Feasibility study of solid sampling electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of particulate uranium in swipe samples from nuclear facilities

The feasibility of a solid sampling electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) for "the particle analysis of safeguards environmental swipe samples" was studied with polycarbonate (PC) film samples containing thallium (Tl), lead (Pb) and uranium (U) particles in single element and with their solution sample. The influences of instrumental operating conditions on analytical results, especially accuracy and precision in isotope ratio measurements, were investigated. Isotope ratios obtained for Tl and Pb solution samples containing a few picogram amounts of particles were in good agreement with the reference values obtained using pneumatic nebulizer ICP-MS. It is revealed that when vaporization temperature was set to be optimal, the pyrolysis temperatures in the temperature range of this study did not affect the magnitude of integrated signals. Isotope ratios obtained for PC film samples including a few picogram amounts of particles were comparable to those of solution samples, and good values of isotope ratio were obtained in the wide range of measurement parameters even though analyte losses occurred in inappropriate temperature conditions. The pyrolysis and vaporization temperature dependence of the integrated signal was different from those of the solution sample, which is ascribed to the difference of transport efficiency of the vaporized analyte in both samples. Absolute limit of detection for PC film sample was found to be about 2 fg, which corresponds to 2 pg/g for a typical sample mass of 1 mg.