Corolla of Roselle (Hibiscus sabdariffa L.) as acid-base indicator
Open Access
- 31 March 2013
- journal article
- Published by European Journal of Chemistry in European Journal of Chemistry
- Vol. 4 (1), 20-24
- https://doi.org/10.5155/eurjchem.4.1.20-24.620
Abstract
Acid-base titration requires indicators to show color change at each pH interval. Synthetic indicators applied recently have some negatives, such as chemical pollution, availability and expensive production cost. Effort to obtain natural product-based-indicator from corolla of Roselle (Hibiscus sabdariffa L.) has been conducted. Firstly, anthocyanin contained in the Roselle’s corolla was identified. Then, the indicator was obtained by extracting the corolla consecutively with n-hexane, ethyl acetate and methanol-HCl 0.5%. Then the filtrate was evaporated at 65 oC. The obtained indicator was applied in weak base-strong acid and weak acid-strong base titrations. The comparison indicators used in this research were methyl orange and phenolphthalein. The results showed that the Roselle’s corolla indicator gave red color in acidic solution, while green in basic solution. Additionally, its performance is similar to that of methyl orange.Keywords
This publication has 8 references indexed in Scilit:
- Impact of texturing using instant pressure drop treatment prior to solvent extraction of anthocyanins from Malaysian Roselle (Hibiscus sabdariffa)Food Chemistry, 2009
- SYNTHESIS OF AZO COMPOUNDS DERIVATIVE FROM EUGENOL AND ITS APPLICATION AS A TITRATION INDICATORIndonesian Journal of Chemistry, 2009
- Herbal indicators as a substituent to synthetic indicatorsInternational Journal of Green Pharmacy, 2008
- Phytochemical MethodsPublished by Springer Science and Business Media LLC ,1984
- Chemistry of anthocyanin pigments. 9. UV-visible spectrophotometric determination of the acidity constants of apigeninidin and three related 3-deoxyflavylium saltsJournal of the American Chemical Society, 1982
- Chemistry of anthocyanin pigments. 2. Kinetic and thermodynamic study of proton transfer, hydration, and tautomeric reactions of malvidin 3-glucosideJournal of the American Chemical Society, 1977
- The Systematic Identification of FlavonoidsPublished by Springer Science and Business Media LLC ,1970
- Spectral methods of characterizing anthocyaninsBiochemical Journal, 1958