Evaluating potential of dye extracted from Vitex doniana bark as reagent for quantitative UV-vis spectroscopic analysis of Ag+, Cu2+ And Zn2+ Ions

• Ag + , Cu 2+ And Zn 2+ determined by UV-Vis spectrophotometry using Vitex doniana dye. • The metal-dye complexation reaches equilibrium within 10 s. • FT-IR confirms O-H, C-O, and C=O groups mediate metal ion coordination. • UV-Vis spectra show significant bathochromic shifts, confirming complex formation. • Optimal pH, concentration, and time conditions enhance metal complexation. Heavy metal contamination poses significant environmental and health risks, necessitating cost-effective and sustainable detection methods. This study explores the use of a natural dye from Vitex doniana for metal ion detection. The dye was extracted using water, methanol, and ethanol, yielding 7.50 %, 4.80 %, and 1.69 %, respectively, and fractionated via flash chromatography. FT-IR analysis identified OH, C=O, and C-O functional groups, while UV-VIS spectrophotometry determined a maximum absorption wavelength of 271.0 nm. Complexation with Ag⁺, Cu²⁺, and Zn²⁺ induced bathochromic shifts to 281.4 nm, 350.0 nm, and 380.0 nm, respectively. Optimal pH conditions were 9 for Cu²⁺ and 4 for both Zn²⁺ and Ag⁺, with reaction times of 10 s for Ag⁺ and Cu²⁺ and 20 s for Zn²⁺. Calibration curves demonstrated linearity (1.00–9.00 ppm), underscoring the dye’s potential as a low-cost, eco-friendly reagent for heavy metal ion detection in environmental and industrial applications