Applikationer

UV/VIS detection is one of the most sensitive detection techniques in trace-level chromatography. Sometimes, however, spectrophotometric detection lacks sensitivity, selectivity or reproducibility and chemical derivatizations are required. By using Metrohm`s rugged and versatile flow-through reactor, single- or multi-step derivatizations can be done fully automatically, in either pre- or post-column mode at any temperature between 25…120 °C. The variable reactor geometry allows to adjust the reactor residence time of the reactants according to derivatization kinetics. The flexibility of the reactor is demonstrated by optimizing four widespread post-column techniques: the relatively slow ninhydrin reaction with amino acids and the fast derivatizations of silicate, bromate and chromate(VI).

This poster discusses results showing the influence of pH, temperature of the post-column reactor, eluent composition, and iodide concentration on the sensitivity of the triiodide method.

Drinking water which has been disinfected via the ozonation process can contain undesirable levels of bromate, a carcinogen, via oxidation of bromide in the raw water. Already several agencies including the World Health Organization have recommended concentration limits for bromate set in place to limit its risks to our health. Ion chromatography is mentioned in several analytical standards for the determination of disinfection byproducts (DBP) including bromate, such as EPA 300.1, 317.0, 321.8, 326.0, ASTM D6581, ISO 11206, and ISO 15061. Monitoring trace levels of bromate online means higher throughput and less time spent performing manual laboratory tests, and ensures quality drinking water is produced.

Bromate is a disinfection byproduct generated by ozonation during drinking water purification. It is undesirable, because it is a suspected human carcinogen. Water suppliers as well as manufacturers of bottled and mineral water need to comply with the limit values set by the respective public authority. The World Health Organization (WHO) sets the maximum contamination level for public water systems at 10 μg/L. In Europe the maximum acceptable concentration of bromate in mineral waters is set to 3 μg/L. Further lowering of these values are under discussion. ISO 11206 describes the determination of bromate in drinking water by IC with UV detection after post-column reaction. Bromate oxidizes iodide in acid solution to iodine. The excess iodide forms with the iodine the triiodide ion (I3-), which absorbs at 352 nm. The present application allows quantification of bromate down to 1 μg/L and below.