An eco-friendly, sensitive and selective derivative spectrophotometric method for simultaneous determination of copper and zinc in synthetic mixtures, alloys and environmental samples

This article proposes a cost-effective and green sensitive derivative spectrophotometric method for simultaneous determination of two essential elements, copper and zinc as their complexes with 2-(5-Bromo-2-pyridylazo)-5-diethyl-aminophenol in presence of a cationic micellar medium. The analytical sensitivity and molar absorption coefficient of the 1 : 2 Cu(II)-5-Br-PADAP complex in cationic micellar media are 1.30 x 10(-2) ng mL(-1) and 1.10 x 10(5) L mol(-1) cm(-1), respectively. Beer's law is obeyed in the concentration range from 3.20 x 10(-2) to 8.32 x 10(-1) mu g mL(-1) and the limit of detection of Cu(II) is 3.80 x 10(-2) ng mL(-1). The satisfactory results are obtained for the determination of Cu(II) in derivative modes, with a relative standard deviation of 1.44% (n = 6). In normal mode, the determination of Cu(II) and Zn(II) in presence of each other is difficult because of their overlapping absorption spectral profiles. In second-order derivative mode, 1.28 x 10(-1) - 8.32 x 10(-1) mu g mL(-1) of Cu(II) and 6.50 x 10(-2) - 6.50 x 10(-1) mu g mL(-1) of Zn(II) can be simultaneously determined at zero cross-over point of Zn(II) and Cu(II) complexes, respectively, when present together without any prior time consuming extraction/separation steps using toxic organic solvents. The proposed rapid and selective derivative spectrophotometric method has been successfully assessed for simultaneous determination of copper and zinc in synthetic mixtures, alloys, and environmental samples.