Composition-ratio determination of Chrome Azurol S (CAS) with Cu(2+) and research on dynamic reaction process of CAS with EDTA.

The composition-ratio of Chrome Azurol S (CAS) with Cu(2+) and dynamic reaction process of CAS with EDTA were studied by spectrophotometry. The composition-ratio of Cu(2+) with CAS (2:1) was successfully determined using the method of lines and EDTA complexing substitution. The effects of temperature, time, pH, concentration of cetyltrimethylammonium bromide (CTMAB), and concentration of Cu(2+) on the absorption spectrum were also discussed. By optimizing experimental conditions, the dynamic process of displacement of CAS, which forms the ternary compound Cu-CAS-CTMAB, by EDTA were determined. The test results indicated that EDTA can replace 99.6% of the CAS quickly when heated. The system reached equilibrium finally. This research method can be applied to the qualitative and quantitative analysis of related Cu complexes.