分析化学
Print ISSN : 0525-1931
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アニオン性色素及び塩基性イオン交換体ナノ粒子からなるナノ薄膜試験紙の作製と評価
高橋 由紀子
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ジャーナル フリー

2014 年 63 巻 6 号 p. 525-531

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In recent years, we have produced next-generation highly sensitive test papers named ‘dye nanoparticle-coated test strips (DNTSs)’ for harmful ions at ppb level in aqueous samples. The preparative method based on re-precipitation method is simple and feasible, but applicable indicator dyes are limited to be hydrophobic one. In order to fabricate DNTSs with hydrophilic charged indicators, we here report a novel method to prepare DNTSs loaded nano-composites of anionic dyes and ion exchange nano-adsorbents. We tested four popular anionic reagents (tetra-sulfonated TPPS; tri-sulfonated HNB; di-sulfonated Bathophen-S; mono-sulfonated Lumogallion) and two ion exchange nano-adsorbents [weakly basic alumina fiber, AS3 (10 nm×100 nm) and strongly basic trimethyl-modified latex, latex-N(CH3)3+ (100 nm in diameter)]. The preparative method of nano-composite coated DNTSs is also simple; initially an anionic indicator and a nano-adsorbent are mixed in pH-controlled water, and then the dispersion is filtered with a membrane filter having a 0.1 μm pore size under suction. The retained reagent percentage on the membrane strongly depends on ion exchange nano-adsorbent, the charge of an anionic dye, and the reagent concentration, because the nano-composite formation is based on electrostatic interaction. Especially, by using latex-N(CH3)3+, almost 100% coating of anionic dyes was successful in the pH range of 2 – 10. Particle size analysis and zeta potential measurements indicated that nano-composite layers are made in two ways: one is surface filtration of the reagent-adsorbed ion-exchanger; the other is filtration of aggregates of reagent-adsorbed ion-exchangers. The thickness of the nano-composites layer depended on the surface concentration of nano-adsorbent as well as the zeta potential of the nano-composite. The thicknesses of nano-composite layers were 4.55 μm for TPPS/latex-N(CH3)3+ and 3.34 μm for TPPS/AS3 when the surface concentrations of nano-adsorbents were adjusted to be 0.26 mg cm−2 and 0.32 mg cm−2, respectively. Highly negatively charged dyes, like TPPS and HNB, are applicable to the detection of metal ion by filtration enrichment of a sample solution containing high concentration of NaCl; however, mono-anionic or di-anionic dyes, such as Lumogallion and Bathophen-S, are inapplicable due to the leakage of dye or signaling complexes with target ions.

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© The Japan Society for Analytical Chemistry 2014
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