Lanthanide isotopic analysis

There are three general motivations for analysis of natural samples (1) exploration for rare-earth mineral resources, (2) isotopic analysis for elucidation of the geological history of the earth, and (3) analysis of living samples to investigate natural distribution of lanthanides in the biosphere. The analysis of geologic samples for rare-earth content has obvious implications for rare-earth mining, and rare-earth analyses also have been... 

G. S. Schuhmann and J.A. Philpotts, Mass-spectrometric stable-isotope dilution analysis for lanthanides in geochemical materials 471... 

A full account of the problems considered in collecting, storing, and processing marine samples for transuranic analysis is given in the above-mentioned review (4). The specific methods discussed here were foimd effective at least for the transuranic analyses of seawater and sediments contaminated by global fallout, nuclear fuel reprocessing wastes, or nuclear power plant operation waste. In these cases, a preliminary acid treatment of the sample in the presence of suitable yield monitors seems to solubilize the transuranic elements and achieves isotopic equilibration between the yield monitor and sample. The yield monitors used were either Pu or sep qj. 238,239,240,24ip whereas Am was used for Am, 2 Cm, and by inference, Cf. In addition, it was convenient to use 50 mg of a lanthanide (neodymium) as a carrier for americium to purify the separated americium fraction. 

Applications of ICP-MS cover a wide range of sample types which often make use of its excellent sensitivity and isotope ratio capabilities, such as the determination of ultra-low levels of impurities in semiconductors, long-lived radionuclides in the environment, and geochronology. ICP-MS is well suited to the determination of the lanthanide series of elements in many geological applications. Sample preparation methods are similar to those generally used for trace metals analysis however, nitric acid is favored for sample digestion because other mineral acids contain elements which cause spectroscopic in-teferences. 

Because of the high radiotoxicity of most of the actinide nuclides, only very limited studies of the biokinetics of plutonium and other important actinides are possible in human volunteers. As our information about the long-term retention of actinides is limited, there is interest in the possible use of stable lanthanide elements as surrogates for the actinides for long-term biokinetic studies in humans. The aim of such studies is to inject appropriate stable isotopes of lanthanides such as cerium, europium, and gadolinium into human volunteers and then to measure the excretion of the lanthanide in urine and faeces by mass spectrometry, charged-particle activation analysis or similar methods. Also, limited human studies can also be carried out using small doses of appropriate lanthanide radionuclides (Bailey 1989). 

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