Investigation of Murexide-Zn(II) Complexes in Water-Isopropanol Mixtures: Spectroscopic Analysis and Stability Studies

Abstract

This study investigates the complexes formed between murexide and Zn (II) ion in water-isopropanol mixtures using spectroscopic analysis. The impact of varying solvent ratios on the absorption spectrum of murexide and its complexes with Zn (II) ion is examined. Furthermore, the influence of pH, time, and interfering ions on the stability of the complexes is investigated for three different isopropanol-water ratios with varying polarities (8:2, 6:4, and 3:7). The molar ratio and stability constants of these complexes are determined using the continuous variations method. The results indicate that complexes with a molar ratio of 1:2 (ML2) are formed at the ratios 8:2 and 6:4, while a molar ratio of 1:1 (ML) is observed at the ratio 3:7. The formation constants (Kf) for the complexes are found to be 7.32x1010, 1.10x1011, and 3.98x105 for the three ratios, respectively, suggesting an inverse relationship between complex stability and water content in the solvent mixture. Additionally, the spectroscopic method employed is evaluated based on sensitivity (0.0406 ppm⁻¹), detection limit (0.016 ppm), and quantification limit (0.054 ppm). The linear range of concentration, as determined by Beer‒Lambert’s law, spans from 0.2 ppm to 3.93 ppm.