4-(4'-Nitrobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole, A new chromogenic reagent for extractive spectrophotometric determination of copper (II) in Pharmaceutical and alloy samples

A simple, selective and rapid extractive spectrophotometric method has been developed for the extraction and determination of Cu (II) with 4-(4'-nitrobenzylidene imino)-3-methyl-5-mercapto-1, 2, 4-triazole, (NBIMMT). The reagent (NBIMMT) instantly forms stable orange-red coloured complex with Cu (II) at room temperature and quantitatively extracted in chloroform at pH 6.2. The extracted species exhibits absorption maximum at 470 nm against reagent blank. The Beer's law was followed in concentration range 4.75 to 16.13 ppm of Cu (II) and optimum concentration range obtained from Ringbom's plot was found to be 5 to 17.5 ppm. The molar absorptivity and Sandell's sensitivity of Cu (II)-NBIMMT in chloroform was 2.825 x 10³ L mol-1 cm-1 and 0.0224μgcm-2, respectively. The optimum extraction conditions were evaluated by studying various parameters such as effect of pH, reagent concentration, solvents, shaking time and foreign ions. The use of masking agents enhances the selectivity of method. The composition of the extracted species was determined by Job's method, mole ratio method and verified by log-log plot. The ratio of Cu (II): NBIMMT was found to be 1:2. The proposed method was successfully applied for the determination of Cu (II) in synthetic mixtures, pharmaceutical samples and alloys.