Spectrophotometric Investigations on Some Heavy Metals Cu, Ni, Co, and Mn to Evaluate Their Environmental Toxicity.

A simple, sensitive, and rapid spectrophotometric method for the determination of Cu(II), Ni(II), Co(II), and Mn(II) ions is proposed based on the complexation of metal ions with a synthesized ligand, 4-methylpiperazine dithiocarbamic acid, formed by the reaction of 4-methyl piperazine and carbon disulfide under cold conditions. The colored complex formed by the reaction of the synthesized ligand with these heavy metals in an aqueous acetonitrile medium exhibits absorbance maxima at 435, 395, 370, and 495 nm for Cu, Ni, Co, and Mn metals, respectively. Beer's law was valid within concentration ranges of 0.34–20.46, 0.49–39.81, 0.47–38.07, and 0.49–11.03 µg/mL for Cu, Ni, Co, and Mn, respectively. Various reaction parameters such as pH, volume of reagent, and solvents were carefully studied and optimized. The limits of detection and limits of quantification for Cu, Ni, Co, and Mn were found to be 1.4, 2.4, 1.1, and 1.1 µg/mL and 4.2, 7.2, 3.3, and 3.3 µg/mL, respectively. The method proved to be sensitive and rapid, requiring only a few minutes for sample analysis. The synthesized ligand and metal(II) 4-methyl piperazine dithiocarbamate complexes, M(4-methylPzdtc)2, were characterized by FTIR. The method was subsequently applied to vegetable and water samples spiked with the cations. The high recoveries of Cu, Ni, Co, and Mn from the proposed method indicate good accuracy and precision. [ABSTRACT FROM AUTHOR]