Determination of Pu isotope concentrations and isotope ratio by inductively coupled plasma mass spectrometry: a review of analytical methodology

A number of analytical methods for Pu isotopes based on ICP-MS measurement have been developed and applied to the measurement of ultra-trace levels of Pu in nuclear fuel samples and environmental samples. The endeavour to improve the detection limit to sub-10(-18) g (ag) mL(-1) has been continued by using efficient sample introduction systems. This review summarizes and critically discusses various types of ICP-MS, sample introduction systems and separation methods applied to the determination of Pu in many sample types. Together with the separation method, the adjustment of the Pu oxidation state in the loading solution preparation step and Pu elution step is summarized. The interference problem from polyatomic ions in ICP-MS coupled with various sample introduction systems is described, especially focused on the UH+ interference. Several factors affecting the trueness and precision of Pu results are discussed.