THE pH ROUTE OF ROSELLA FLOWER (HIBISCUS SABDARIFFA L) AS AN ACID-BASE INDICATOR

Abstract

Rosella flower contains anthocyanin which has a very unique color change, it is red in acidic conditions and becomes blue in basic conditions, but is not colored in neutral conditions. Researches have been conducted on the use of rosella flower extract as an acid-base indicator, showing that the extract was red in acidic conditions and green in basic conditions. This follow-up study determined the pH route of rosella flower extract. The pH route was determined through several stages, namely maceration extraction, anthocyanin isolation as an acid-base indicator, and structural analysis using UV-Vis, FTIR and ¹HNMR spectrophotometers. Then the pH route was determined using the Lyalikov method, employing phenolphthalein and methyl orange as the comparative indicators. The results indicated that rosella flower extract has a pH route almost the same as its comparative indicators, so that rosella flower extract can be an alternative for phenolphthalein and methyl orange which are synthetic indicators.