ECO-FRIENDLY NATURAL ACID-BASE INDICATOR PROPERTIES OF FOUR FLOWERING PLANTS FROM WESTERN GHATS

Objective: The present study aims to evaluate the indicator property of ethanolic extract of the flowers of the Quisqualis indica L, Pentas lanceolata, Melastoma malabathricum L and Impatiens acaulis Methods: Four different types of Acid-base titrations such as strong acid against the strong base, strong acid against a weak base, weak acid against the strong base and weak acid against weak base were carried out in the present study. Two acids (HCl and CH3COOH) and two bases (NaOH and NH4OH) were selected for acid-base titration. 0.1N strength of these acids and bases were used.Results: The titration values were very close with an equivalence point obtained by standard indicator phenolphthaleinConclusion: The work proved to be acceptable in introducing natural pigments as a substitute to the synthetic acid-base indicators by adopting the principles of green chemistry.Keywords: Quisqualis indica L., Pentas lanceolata, Melastoma malabathricum L., Impatiens acaulis, Flavonoids, Natural pigments, Acid-Base titratio