Preliminary Pharmaceutical Characterization of Some Flowers as Natural Indicator: Acid-Base Titration

Indicators used in titrations show well-marked changes of color in certain intervals of pH. Most of these indicators are organic dyes and are of synthetic origins. The present study was designated to evaluate the extracted flower petals of some easily available plants. A comparative study of Delonix regia Raf. and Caesalpina pulcherrima Swartz Obs. flower extracts with synthetic indicator viz. phenolphthalein and methyl red were carried out to evaluate the accuracy of flower extracts as acid-base indicator. The results indicated that flower extracts of these plants can be used as acid-base indicator in titration of strong acid with strong base because similar results were obtained by phenolphthalein and methyl red. In case of weak acid and weak base titration, the results obtained by the flower extract coincide with the results obtained by mixed indicator. The rationale behind using these natural indicators in preference to synthetic indicators is its easy availability, inertness, ease of preparation and cost effectiveness.