Synthesis of 1-(4-nitrophenyl)-3-(2-pyrazine)-triazene and its color reaction with cadmium

This paper reports the synthesis of a new reagent 1-(4-nitrophenyl)-3-(2-pyrazine)-triazene and its color reaction with cadmium(Ⅱ).In the presence of the surfactant Triton X-100 and in the medium Na2B4O7-NaOH of pH 10.5,the reagent reacts with cadmium(Ⅱ) to form a 4∶1 yellow-brown complex.The maximum absorption wavelength is at 453 nm.The molar absorptivity is 6.9×104 L·mol-1·cm-1.Beer′s law is obeyed in the range of 0～0.56 μg/mL for cadmium(Ⅱ).The method has been applied to the determination of cadmium(Ⅱ) in waster water samples with satisfactory results.