Long-term monitoring of arsenic and selenium species in contaminated groundwaters by HPLC and HG-AAS.

The long-term concentration and distribution of species of arsenic and selenium in contaminated groundwaters from Kelheim was monitored. Most of the groundwater wells contained elevated concentrations of iron, manganese and sulfur. Arsenic (III), arsenic (V), selenium (IV) and selenium (VI) were separated using high performance liquid chromatography (HPLC) based on phosphate buffers and collected in fractions. Due to the complex matrix, the fractions were analyzed element-specifically by hydride-generating atomic absorption spectrometry (HG-AAS). The combination of HPLC and HG-AAS was selected due to the authors' intention of developing an easy-to-handle, but nonetheless reliable, method suitable for the long-term monitoring of species distribution in an almost routine way, and taking account of the threshold values of 10 microg/l for each element, indicated by German drinking water regulations. To enhance the reliability of the method, analytical quality control experiments were carried out. When applied to groundwater wells from Kelheim (Germany) they revealed that arsenic (V) and selenium (VI) were the dominating species. The presence of arsenic (III) and selenium (IV) was assumed to be supported by organic matter.