POTENTIAL OF DAYAK ONION SKIN (ELEUTHERINE PALMIFOLIA) EXTRACT AS AN ALTERNATIVE INDICATOR FOR ACID BASE TITRATION PRACTICUM

Abstract

Synthetic indicators such as phenolphthalein are used during acid-base titrations to determine the end point of the titration. These indicators are not environmentally friendly and the price is high. To overcome this, it is necessary to study the potential of natural indicators available in the environment, one of which was Dayak onion skin which has not been utilized after the tubers have been taken as an anti-cancer herbal medicine. The aim of this research was to determine the potential of Dayak onion skin (Eleutherine Palmifolia) as a natural indicator in acid-base titrations. The sampling collection of Dayak onions was done randomly in the city of Palangka Raya, Central Kalimantan. The method used in this study employed experimental techniques in the chemistry laboratory of FKIP ULM with the following steps: 1) Maceration of smoothed Dayak onion skin with 96% ethanol for 1, 2 and 3 days 2) Qualitative test of anthocyanin, color test with buffer pH 1-14, 3) Absorption measurement with a UV-Vis spectrophotometer at a wavelength of 200 - 400 nm, 4) Application of the extract as an indicator in acid-base titrations. The results showed that the optimum maceration time was on day 3 with an absorption of 4,520 at a wavelength of 380 nm. The application on the HCl – NaOH titration with a titration end point volume of 9.11 mL showed a color change from yellow to straw yellow, while the comparison indicator PP had a volume change of 8.57 mL with a color change from colorless to pink. The CH₃COOH – NaOH titration gave a result of 11.43 mL and the PP indicator was 11.01 mL. For the NaHCO₃ – HCl titration, the end point volume of the titration was 9.93 mL with a straw yellow – yellow color change and the MO indicator comparison was 10.27 mL with an orange – red color change. From the results of this research, there was a significant color change at the end point of the titration, so it can be stated that Dayak onion skin extract had the potential to be an alternative indicator in acid-base titration practice so that it can be a solution in reducing chemical pollution in the environment.