductively coupled plasma mass spectrometry with pneumatic nebulization

Abstract

An analytical method using inductively coupled argon plasma mass spectrometry with pneumatic nebulization sample introduction for the determination of uranium in urine is described. The urine samples were diluted 1+19 (1% HNO₃ in Milli-Q water) before analysis. Standard additions calibration with iridium (¹⁹³Ir) as an internal standard was used to compensate for undesirable matrix effects. The additions to the diluted samples were 0.1, 0.5, 1.0 and 2.0 ng l^–1, equivalent to 2, 10, 20 and 40 ng l^–1in undiluted urine. The detection limit of the method is 0.32 ng l^–1, which is sufficiently low to measure uranium in non-exposed subjects. The precision at the 8.9 ng l^–1 level was 3.9% (RSD), and at the 28.9 ng l^–1 level 2.0%. The recovery for 20 ng l^–1 added to ten different samples was 101.5%. Urine samples from 18 non-exposed subjects were analysed. The mean concentration found was 16.1 ng l^–1 (median=15.1 ng l^–1) with 14.9 ng l^–1 (median=13.5 ng l^–1) for male and 17.2 ng l^–1 (median=17.6 ng l^–1) for female subjects.