Analytical Sciences

Grazing-Exit and Micro X-ray Fluorescence Analyses for Chemical Microchips

Kouichi TSUJI,*^1,*² Tetsuya EMOTO,*¹ Yosuke NISHIDA,*¹ Eiichiro TAMAKI,*³ Yoshikuni KIKUTANI,*⁴ Akihide HIBARA,*^2,*³ and Takehiko KITAMORI*^3,*⁴

*1 Department of Applied Chemistry, Graduate School of Engineering, Osaka City University (OCU), Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, Japan
*2 JST-PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
*3 Department of Applied Chemistry, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
*4 Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakato, Takatsu, Kawasaki 213-0012, Japan

Grazing-exit x-ray fluorescence (GE-XRF) and micro x-ray fluorescence (μ-XRF) methods were applied to chemical microchips as a detection method. Since an energy-dispersive x-ray detector was used, the simultaneous detection of multiple elements was possible. An analyzing region was especially designed on the microchip so that a sample solution could be dried and concentrated in a suitable area corresponding to the size of the primary x-ray beam. Finally, it was confirmed that both analytical methods could be combined well for use with a microchip. In GE-XRF, the background intensity in the XRF spectrum was reduced at grazing-exit angles. In addition, a good relationship between the x-ray fluorescence intensities and the concentrations of standard solutions that were introduced into the microchip was obtained. This indicates that the GE-XRF method is feasible for trace elemental analysis in chemical microchip systems. In μ-XRF, an attempt was made to concentrate and dry the analyte within a small analyzing region. The preliminary results indicated that the μ-XRF method could be applied for the analysis of microchips.

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