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本文对同位素稀释电感耦合等离子体质谱法(ICP—MS)测定硅酸盐岩石中痕量铀和钍的可能性进行了评述。与热电离质谱常规同位素稀释法比较,主要的优点是在精密度和准确度不明显降低的情况下,大大提高了样品的分析速度,其原因是它不需要与基体元素分离,在常压下直接吸取液体样品,测量其原始溶液的同位素比。该方法采用的标准不需与基体严格一致。另外,它对可能引起强度漂移的因素(例如:等离子体与质谱仪界面的阻塞和离子束的散焦)及化学效应(例如:形成氧化物)不大敏感。用几个国际岩矿标准样品考核,所得结果与推荐值一致。
In this paper, the possibility of determining isotopic uranium and thorium in silicate rock by isotope dilution ICP-MS was reviewed. Compared with the conventional isotope dilution method of thermal ionization mass spectrometry, the main advantage is that the sample analysis speed is greatly increased without noticeable decrease in precision and accuracy because it does not need to be separated from the matrix element. Under normal pressure Draw directly on the liquid sample and measure the isotopic ratio of its original solution. The method used in the standard does not need to strictly consistent with the substrate. In addition, it is less sensitive to factors that can cause intensity drift (eg, clogging of the plasma-mass spectrometer interface and defocusing of the ion beam) and chemical effects (eg, formation of oxides). Several international rock and mineral standards with a sample test, the results obtained and the recommended value.