Acid Base Indicator from Shoot-Leaves Ethanol Extract of Pucuk Merah (Syzygium oleana)

Abstract

Experiment on natural acid-base indicators is usually done by extracting the natural sources with certain solvent, testing the extract with acid, base and neutral solutions, observing the color changes, making conclusion and discharging the remaining extract at the end of the experiment. Production of long-lasting natural acid-base indicator is needed to reduce the discharged of chemicals excessively. This research was carried out to produce natural acid-base indicator from extract of shoot leaves of Syzygium oleana (SLS). The extraction was done by maceration technique using ethanol 95% for 13 h. The extract of SLS (SLS indicator solution) is then used to produce SLS indicator paper by soaking the filter paper in SLS indicator solution and followed by drying under shade. Both of the solution and paper indicators were tested for their color changes in pH solutions range of 1-13. Durability and performance of the indicator was investigated for 6 d. Absorbance of the indicator solution was measured under wavelength of 200-700 nm by using UV-Vis spectrophotometer. The results showed that, both of the indicators can be used as acid-base indicator; even it can be used to determine the pH range of solution. The color changes of SLS indicator in solution pH of 1-13 were pink-fade green-moss green-brown. Both of the indicators showed a good performance in their color change for 6 d of storage. Thus, the ethanol extract of SLS can be used as raw material to produce acid-base indicator.