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Determining trace levels of uranium in drinking and mineral water by inductively coupled plasma mass spectroscopy (ICP-MS) requires expensive analytical instrumentation. In contrast, adsorptive cathodic stripping voltammetry (AdCSV) using Metrohm’s 797 VA Computrace is a straightforward, much less expensive alternative allowing measurements with superior sensitivity.

Uranium is radioactive, toxic and a suspected teratogen. While different national health authorities prescribe limits in drinking water ranging from 0 up to 10 µg/L, the World Health Organization (WHO) recommends a concentration limit of 15 µg/L.

The AdCSV method for the voltammetric determination of the uranium content is based on complexing U(VI) with chloranilic acid (CAA) at a pH between 1.8 and 2.5. After preconcentration of the uranium-chloranilic acid complex at the working electrode, the uranium content can be determined down to the ng/L range by using the differential pulse measuring technique (DP). The determination of uranium(VI) is specific and selective, as the positive deposition potential means that other metal-CAA complexes or organic matrix components of natural waters are either not adsorbed on the working electrode or hardly adsorbed at all.

The German standard DIN 38406-17 is currently being drawn up based on this AdCSV method. This means that in future the voltammetric determination of uranium can be used as a generally recognized method for monitoring drinking and mineral water in daily practice.

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