Very low contents (in the range of 10⁻⁹ g/g) of Ir in mantle-derived rock samples (komatiites) were non-destructively determined by INAA coupled with coincidence gamma-ray spectrometry using 16 Ge detectors. Aliquots of the same samples were analyzed by NiS fire-assay ICP-MS for Ir and other platinum group elements. Because the INAA procedure used in this study is non-destructive and is almost free from spectral interference in gamma-ray spectrometry, the INAA values of Ir contents obtained in this study can be highly reliable. Iridium values obtained by ICP-MS were consistent with the INAA values, implying that the ICP-MS values of Ir obtained in this study are equally reliable. Under the present experimental conditions, detection limits were estimated to be 1 pg/g, which corresponds to 0.1 pg for a sample mass of 0.1 g. These levels can be even lowered by an order of magnitude, if necessary, which cannot be achieved by ICP-MS carried out in this study.

含量极低（在 10 ^-9范围内 通过 INAA 结合使用 16 Ge 探测器的符合伽马射线光谱法，非破坏性地测定了地幔衍生岩石样品（科马提岩）中的 Ir 的 g/g）。用 NiS 火焰分析 ICP-MS 对相同样品的等分试样进行 Ir 和其他铂族元素的分析。由于本研究中使用的 INAA 程序是非破坏性的，并且在伽马射线光谱中几乎不受光谱干扰，因此本研究中获得的 Ir 含量的 INAA 值具有很高的可靠性。ICP-MS得到的铱值与INAA值一致，说明本研究得到的Ir的ICP-MS值同样可靠。在目前的实验条件下，检测限估计为 1 pg/g，对应于 0.1 pg 的样品质量为 0.1 g。这些水平甚至可以降低一个数量级，