Simultaneous Determination of Cr(III) and Cr(VI) in Ground and Drinking Waters by IC-ICP-MS

The coupling of ion chromatography (IC) and inductively-coupled plasma mass spectrometry (ICP-MS) provides a powerful tool for the simultaneous determination of Cr(III) and Cr(VI) in water samples. The experimental set-up of the technique is described in detail and performance data are given, whereby detection limits of 0.1 μg/l could be achieved for both chromium species without pre-concentration. With this method, a complete analysis can be done in less than 3 minutes. In order to improve the repeatability of the method, Rh(III) as internal standard is used. Stability of the two chromium species in water turned out to be a major problem and optimal conditions for storage were determined. For real water samples storage at 4 °C in the dark at neutral pH and analysis as fast as possible is recommended. The application of the IC-ICP-MS technique to real water samples and the comparison to another, more time-demanding and less sensitive method proves the capacity of the method.