Pu239+240 concentration and isotope ratio (Pu-240/Pu-239) in aerosols during high dust (Yellow Sand) period, Korea

Abstract

Concentration and isotope ratio of Pu were analyzed for aerosols collected at Anmyeondo located in the western coast of Korea using multiple collector inductively coupled plasma mass spectrometer equipped with desolvated micro-concentric nebulizer. Aerosols were collected from June 2001 to April 2002 using high volume air sampler. The samples consist of high dust samples (Yellow Sand), and also low dust samples; maximum Al concentration was 74.2 mu g/m(3) and minimum was 0.17 mu g/m(3). Pu was concentrated using 0.1 ml TEVA resin columns after conc. HNO3 extraction. Isotope dilution using (242)pu spike and mass bias correction using U-233 and U-236 mixed solution enabled the quantification of Pu and measurement of isotope ratio simultaneously. The contribution of U-238 from both spikes and samples was minimized by careful chemical separation and optimization of spike concentration. The (UH)-U-238-H-1 and tail contribution on Pu-239 peak were about 0.75 x 10(-5) and 1 x 10(-5) of U-238 intensity, respectively, and they were corrected from Pu-239 using externally determined ((UH)-U-238-H-1+tailing)/U-238 ratio and U-238 measurement during acquisition. The detection limits of this analytical procedure were 0.61 fg/ml and 0.56 fg/ml for Pu-239 and (240)pu, respectively (4 nBq/m(3) and 12 nBq/m(3) for Pu-239 and Pu-240, respectively). The precision of isotope ratio measurement was better than 2% for larger quantity than 20 fg of Pu-239.