Advances and future trends in radioisotope analysis and applications

Modern advances that facilitate the accurate activity analysis of radionuclides as either single or multiple isotope tracers are described, with a focus on applications in the agricultural and biological sciences. The advances comprise both instrumental design and techniques. These are described in the following topics: (i) liquid scintillation analysis (LSA) via a quench-indicating parameter (QIP), (ii) direct DPM methods, (iii) low-level liquid scintillation analysis, (iv) Cherenkov counting, (v) microplate scintillation analysis, (vi) multiple radionuclide analysis, (vii) solid scintillation analysis, (viii) radionuclide standardization, (ix) instrument performance assessment (IPA), (x) 'Replay', and (xi) flow scintillation analysis (FSA). The use of LSA with a QIP will remain the mainstay analytical technique for years to come. Modern liquid scintillation analysers equipped with bismus germanate detector guards and time-resolved liquid scintillation counting (TR-LSC) permit low-level radioactivity analysis such as that required in 14C dating of soil organic matter and soil water flux studies of environmental 3H. Advances in microplate scintillation analysis permit the efficient activity analysis of alpha-, beta- and weak gamma-emitting radionuclides with high sample throughput (up to over a thousand samples daily) at reduced cost of consumable materials and waste disposal. Advances in radioisotope activity analysis have been focused on computerized and automated instrumentation with high sample throughput, greater detection efficiencies, refined analysis of radionuclide mixtures, and lower backgrounds with concomitant improved lower limits of detection. (author)