Utilization of Waste Red Onion (Allium cepa L.) Peels as Natural Acid-Base Indicator

This study addresses the growing demand for sustainable analytical practices by evaluating the potential of ethanolic extract of waste red onion (Allium cepa L.) peels as a bio-indicator for acid-base titration in volumetric analysis. The extract was prepared through maceration in ethanol and characterized using phytochemical screening, UV-Vis, and FTIR spectroscopy. Its performance was assessed in strong acid-strong base titration and compared with conventional synthetic indicators, methyl orange, phenolphthalein, methyl red and bromothymol blue. Statistical analysis using one-way ANOVA revealed significant difference (p < 0.05) between the titre values obtained with the red onion peel extract and the synthetic indicators. However, Tukey Pairwise comparisons confirmed no significant difference between methyl orange, methyl red, bromothymol blue and red onion peels extract except phenolphthalein. These findings suggest that the red onion peel extract is a promising, eco-friendly, and effective alternative to synthetic indicators in strong acid-base titration, with potential applications in sustainable analytical practices