小型全反射蛍光X線分析装置を用いた微量カドミウム分析

摘要

Nanograms of Cd are measured with a portable total reflection X-ray fluorescence spectrometer. A relationship between a detection limit for Cd and counting time is investigated. A Cd detection limit is improved with the increase in counting time, and a detection limit of 1 ng is achieved when a measurement is performed for 1800 s. Cadmium quantitative performance is shown. Yttrium is used as an internal standard element, and the Cd Ka/Y Ka intensity ratio is linear with mass of Cd in the range from 10 to lOlOng. Detection limits for Cd obtained with or without a 30 μm thick Mo absorber are compared. The spectral background is reduced using the Mo absorber, leading to an increase in the signal to background ratio of the Cd Ka line. However, the use of the Mo absorber results in a decrease in the net intensity of the Cd Ka line. Therefore, a detection limit obtained with the Mo absorber is as low as that obtained without an absorber.%全反射蛍光Ⅹ線分析法は，微少試料に極微量含まれる元素の分析を可能にする。原子吸光分析法（AAS），誘導結合プラズマ質量分析法（ICP－MS）や誘導結合プラズマ発光分析法（ICP－AES）と同様の試料調製により測定を行うことができるが，溶液分析に際して必要な試料量は〃L量である。また，固体試料の酸分解など試料調製に要する試薬も少なくすることが可能なので，環境にやさしい分析法であるといえる。全反射蛍光Ⅹ線分析では，高強度Ⅹ線源の使用が高感度分析を行うために必要不可欠とされ，大型シンクロトロン放射光施設を利用することで，3d遷移金属元素においてフェムトグラム（10~(-15)g）量の検出下限が達成された。