Development of HCl-free solid-phase extraction combined with ICP-MS/MS for rapid assessment of difficult-to-measure radionuclides. Part I. Selective measurement of ⁹³Zr and ⁹³Mo in concrete rubble

A new HCl-free chromatographic separation procedure has been developed for sequential separation of Zr and Mo from concrete matrices for selective measurement of ⁹³Zr and ⁹³Mo by ICP-MS/MS. The recoveries of greater than 90% for Zr and Mo from concretes could be achieved. The measurement condition was optimized for complete suppression of interferences from ⁹³Nb and peak tailing from abundant isotopes of Zr and Mo in concrete matrices. The removal of interferences was verified by measurement of radio-contamination-free concretes used as a sample matrix blank. Method detection limits of 1.7 mBq g^-1 and 0.2 Bq g^-1 were achieved for, respectively, ⁹³Zr and ⁹³Mo in the concrete matrices. The interference removal factor for Nb (equivalent to the decontamination factor in radiochemical separation) was of the order of 10⁵, and the abundance sensitivity was of the order of 10^-8, indicating that the developed method is reliable for verifying the presence of ultralow concentrations of ⁹³Zr and ⁹³Mo. The present method is suitable for the rapid assessment of ⁹³Zr and ⁹³Mo for radioactivity inventory of concrete rubble. (author)