CHANGES IN ANTOCYANINE COLOR OF PEACOCK FLOWER (Caesalpinia pulcherrima) DUE TO THE EFFECT OF SOLUTION pH ILLUSTRATED IN ANIMATION AS A LEARNING MEDIA

• Main Author: Ardiansyah, Maman
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/34284
• Institution: Institut Teknologi Bandung

One of the plants that can be used as an natural indicator is peacock flower (Caesalpinia pulcherrima) that is supposed to contain flavanoid compounds such as antocyanine, as indicated by the red color of its flowers. The purpose of this research is to carry out an extraction of the antocyanine compounds of peacock flower (Caesalpinia pulcherrima) as a natural indicator in determining the pH of solutions and in developing a learning medium through the animation of changes in antocyanine color due to solution pH. Dyes may serve as a natural indicator. The research showed the changes in antocyanine color of Britton Robinson buffer solution that yielded red, purple, and greenish yellow at pH 2-4, 5-8, and 9-12, respectively. The isolation of antocyanine compound extracts was conducted by a maceration using a solvent of 95% ethanol: 1% HCl (99:1) to produce crude extract with the yields of 16.76% and purplish antocyanine isolate with the yields of 5.98%. To separate antocyanine compounds from other organic compounds, TLC analysis and preparative TLC using the best eluent of n-butanol : glacial acetic acid : water (BAA) at a ratio of 40:1:50 was carried out. The identification of antocyanine compounds was conducted by UV-Vis spectrophotometer, FTIR and followed by 1H-NMR and LCMS. The separation using preparative TLC produced 4 bands with Rf values of 0.20; 0.65; 0.75; and 0.80. Based on analysis of UV-Vis spectrophotometer, the purplish isolates with Rf value of 0.65 have a maximum wavelength at a visible ray of 530.79 nm, while FTIR spectrum showed chromospheres and ausochrome functional groups at wave numbers of 3458.45 cm-1 (-OH), 2996.75 cm-1 (-C-H), 1620.25cm-1 (-C=C- aromatic), and 1096.16 cm- 1 (-C-O). Meanwhile, the results of analysis by 1H-NMR spectrophotometer showed a complex spectrum, but proton signals were visible at the chemical shifts of 6.0 – 8.5 ppm, indicating that the protons were bound to aromatic ring compound. The LCMS measurement result of the isolate showed two chromatograms at retention times of 2.0 and 2.35 minutes. The emerging spectrum of the chromatogram at retention time of 2.35 minute contained peak at [M+H] = 273.2159. The data corresponds to the value of the molecular weight of pelargonidin (m/z = 272.0640). The research results showed that the extract of peacock flower (Caesalpinia pulcherrima) contains antocyanine pelargonidin compounds. Based on the results of the characterization of antocyanine compounds and its application as indicator, then an animation has been developed to illustrate the changes in the color of antocyanine compounds in buffer solution as a learning media. Responses and outcomes from 3 high school students and 4 teachers showed that the developed animation has adequately performed a comprehensive overview of the relationship between the structure of the indicator compound with the change of solution pH.