Compact IC with post column reactor

Trace level determination of bromate in drinking and mineral water using Ion Chromatography.

Trace level determination of bromate in drinking and mineral water using Ion Chromatography (IC).

Ozone is widely applied in drinking water processing as a disinfectant and for the oxidation of organic micropollutants.

Spring water always contains some bromide.

As a by-product of bromide oxidation in the water disinfection process, bromate ions are formed.

Due to the potentially carcinogenic nature of bromate, bromate levels in drinking and mineral water have to be monitored.

The German regulations concerning drinking water prescribe a temporary limit of 25 ug/L, other countries already prescribe lower limits.

The processing of mineral waters suffers from similar problems.

Here, the pertinent regulations in Germany, dating from 1st July 2004, prescribe a limit of 3 ug/L.

Bromate analysis by Ion Chromatography The IC/MS method yields the lowest detection limit, the second best is ion chromatography followed by post-column derivatization with iodide (in a post-column reactor = PCR) followed in turn by UV detection.

The analysis can be reliably and accurately performed with Metrohm's economical 844 Compact UV/VIS ion chromatograph (IC), which optionally contains a built-in PCR.

The 844 UV/VIS Compact IC with post column reactor Compact ion chromatograph for the photometric determination of anions and cations in the UV/VIS range.

Very compact construction.

System with integrated dual-piston high-pressure pump, electrically operated injection valve and highly sensitive three-wavelength diode-array detector.

With additional PCR (Post-Column Reactor) and two-channel peristaltic pump.

The analysis is based on the Environmental Protection Agency EPA method 325.0.

In this post-column derivatization method, bromate - aided by the catalytic effect of ammonium molybdate - oxidizes iodide to tri-iodide in an acidic medium.

The tri-iodide absorption is monitored at 352 nm and allows for the calculation of the bromate concentration (so-called indirect detection technique).

As bromate is essentially needed for the oxidation of iodide, the method described here is limited to the determination of bromate; any additional water constituents have to be determined separately.

As a column with a very high capacity is used, the injected volume can be increased to 1 mL.

This results in a significant increase of the sensitivity and allows to determine bromate in the medium ppt range.

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