A FLOW-INJECTION/XPS INVESTIGATION OF THE EFFECT OF REDOX EQUILIBRIA ON THE SELECTIVITY OF AN IODIDE-SELECTIVE ELECTRODE

被引：27

作者：

DAVEY, DE ^{[1
]}

MULCAHY, DE ^{[1
]}

OCONNELL, GR ^{[1
]}

SMART, RS ^{[1
]}

机构：

[1] UNIV S AUSTRALIA,SCH CHEM TECHNOL,THE LEVELS,SA 5095,AUSTRALIA

来源：

ELECTROANALYSIS | 1995年 / 7卷 / 05期

关键词：

IODIDE-SELECTIVE ELECTRODE; SELECTIVITY COEFFICIENTS; X-RAY PHOTOELECTRON SPECTROSCOPY; POTENTIOMETRY;

D O I：

10.1002/elan.1140070510

中图分类号：

O65 [分析化学];

学科分类号：

070302 ; 081704 ;

摘要：

Flow-injection selectivity coefficients fbr a solid-state iodide-selective electrode were determined for three moderately interfering species-bromide, thiocyanate and thiosulfate-by injecting mixed iodide-interferent solutions into selected reagent streams. The use of neutral and acidified iodate and bromate oxidant streams was found to increase the selectivity of the iodide electrode towards the three interferents. The acidified streams also visibly modified the surface of the electrode membrane, although the resultant coating, ascribed to the formation of elemental sulfur and iodine, was easily removed by manual polishing with slurried alumina and a lint-free cloth. X-ray photoelectron spectroscopy (XPS) performed on pressed AgI/Ag2S pellets following immersion in the acidified iodate and bromate solutions revealed substantial surface modification, with the formation of AgIO3 and AgBr, respectively. Use of ascorbic acid or metabisulfite reducing streams resulted in higher selectivity towards iodide than that obtained using either of the neutral oxidant streams, but less than that obtained in the presence of a simple nitrate reagent stream. In contrast, the use of a thiosulfate stream irreparably damaged the surface of the Electrode to the point where subsequent flow-injection experiments showed excessive peak broadening and very poor baseline recovery. XPS studies performed on the damaged membrane revealed a surface dominated by hydroxides and almost totally devoid of either AgI or Ag2S.

引用

页码：461 / 470

页数：10

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