L殻選択励起法による米中カドミウムの蛍光X線微量分析

Trace Analysis of Cadmium in Rice by the Selective Excitation of L-Shell X-ray Fluorescence

Sugihara Yuko

Hayakawa Shinjiro

Namatame Hirofumi

Hirokawa Takeshi

分析化学

米中のカドミウムについてCd-Lα線を用いる蛍光X線分析の最適化を行った.米中に多量に含まれるカリウムのKα線による妨害を防ぐため,K吸収端下の励起条件を用いて,カドミウムの選択励起を行った.選択励起法によりカリウム由来のバックグラウンドは大きく低減することができるが,非弾性共鳴散乱(RIXS)によるバックグラウンドが検出限界を支配していることが明らかになった.最適な励起X線エネルギーの検討を行った結果,3580 eV励起で最適化された.さらに,試料の保持方法についても検討を行い,6 μm厚のポリプロピレン膜上に米粉末を固定化する方法によりバックグラウンドを低減した.最適条件での米中カドミウムの検出限界として0.34 ppmを実現した.

The trace analysis of cadmium in rice was carried out by using L-shell excitation of X-ray fluorescence analysis. To reduce the influence of co-existing potassium, the excitation X-ray energy was selected below the absorption edge of potassium. It was found that the remaining background was from resonant inelastic X-ray scattering (RIXS) from potassium. The excitation X-ray energy dependence of the RIXS spectra from KCl was measured, and the optimized X-ray energy was 3580 eV. Optimization of the sample support was also investigated, and the rice flour was fixed onto a film of 6 μm thick polypropylene with polyvinyl acetate. The detection limit of cadmium in rice was 0.34 ppm under the optimized condition.

cadmium

L-shell

X-ray fluorescence analysis

trace analysis

resonant inelastic X-ray scattering

Chemistry [ 430 ]

jpn

日本分析化学会

(c) 2011 The Japan Society for Analytical Chemistry

[ISSN] 0525-1931

[DOI] 10.2116/bunsekikagaku.60.613

[NCID] AN00222633

[DOI] http://dx.doi.org/10.2116/bunsekikagaku.60.613