金属イオンのテフロンキャピラリーチューブへの吸着現象とその抑制効果を利用するフローインジェクション分析

抄録

The adsorption of metal ions to the inner surface of a Teflon tube was investigated. A Teflon tube is used in flow analysis, such as in the catalytic method and the chemiluminescence method, as a reaction coil and as a means to transport solvents containing analyte, reagents and a pH buffer agent. A Teflon surface obtained by treating with an alkaline solution (2 M NaOH, 3 h) adsorbed metal ions in the flow solution. The species adsorbed on the inner surface of the Teflon tube interfered with the determination owing to an increase in the blank values. The adsorbed species were metal cations in an alkaline solution. The site of adsorption was presumed to be the anion site based on dissociation of the hydroxy group introduced by the substitution of fluorine. Therefore, a method for decreasing the adsorption sites was examined. As a result, the addition of magnesium (II) was effective to decrease the blank values. In the case of a catalytic analysis for manganese (II) with 2-hydroxy-1-(2-hydroxy-4-sulfo-1-naphthylazo-3-naphtoic acid, the reagent blank decreased down to the minimum value upon the addition of magnesium (II). The number of adsorption sites obtained with the determination of fluorine eliminated by an alkaline treatment agrees with the result (3.1×10¹²/cm²) calculated from saturated adsorbents.