Natural indicator for acid base titration from ethnobotanical resources of Tripura, India using green chemistry principles

There are several plants, insects which give us certain organic compounds that possess extended conjugated systems of alternating single and multiple bonds, which allow for the absorption of visible light, hence give us coloured compounds that can be used as pigments, bio-colours, or natural indicators. Natural Indicators can be cost-effective, environment friendly, and have excellent performance with sharp colour change in end points of the acid base titrations, which can work as an alternative of synthetic indicator. In a titration at the end point conjugated systems changes and accordingly the absorption of visible light changes, hence the colour changes. For sustainable development, a list of suggestion based on Green Chemistry principles should be referred and one of them is natural Indicators. In the present research the plant-part extract of medicinally active plant species Vitis labrusca, Artocarpus heterophyllus, Basella alba, Punica granatum, Beta vulgaris, Curcuma longa, Terminalia chebula and Areca catechu have been experimentally found to be an alternative of phenopthalein and methyl orange for acid-base titration. These indicators are produced by the method of extraction using 100% distilled methanol. The extract was tested in solution with pH 1-12 and used as an indicator to identify the solutions and titration in acid-base topic. The study came to the conclusion that Vitis labrusca, Artocarpus heterophyllus, Basella alba, Punica granatum, Beta vulgaris, Curcuma longa, Terminalia chebula and Areca catechu could serve as an alternate source material for acid base indicators. The uses suggest an effort to have implemented the principles of green chemistry, including the prevention of the formation of hazardous wastes, the design of safe chemical products, the use of renewable materials, the design of materials that are easily degraded, and the use of safe solvents.