Composition-ratio determination of Chrome Azurol S (CAS) with Cu2+ and research on dynamic reaction process of CAS with EDTA

The composition-ratio of Chrome Azurol S (CAS) with Cu2+ and dynamic reaction process of CAS with EDTA were studied by spectrophotometry. The composition-ratio of Cu2+ 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 Cu2+ 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.