Speciation of heavy metals in environmental water by ion chromatography coupled to ICP–MS

Biogenic (e.g. phytochelatins, porphyrins, DOM) as well as anthropogenic (e.g. NTA, EDTA, phosphonates) chelators affect the mobility and cycling of heavy metals in environmental waters. Since such chelators can form strongly bound anionic heavy metal complexes that are stable and highly mobile, anion-exchange chromatography coupled to ICP–MS was investigated. A narrow bore HPLC system was connected to a micro concentric nebuliser for in-line sample introduction. A new chromatographic procedure based on a synthetic hydrophilic quaternary ammonium anion exchanger in combination with nitrate as a strong eluent anion, and gradient elution, provided high separation selectivity and a large analytical window. Low detection limits (nmol L–1) were achieved by on-column matrix removal and sample preconcentration. This allowed the method to be successfully applied to different environmental research areas. In ecotoxicological studies of heavy metal effects on algae low concentrations of metal EDTA complexes were determined in nutrient solutions without interference from high (buffer) salt concentrations. In groundwater, infiltrated by a polluted river, mobile metal EDTA species were observed. In river water of different pollution levels beside CuEDTA other anionic Cu-complexes were found in nmol L–1 concentrations.