Mass spectrometric analysis of long-lived radionuclides in bio-assays

Abstract

During the past few decades releases of man-made radionuclides into the biosphere have created environmental contamination that has provoked public concern. This has also raised the need to accurately and in a timely manner determine the quantities of radionuclides in environmental samples and in bio-assays in order to assess their potential impact on public health. The wide spectrum of emission sources has resulted in heterogeneous structures and different isotopic compositions of the contamination that, in turn, has produced new and very specific elemental and isotopic features. Nowadays, mass spectrometry is increasingly used for the determination of many long-lived radionuclides with low specific activities in environmental and biological samples. In summary, the merits of particular mass spectrometric methods include (i) low detection limits (ICP-MS, TIMS, etc.), (ii) high precision of the measured isotopic ratios (multi-collector ICP-MS and TIMS), (iii) high selectivity and abundance sensitivity (RIMS, AMS), and (iv) possibility for a spatially resolved isotope analysis (SIMS, LA-ICP-MS). Mass spectrometric analysis of long-lived radionuclides has been employed in radiobiology and biomedical studies, environmental monitoring and remediation, climate research, and forensics. The implementation of imaging inorganic mass spectrometry in proteomic research is highly promising for the study of radionuclide speciation mechanisms in organs and tissue on a bio-molecular level. This paper summarises specific features of major radioactive contaminations that have occurred during the last few decades and discusses the merits of modern mass spectrometric techniques, with examples of the determination of long-lived isotopes of actinides and fission products in biological samples.