Analytical Sciences

A Rapid Enrichment Technique for the Ultratrace Determination of Nickel in Water Samples Using a Nanofiber-composite Membrane Filter

Hitoshi MIZUGUCHI,*1 Ryota ISHIDA,*1 Yasushi KOUNO,*2 Tadahiko TACHIBANA,*2 Tomomi HONDA,*3 Tatsuro KIJIMA,*4 Yuhei YAMAMOTO,*1 and Toshio TAKAYANAGI*1

*1 Graduate School of Science and Technology, Tokushima University, Tokushima 770-8506, Japan
*2 Azumi Filter Paper Co., Ltd., 4-2-15 Komatsu, Higashiyodogawa, Osaka 533-0004, Japan
*3 Department of Mechanical Engineering, Graduate School of Engineering, University of Fukui, Fukui 910-8507, Japan
*4 Graduate School of Science and Engineering, Yamagata University, Yonezawa 992-8510, Japan

A new method for the rapid enrichment and highly sensitive determination of nickel ion has been developed by using a nanofiber-composite membrane filter, which was fabricated by stacking a nanofibrous material made of nylon 6 over a water-permeable membrane filter. The noncharged nickel-α-furil dioxime complex was adsorbed on a nanofibrous layer of the membrane filter under significantly higher flow rates than those used for conventional solid-phase extraction techniques. Highly sensitive determinations with detection limits at sub-parts per billion levels were achieved by enrichment from 50 mL of the complex solution, and the enrichment was completed within 3 min. The color that was developed on the membrane filter was successfully subjected to visual colorimetric analysis and quantitative determination by solid-phase spectrophotometry. In addition, colorimetric determination was feasible with a handheld spectrometer after elution of the colored agent with 50 μL of acetone. This combination of rapid enrichment and spectrometric measurement in a small-volume sample provides a useful analytical method suitable for on-site analysis, which requires neither expensive instruments nor high laboratory skills.

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