Spectrophotometric determination of copper with N-salicylidene-thiosemicarbazone

N-Salicylidene-thiosemicarbazone is insoluble in cold water, but its copper complex is soluble and green. This reagent has been employed for the determination of Cu(II), as the chelate formation is selective and sensitive. The chelate compound gives the colored solution by adding powder of the reagent as much as 56 times of Cu(II) in mole to sample solution adjusted to pH 2.53.5 and allowing to stand the subsequent turbid solution at 60°C for 30 min1 hr. Excess of the reagent is filtered and the absorbance of the filtrate was measured at 630 mμ. From 1.0 to 7.0 mg of Cu(II) could be determined by the above procedure.