Evaluating torenia fournieri Flower Extract as a Natural Acid-Base Titration Indicator

This research aims to evaluate the potential of torenia fournieri flower extract as an alternative acid-base indicator that is safe, cheap and environmentally friendly compared to synthetic indicators.Synthetic indicators commonly used today have several disadvantages, such as being dangerous for the environment and health, expensive, and not easily decomposed.torenia fournieri flower extract was obtained through a maceration process and tested in various solutions, including HCl, NaOH, CH3COOH, NH4OH, as well as in phosphate buffer with a pH range of 1-12.The results showed that torenia fournieri flower (TFF) extract was red in a strong acid solution, pink in a weak acid solution, green in a strong base solution, and yellow in a weak base solution.In tests with buffer solutions, there are four different color ranges: red at pH 1-6, colorless at pH 7, yellow at pH 8, and dark green at pH 9-12.In addition, in the titration of strong acids and strong bases, the color changes from pink to colorless in the pH range 5.41-7.03,while the reference indicator, phenolphthalein, changes from colorless to purple in the pH range 5.87-7.07.In the titration of a weak base and a strong acid, the color change occurs in the pH range 5.4-6.2, from pinkgreenish yellow, while in the comparison indicator, methyl orange, the color change occurs in the pH range 3.2-4.3,from red-orange.In titrations of weak acids and strong bases, color changes occur in the pH range 5.41-8.22,from pink-yellow to greenish, while in the comparison indicator phenolphthalein, color changes occur in the pH range 5.39-8.20,from colorless to purple.It can be concluded that torenia fournieri flower (TFF) extract shows a color change ability similar to phenolphthalein (PP) and methyl orange indicators, but with a narrower color range.Therefore, torenia fournieri flower extract can be used as a safe, cheap and environmentally friendly alternative acid-base indicator, both for strong acid-strong base titrations and weak acid-strong base titrations.However, further research needs to be carried out to evaluate the reproducibility and stability of torenia fournieri flower extract as an indicator.