First and second derivative spectrophotometric determination of copper(II) using 2-acetylthiophene-4-phenyl-3-thiosemicarbazone

The reagent, 2-acetylthiophene-4-phenyl-3-thiosemicarbazone (ATPT) has been used for the spectrophotometric determination of copper(II) in aqueous medium. The reagent gives intense colour reaction with copper(II) in sodium acetate-acetic acid buffer medium. Maximum colour intensity observed in the pH range 3.0-6.0. First and second derivative methods have been developed for the determination of copper(II) in aqueous medium. First derivative spectrum of Cu-ATPT complex has maximum amplitude at 420 nm which is selected in analytical studies. On the other hand the second derivative spectrum of Cu-ATPT complex exhibits maximum amplitude at 410 urn (peak) and 455 nm (valley) and the zero cross at 485 nm. The amplitude at 410 nm is proportional to the amount of copper(II). Therefore, this wavelength is chosen in second derivative method.