Rapid monitoring of 241Am in small amount of sediment samples by combining extraction chromatography for highly efficient separation of interfering and matrix elements and ICP-MS/MS measurement

Abstract

The analysis of 241Am in environmental samples is of great importance in the fields of geological repositories and radiation protection. The triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) has a strong analytical and interference removal capability for long half-life radionuclides. In this study, the ability of ICP-MS/MS to determine ultra-trace level of 241Am in environmental samples was further explored. The instrumental sensitivity for Am detection was significantly improved (ca. 20 times) by employing an APEX-Ω high efficiency introduction system. The gases of O2 and He were introduced to the reaction cell for eliminating of interferences and Am was detected as AmO+ ions. High separation factors (>2000) of Am and Pu were obtained at proper gas flow rates by chemical resolution of the instrument. Meanwhile, the background signals caused by possible polyatomic interferences for 241Am and 243Am were sufficiently reduced. A simple and rapid chromatographic separation method for purposeful and efficient separation of 241Am from matrix and interfering elements was developed. The overall chemical recoveries were about 68% and the detection limit of 241Am for the established method was 0.18 fg g−1 (equivalent to 0.02 mBq g−1). Several marine sediment reference materials were analyzed for the validation of the method and the results showed that this method was suitable for the determination of 241Am in solid environmental samples. The method was finally applied to real marine sediment samples collected in the western North Pacific after the Fukushima nuclear accident.