Corolla of Roselle (Hibiscus sabdariffa L.) as acid-base indicator
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.
Keyword(s)
European Journal of Chemistry, 4 (1), (2013), 20-24
DOI: http://dx.doi.org/10.5155/eurjchem.4.1.20-24.620
References
[1]. Amor, B.; Allaf, K. J. Food Chem. 2009, 115, 820-825.
http://dx.doi.org/10.1016/j.foodchem.2008.12.094
[2]. Ologundudu, A.; Ologundudu, A. O.; Ololade, I. A.; Obi, F. O. Afr. J. Biochem. Res. 2009, 3(4), 140-144.
[3]. Harborne, J. B. Phytochemical Methods. A Guide to Modern Techniques of Plant Analysis, 2nd edition, Chapman & Hall, 1984.
http://dx.doi.org/10.1007/978-94-009-5570-7
PMCid:1193218
[4]. Torskangerpoll; Andersen, Q. M. J. Food Chem. 2004, 89, 427-444.
[5]. Bhagat, V. C.; Radheshyam, D. P.; Channerker, R. P.; Shetty, S. C.; Atul, A. S. J. Green Pharm. 2008, 2(3), 162-163.
http://dx.doi.org/10.4103/0973-8258.42735
[6]. Day, R. A.; Underwood, A. L. Quantitative Analysis, 6th edition, Prentice-Hall, 1998.
[7]. Harbone, J. B. J. Biochem. 1958, 70, 22-28.
[8]. Jackman, R. L.; Yada, R. Y.; Tung, M. A.; Speers, R. A. J. Food Biochem. 1987, 11, 179-208.
[9]. Andersen, Q. M.; Markham, K. R. Flavanoids: Chemistry, Biochemistry and Applications, Tailor & Francis, 2006.
[10]. Ukwueze, N. N.; Nwadinigwe, C. A.; Okoye, C. O. B.; Okoye, F. B. C. J. Phys. Sci. 2009, 4(2), 058-062.
[11]. Mabry, T. J.; Markham, K. R.; Thomas, M. B. The Systematic Identification of Flavonoids, Springer Verlag, 1970.
http://dx.doi.org/10.1007/978-3-642-88458-0
[12]. Purwono, B.; Mahardani, C. Indo. J. Chem. 2009, 9(1), 95-98.
[13]. Brouillard, R.; Delaporte, J. Am. Chem. Soc. 1977, 99, 8461-8468.
http://dx.doi.org/10.1021/ja00468a015
[14]. Brouillard, R.; Iacobucci, G. A.; Sweeny, J. G. J. Am. Chem. Soc. 1982, 104, 7585-7590.
http://dx.doi.org/10.1021/ja00390a033
Refbacks
- There are currently no refbacks.