RADIONUCLIDE BIOASSAY BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY (ICP/MS)

Inductively coupled plasma mass spectrometry (ICP/MS) is a sensitive, efficient, and versatile means of elemental analysis that is becoming an acceptable method for measuring long-lived radionuclides in various media. As with other spectrometric techniques, ICP/MS detects atoms rather than the radioactive emissions associated with radionuclides. Thus, it is not limited by the decay characteristics of radioactive materials (e.g. low specific activity). The feasibility of using ICP/MS has been investigated as an alternative method for measuring selected radionuclides (Np-237 and Pu-239) in urine. When used in conjunction with the described separation procedures, ICP/MS provides detection limits similar to or lower than those provided by conventional alpha spectrometry. In addition, the time required to determine the amount of a radionuclide in a sample is short compared with that for alpha particle counting. Continuing research on instrument design and sample-introduction techniques shows promise for further reducing detection limits, while ameliorating, or even eliminating, some of the current limitations of this technique.