Many rock formations contain small amounts of uranium minerals. Weathering processes release uranium into the soil, water and atmosphere. Because of its subchronic toxicity, the introduction of a limit for the uranium content of drinking and mineral water has been demanded for some time. In the European Union the corresponding limits have not yet been fixed by law. Internationally, the stipulated limiting values range from 10 to 30 µg/L uranium.
The accurate quantification of trace amounts of uranium generally requires complicated and expensive analytical equipment such as instruments based on inductively coupled professional plasma mass spectrometry (ICP-MS). In contrast, with the Metrohm 797 VA Computrace, dissolved uranium in the form of U(VI) can be determined easily and at reasonable expenditure! The voltammetric determination of uranium with the 797 VA Computrace is just as accurate and efficient as current ICP-MS methods.
The AdCSV method (Adsorptive Cathodic Stripping Voltammetry) for the voltammetric determination of the uranium content is based on complexing U(VI) with chloranilic acid (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone). The uranium content can be determined down to the ng/L range.
DIN Standard 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.