Speciation of metals associated with natural water components by on-line membrane fractionation combined with inductively coupled plasma atomic emission and mass spectrometries

Specially designed multistage membrane filtration devices for the size fractionation of suspended particles and solutes were tested and used for speciation studies of metals associated with natural water components. The separated fractions were adapted to analysis by plasma source atomic emission and mass spectrometry. The distribution patterns for Al, Fe, Zn, Mn, Ni, Co, as well as Na, K, Mg, Ca in samples of river waters in Saxony were studied. Alkali and alkaline earth metals are distributed evenly between the fractions whereas easily hydrolysed trace elements mainly remain in the fraction containing the largest amounts of paniculate matter. The distribution of the analytes between the different fractions is influenced by both the storage time of the solution before fractionation and the addition of acids to stabilise the aqueous samples during storage.