Nair A G C, Acharya R, Sudarshan K, Gangotra S, Reddy A V R, Manohar S B, Goswami A
Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.
Anal Chem. 2003 Sep 15;75(18):4868-74. doi: 10.1021/ac034457d.
A k0-based internal monostandard instrumental neutron activation analysis method for determination of relative elemental concentration in samples of large size and irregular geometry has been developed. In this method, one of the elements present in the sample is used as comparator. A priori knowledge of the concentration of one of the constituents is required to convert the relative concentration into absolute values. The problems of gamma-ray self-attenuation and geometrical effects that arise in the assay of large and nonstandard geometry samples were overcome by an in situ relative detection efficiency calibration procedure, which requires one or more activation products emitting gamma-rays over a wide range of the spectrum. To minimize the problem of neutron flux perturbations that may arise in large samples, irradiations were carried out using a thermal column with thermal neutron component of more than 99.9%. The method has been standardized with samples of silica (approximately 0.5 kg) and water (0.5 L) spiked with known amounts of different elements and has been advantageously applied to some alloy and metal samples of irregular geometry, where complete compositional characterization was carried out using mass balance. This approach is highly valuable for analysis of large, irregularly shaped samples if not too high demands are set to the degree of accuracy.
已开发出一种基于k0的内标法仪器中子活化分析方法，用于测定大尺寸和不规则几何形状样品中的相对元素浓度。在该方法中，样品中存在的一种元素用作比较剂。需要一种成分浓度的先验知识才能将相对浓度转换为绝对值。通过原位相对探测效率校准程序克服了大尺寸和非标准几何形状样品分析中出现的伽马射线自吸收和几何效应问题，该校准程序需要一种或多种在宽光谱范围内发射伽马射线的活化产物。为了尽量减少大样品中可能出现的中子通量扰动问题，使用热中子成分超过99.9%的热柱进行辐照。该方法已用掺有已知量不同元素的二氧化硅样品（约0.5 kg）和水（0.5 L）进行了标准化，并已成功应用于一些不规则几何形状的合金和金属样品，在这些样品中使用质量平衡进行了完整的成分表征。如果对准确度要求不太高，这种方法对于分析大的、形状不规则的样品非常有价值。
