Acid-base indicator properties of dyes from local flowers: Cassia aungostifolia Linn., Thevetia peruviana (Pers.) K. Schum and Thevetia thvetiodes (Kunth) K. Schum

Abstract

Indicators used in titration show well-marked changes of color in certain intervals of pH. Most of these indicators are organic dyes and are of synthetic origin. The environmental pollution caused by chemical industries in the synthesis of organic dyes had made the scientist in the developing country to enter in to an era, in which plant product serve as an alternative to synthetic products. The advantages of the plant products are local and easy accessibility, environmental friendly nature, and lower price compare to the synthetic products. Herbs are non-polluting renewable supplies of chipper products for the worlds growing population. Natural pigments in plants are highly colored substances and may show color changes with variation of pH. Curcumin isolated from Curcuma longa is as example of natural indicator used in analytical chemistry. Hence the work was carried out to study the indicator property of flowers Cassia aungostifolia Linn., Thevetia peruviana (Pers.) K. Schum and Thevetia thvetiodes (Kunth) K. Schum from ethanolic extract. It was found that the extract changes the color at different pH and can be used successfully as a compound indicator.