Flower Extract Tapak Dara (Catharanthus roseus L) as Acid–Base Indicator

Abstract

The aim of this research is to extract the tapak dara flower and prove it as an acid-base indicator. The tapak dara flower was washed with distilled water until clean, then ethyl acetate solvent was added and macerated. Subsequently filtered, then the filtered residue was extracted again with absolute methanol solvent. The extraction results were filtered using a gauze filter, then filtered again with filter paper. The filtered filtrate is ready to be used as an acid-base indicator. Then evaluated with a comparison indicator phenolphthalein and methyl orange for acid-base titration, namely a strong base with a strong acid, a weak base with a strong acid and a strong base with a weak acid. From the results of the study, it is known that the indicator of the extract of the tapak dara flower to show the equivalence point in the titration gives results that are equivalent to the comparison indicators. The results showed that indicators from tapak dara flower extract could be used instead of the synthetic indicators (phenolphthalein and methyl orange) that had been used so far.