Analytical Sciences

An Improved Reflection Colorimeter Integrated with a Coaxial Optical-fiber Cable for Highly Sensitive Solid-phase Colorimetry Using a Membrane Filter

Hitoshi MIZUGUCHI,*1 Yusuke TANIGUCHI,*1 Suherman SUHERMAN,*2 Kinichi MORITA,*3 Toshio TAKAYANAGI,*1 and Yasutada SUZUKI*4

*1 Department of Applied Chemistry, Graduate School of Science and Technology, Tokushima University, Tokushima 770-8506, Japan
*2 Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia
*3 Ushio Inc., 1-6-5 Marunouchi, Chiyoda, Tokyo 100-8150, Japan
*4 College of Bioscience and Chemistry, Kanazawa Institute of Technology, 3-1 Yatsukaho, Hakusan, Ishikawa 924-0838, Japan

Highly sensitive solid-phase colorimetry for nickel ion was demonstrated using an improved reflection colorimeter equipped with a coaxial optical-fiber cable. The nickel complex with α-furil dioxime was collected on a small-size membrane filter embedded in a disposable syringe filter unit. The leading edge of the optical-fiber cable was connected to the syringe filter unit via a Luer-lock fitting, and the color intensity of the sample on the filter was evaluated accurately. The detection limit was 0.8 ng in 2.5 mL of the complex solution (0.3 μg L⁻¹). This improved configuration is applicable to highly sensitive on-site analysis without expensive instruments nor high laboratory skills.

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