Spectrophotometric determination of copper after selective extraction withalpha-(2-benzimidazolyl)-alpha 'alpha ''-(N-5-nitro-2-pyridyl hydrazone)-toluene in the presence of Brij 58

The spectrophotometric determination of Cu(II) with alpha-(2-benzimidazolyl )-alpha',alpha "-(N-5-nitro-2-pyridylhydrazone)-toluene has been investigat ed. The optimum conditions of pH, stability, concentration of ligand and su rfactant were evaluated. This method is a simple and sensitive method for d etermination of Cu(II) and offers a selective separation of Cu(II) from sam ple solution containing 1 ppm below amount of Ni(II), Co(II), Zn(II) and Sn (II). Copper was determined by measuring the absorbance of Cu(II)-BINPHT co mplex extracted with benzene in Brij 58 surfactant at 410 nm. Beer's law is obeyed over the concentration range 0 similar to 2.5 mu gmL(-1) and the de tection limit (S/N=2) is 0.06 mu gmL(-1). The relative standard deviation a t the 0.3 mu gmL(-1) is 2.4% (N=7). The method was applied for the determin ation of Cu(II) in various milks.