Pomegranate peel extract as an eco-friendly acid–base indicator and pH indicator paper.

Eco-friendly acid base indicators (anthocyanins) are always a center of attention in quantitative volumetric analysis as substitute for synthetic dye indicators. The purpose of the study is to promote utilization of Punica granatum (pomegranate) peel biomass by developing a novel eco-friendly acid–base indicator for titrimetric analysis. Pomegranate peel extract (PPEx) was prepared by ultrasonic probe sonication, a green method for extraction. The obtained extracts were evaluated for total phenol, anthocyanin content and the color change ability analysis (CIEL*a*b* analysis). The pKa of PPEx was determined, the effectiveness of PPEx as indicator was established in different acid–base titrations and compared with conventional synthetic indicators phenolphthalein and methyl orange. The aspirin powder and tablet (Ecosprin) were analyzed by using PPEx as indicator. An attempt was also made to develop PPEx pH indicator paper. The aqueous and ethanolic PPEx prepared by ultrasonic probe sonication contains 657.1 ± 21 and 718.1 ± 21 mg/LGAE of total phenols and 38.49 ± 0.83 and 42.91 ± 2.10 mgC3G/100gm of anthocyanins, respectively.The PPEx and pH indicator paper shows color change with the pH of solution. The pKa of PPEx was 7.14. PPEx was served as eco-friendly substitute for phenolphthalein and methyl orange indicators. PPEx was effective to analyze aspirin. The statistical analysis ensures the reliability and effectiveness of PPEx as an eco-friendly indicator in acid base titrations as substitute for the synthetic dye indicator. [ABSTRACT FROM AUTHOR]