Problems of the speciation of chromium in soil samples

Different separation/detection methods (ion exchange, organic extraction, spectrophotometry) and four extraction media have been compared for the speciation of chromium. Due to the pH dependence of these methods only the spectrophotometric method using the diphenylcarbazide reaction has proved suitable for speciation analyses. If nitric acid is used for the initial extraction stage, problems are often encountered with the other method during subsequent speciation analysis. The reasons for this are discussed.