Acid-Base Indicator Paper Extracted from Rose (Rosa damascena Mill) and Hibiscus Flower (Hibiscus rosa-sinensis) Ethanols

This research aims to develop paper indicators extracted from rose (Rosa damascena Mill) and Hibiscus flower (Hibiscus rosa) ethanols. These flowers have anthocyanin pigment and are sensitive toward acidity (pH). The contents make rose and Hibiscus flower to have potentials as natural indicators. The anthocyanin pigment extraction from both flowers was done by maceration method with 96% ethanol solvent. It was done with 24 -hour soaking period. The ethanol extracts from rose and Hibiscus were calibrated by buffer solution with pH 1-12. Then, it was continued by cutting Whatman 42-paper sized ±5x1 cm. The paper was soaked in rose ethanol extract (Rosa damascena Mill) and Hibiscus flower (Hibiscus rosa) with a ratio of 1:1 for 24 hours. The indicator papers were dried then tested in acid-base solution. The indicator papers showed a colour change from pink, found in acid solution, to green-brownish, found in base solution. The findings showed that the rose and Hibiscus flower indicator papers could be used as an acid- base indicator. The produced indicator papers have several superiorities. They are made from natural materials, less- polluted, more economical, more durable, and have contrast colour gradation.