APPLICATION OF A HIGH-RESOLUTION INDUCTIVELY COUPLED PLASMA MASS-SPECTROMETER TO THE MEASUREMENT OF LONG-LIVED RADIONUCLIDES

Some long-lived radionuclides, such as Tc-99, Ra-226, Th-232, Np-237, U-238, Pu-239 and Pu-240 were measured using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). By using HR-ICP-MS with an ultrasonic nebulizer, the detection limits of these nuclides were 0.002-0.02 pg ml-1 and the sensitivities were 10 times better than those obtained using HR-ICP-MS without the ultrasonic nebulizer. More accurate isotopic data were also obtained using HR-ICP-MS than with quadrupole ICP-MS at lower concentrations of the analyte because of the improvement in counting statistics that can be obtained with HR-ICP-MS due to the greater efficiency of ion transmission. A comparison of the measurement of the Pu-240 to Pu-239 ratio is shown.