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oai:ojs.www.eurjchem.com:article/620 2013-03-30T23:10:27Z eurjchem:ART driver

Corolla of Roselle (Hibiscus sabdariffa L.) as acid-base indicator Nuryanti, Siti Matsjeh, Sabirin Anwar, Chairil Raharjo, Tri Joko Hamzah, Baharuddin Indicator Methyl orange Phenolphthalein Corolla of Roselle Acid-base titration Hibiscus sabdariffa L. 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. Atlanta Publishing House LLC 2013-03-31 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion application/pdf https://www.eurjchem.com/index.php/eurjchem/article/view/620 10.5155/eurjchem.4.1.20-24.620 European Journal of Chemistry; Vol. 4 No. 1 (2013): March 2013; 20-24 2153-2257 2153-2249 eng https://www.eurjchem.com/index.php/eurjchem/article/view/620/PDF