Determination of U-236 in environmental samples by single extraction chromatography coupled to triple-quadrupole inductively coupled plasma-mass spectrometry

摘要

In order to measure trace U-236 and U-236/U-238 in environmental samples with a high matrix effect, a novel and simple method was developed that makes the digestion and purification procedures compatible with advanced triple-quadrupole inductively coupled plasma-mass spectrometry. A total dissolution of sample with HF + HNO3 + HClO4 was followed by chromatographic separation with a single resin column containing normal type DGA resin (N, N, N', N'-tetra-n-octyldiglycolamide) as the extractant system. The analytical accuracy and precision of U-236/U-238 ratios, measured as (UO+)-U-236-O-16/(UO+)-U-238-O-16, were examined by using the reference materials IAEA-135, IAEA-385, IAEA-447, and JSAC 0471. The low method detection limit (3.50 x 10(-6) Bq kg(-1)) makes it possible to perform routine monitoring of environmental U-236 due to global fallout combined with the Fukushima Daiichi Nuclear Power Plant accident fallout (> 10(-5) Bq kg(-1)). Finally, the developed method was successfully applied to measure U-236/U-238 ratios and U-236 activities in soil samples contaminated by the accident. The low U-236/U-238 atom ratios ((1.50 -13.5) x 10(-8)) and U-236 activities ((2.25-14.1) x 10(-2) mBq kg(-1)) indicate U-236 contamination was mainly derived from global fallout in the examined samples. (C) 2016 Elsevier B.V. All rights reserved.