Spectrophotometric Determination of Trace Heavy Metals in Groundwater with Novel Chelating Reagents

Abstract:

For quantification of trace heavy metals in groundwater samples employing a new set of chelating agents obtained through Schiff bases and azo compounds    . Heavy metals such as lead (Pb²⁺), cadmium (Cd²⁺), nickel (Ni²⁺), chromium (Cr³⁺), and copper (Cu²⁺) were examined in this study, and complex formation properties of these heavy metals with synthesized ligands have been analyzed under optimized parameters such as pH, metal-ligand ratio, and absorbance wavelength (λmax). Physicochemical properties of 35 ground water samples collected at chosen sampling sites were determined. Parameters such as pH, electrical conductivity (EC), total dissolved solids (TDS) and total hardness of the sample were considered along with the heavy metals. All spectrophotometric studies were carried out with the help of a UV-VIS Spectrophotometer. It was observed that stable and highly colored metal–ligand complexes were obtained, with maximum molar absorptivity and distinct absorption maxima corresponding to each metal ion. The new method proved to be linear (R² > 0.997), with low detection limits and good recovery values (97.6 to 99.5%) with acceptable precision. It was observed that copper possessed the highest stability constant, whereas cadmium had the least stable complex. Use of the method on actual groundwater samples showed the presence of trace amounts of other heavy metals.      Correlation analysis demonstrated positive relationships between electrical conductivity (EC), total dissolved solids (TDS), and the concentrations of lead (Pb), cadmium (Cd), nickel (Ni), chromium (Cr), and copper (Cu), indicating that higher EC and TDS values were associated with increased heavy metal concentrations in the groundwater samples.