Callistemon lanceolatus (Bottle Brush) Flower Extract as a Greener Alternative to Synthetic pH Indicators

In recent past, evolution in green chemistry has developed the need of application of plant pigments as pH indicators which prove to be a better alternative for demand of present day chemistry. The acid-base indicator properties of Callistemon flowers were evaluated. Colour pigments from flowers are extracted from the flowers using a cold solvent extraction. Stability of colour in the indicator was studied. Wavelengths of absorption was determined using ultraviolet spectrophotometer and the maximum wavelengths of absorption obtained for the extract fell within the visible region at 450nm.Equivalence point indicated sharp color changes. During volumetric experiments the equivalence points observed by the flower extract coincided with those obtained by standard indicators. Results show that natural indicators are found to be a very user friendly, non-toxic, cost-effective, uncomplicated, precise, comprehensible and eco-friendly and could be an excellent substitute for synthetic indicators.