Study of Melastoma malabathricum Fruit Dye as Green Alternative to Synthetic Indicators in Acid-Base Titration

The growing concern over the environmental and health impacts of synthetic acid-base indicators has intensified the search for sustainable and eco-friendly alternatives. In this study, the feasibility of using Melastoma malabathricum fruit extract as a natural acid-base indicator was systematically evaluated. Aqueous and ethanolic extracts of the fruit dye were prepared and employed in various acid-base titrations. The pH dependent colour transition of the extracts, exhibiting red hues in acidic media and blackish blue in alkaline conditions enables clear end point detection. Titremetric analyses involving weak acid-strong base (CH3COOH-NaOH) and strong acid-weak base (HCl-NH4OH) systems produced end points comparable with those obtained using standard synthetic indicators such as phenolphthalein and methyl orange. However, the extracts showed limited applicability in strong acid-strong base (HCl-NaOH) titrations. The results demonstrates that Melastoma malabathricum fruit extract serves as an effective, non-toxic and biodegradable indicator for selected acid-base titrations, offering a viable green alternative to conventional synthetic indicators. This study highlights the potential of locally available plant resources in promoting sustainable practices in analytical chemistry.