[Simultaneous determination of copper(II) and chromium(III) by absorbance ratio-derivative method]

In the present paper, an absorbance ratio-derivative method for the simultaneous determination of copper(II) and chromium(III) was proposed. In the HAc-NaAc buffer solution at pH 5.7 with heating, Cr3+ or Cu2+ with CAS and CTMAB formed a blue ternary complex. The molar absorptivities of Cr(III)-CAS-CTMAB and Cu(II)-CAS-CTMAB were 2.52 x 10(5) L x mol(-1) x cm(-1) and 1.01 x 10(5) L x mol(-1) x cm(-1) respectively. Beer's law was obeyed in the range of 0. 08-1.2 microg x mL(-1) for Cu (II) and 0.05-0.52 microg x mL(-1) for Cr(III). The detection limits of Cu(II) and Cr(III) are 0.014 microg x mL(-1) and 0.013 microg x mL(-1) respectively. This method was applied to the determination of Cu(II) and Cr(III) in surrounding water with satisfactory results.