Study of Natural Indicator in Quantitative Analysis with Special Reference to Acidimetry and Alkalimetry

Abstract

Use of Synthetic indicators, due to chemical hazards causing environmental newlinepollution, availability and cost has become difficult, hence the search for natural newlinecompounds as an acid base indicator was started. A study therefore has been carried newlineout on Hibiscus rosasinensis, Dahlia pinnata, Cannaindica, Butea monosperma, newlineBauhinia variegata, Celosia argentea, Delonixregia, Terminalia catappa leaf, newlineAcalyphawilkesiana leaf, Basellarubra fruit, Celosia argentea stem, BixaOrellana newlineseedsfor its use as natural acid-base indicator because of ease in availability, newlineinertness and ease of preparation and cost effectiveness. Natural indicators are easy to newlineprepare and are easily available. Volumetric titrations between acid and base show newlinesharp colour change at the equivalence point. The equivalence point obtained by newlinenatural sap indicator coincide with the equivalence point obtained by standard newlinesynthetic indicators as Methyl orange, Phenolphthalein, Phenol red etc. Aqueous newlineextract and methanolic extract of petals of flower like Butea monosperma, Hibiscus newlinerosasinensis, Dahlia pinnata, Cannaindica, Butea monosperma, Bauhinia variegata, newlineCelosia argentea, Delonixregia, Aqueous extract and methanolic extract ofleaf of newlineTerminalia catappa , Acalyphawilkesiana, Aqueous extract and methanolic extract of newlinefruit of Basellarubra, Aqueous extract and methanolic extract of Stem ofCelosia newlineargentea and Aqueous extract and methanolic extract of Seed of BixaOrellana etc. newlinecan be used for this purpose which contain anthocyanins as active component newlineresponsible for colour change. Thus natural sap indicators are found to be simple and newlineeconomical in acid base titrations. Such natural indicators also satisfy the principles newlinelaid down by Green Chemistry. This pigment was investigated using newlinespectrophotometric method. Pigments were extracted using cold water and a definite newlinevolume was added which gave accurate and reliable results for all the four different newlinetypes of neutralization titrations strong acid against strong base, strong acid against newlineweak base, weak