Miura Y, Watanabe M
Department of Chemistry, Faculty of Science, Takai University, Hiratsuka, Kanagawa, Japan.
J Chromatogr A. 2001 Jun 22;920(1-2):163-71. doi: 10.1016/s0021-9673(00)01261-9.
The reduction of iodine with azide, catalyzed by polythionates (tri-, tetra-, penta- and hexathionate) and thiosulfate, has been utilized as a postcolumn reaction for chromatographic determination of these sulfur oxyanions. The method is based on the separation of polythionates and thiosulfate on an octadecylsilica column with an acetonitrile-water (20:80, v/v) mobile phase (pH 5.0) containing 3 mM tetrapropylammonium hydroxide and 6 mM acetic acid, followed by photometric measurement of the residual iodine (as triiodide) from the catalytic postcolumn azide-iodine reaction after mixing a reaction solution containing azide and iodine with the column effluent. Chromatograms obtained for the sulfur oxyanions showed negative peaks as a result of the decrease in absorbance of background. The conditions for the catalytic postcolumn reaction of the sulfur oxyanions in the column effluents were established by varying the concentrations of azide, iodine, iodide and acetic acid in the reaction solution, and varying the flow-rate, reaction temperature and length of the reaction tube. The detection limits (defined as SIN = 3) were 4.3 microM for trithionate, 0.10 microM for tetrathionate, 2.7 nM for pentathionate, 5.0 nM for hexathionate and 1.1 nM for thiosulfate. When compared with earlier methods, the proposed method gave a much higher sensitivity for the determination of two polythionates (penta- and hexathionate) and thiosulfate. This method was applied successfully to the analysis of polythionates and thiosulfate added to hot-spring water samples.
连多硫酸盐（三硫代硫酸盐、四硫代硫酸盐、五硫代硫酸盐和六硫代硫酸盐）和硫代硫酸盐催化叠氮化钠还原碘，已被用作柱后反应，用于色谱法测定这些硫氧阴离子。该方法基于在十八烷基硅胶柱上，以含有3 mM四丙基氢氧化铵和6 mM乙酸的乙腈 - 水（20:80，v/v）流动相（pH 5.0）分离连多硫酸盐和硫代硫酸盐，然后将含有叠氮化钠和碘的反应溶液与柱流出物混合后，对柱后催化叠氮化钠 - 碘反应中残留的碘（以三碘化物形式）进行光度测量。由于背景吸光度降低，硫氧阴离子的色谱图显示为负峰。通过改变反应溶液中叠氮化钠、碘、碘化物和乙酸的浓度，以及改变流速、反应温度和反应管长度，确定了柱流出物中硫氧阴离子的柱后催化反应条件。检测限（定义为S/N = 3）对于三硫代硫酸盐为4.3 μM，对于四硫代硫酸盐为0.10 μM，对于五硫代硫酸盐为2.7 nM，对于六硫代硫酸盐为5.0 nM，对于硫代硫酸盐为1.1 nM。与早期方法相比，该方法对两种连多硫酸盐（五硫代硫酸盐和六硫代硫酸盐）和硫代硫酸盐的测定具有更高的灵敏度。该方法已成功应用于温泉水样中添加的连多硫酸盐和硫代硫酸盐的分析。
