Speciation Analysis of Chromium in Waters

The total content of chromium in natural waters does not generally exceed several μg/l. Thus, it is obvious that various forms of chromium will occur at the levels of tenths or hundredths of μg/l. Their determination requires the application of a sufficiently sensitive method, but its specificity has an important role to play in the case of chemical individuals or selectivity in regard to speciation of a group of compounds, e.g. valency states or organic chromium complexes. Generally, however, there is a lack of specific and selective methods, and the concentrations of various forms of the analyte occur often at the level of detection limits of even such sensitive techniques as atomic absorption spectrometry. This paper presents a review of currently available analytical possibilities of chromium speciation investigations in natural water samples. Analytical procedure schemes enabling "total speciation analysis" have been discussed in some detail. A large group of methods used in the speciation analysis of chromium(III) and chromium(VI), both in off-line and on-line mode, has also been discussed.