Speciation of arsenic compounds in natural water
In natural water (groundwater, drinking water and soil pore water) different arsenic compounds like arsenite, arsenate, mono- and dimethylarsinic acids are found depending on conditions like bacterial activity, Eh, and pH. These compounds are characterised by different toxicology, solubility and the adsorption on solid phases. The following arsenic compounds are found in natural water:
H3AsO3 H3AsO4 (CH3)AsO(OH)2 (CH3)2AsO(OH)
To determine the different species in water samples anion- exchange HPLC was combined with hydride- generation atomic absorption spectrometry for the routine speciation of the compounds listed above .
The sensitivity of the used detection system was increased by a post- column reaction system, to achieve a complete formation of volatile arsines from all separated species. Detection limits of all arsenic compounds range between 0.5 and 1.0 µg/l without pre-concentration.