Dual-wavelength spectrophotometric simultaneous determination of copper and chromium with sensitizing of microemulsion

In the presence of microemulsion of CTMAB-n-butanol-n-heptane-water, the absorption spectra for the complex both of copper* and chromium* with salicyl fluorone was studied.The amounts of copper and chromium can be found simultaneously by standard-addition method at the appropriate reference wavelength and determination wavelength.The apparent molar absorptivity is e_(562)=1.408×10~5 L·mol~(-1)·cm~(-1) for (Cu* ) and e_(576)=1.66×10~5 L·mol~(-1)·cm~(-1) for Cr* in the medium of KH_2PO_4-K_2HPO_4 buffer solution (pH 6.4) and microemulsion.Compared with that in CTMAB medium,the sensitivities of the color reactions for copper and chromium in the microemulsion medium are increased by 16% and 28% respectively.The proposed method has been successfully applied to the determination of copper and chromium in alloy steel.