Preparation of Acid – Base Indicator Papers Using Calyces of Habiscuss Sabdariffa (Zobo)

Abstract

This research focuses on developing and assessing the performance of greenish-blue and pink paper indicators made from Hibiscus sabdariffa (zobo) calyces. The calyces were collected, processed, and ground into powder, which was then used to produce anthocyanin-based extracts. These extracts were treated with acidic and alkaline solutions to create pink and greenish-blue indicators, respectively. Paper strips were immersed in these solutions to produce the colour-changing indicators. The effectiveness of the prepared indicators was tested against standard litmus papers (SLP) in both acidic and basic environments. The pink Hibiscus sabdariffa indicator demonstrated 98.24% efficiency compared to red SLP, while the greenish-blue indicator showed 97.36% efficiency compared to blue SLP. Statistical analysis revealed that the pink indicator did not significantly differ from red SLP at the 95% confidence level but showed agreement at higher confidence levels. The greenish-blue indicator was consistent with blue SLP across all levels of confidence. In conclusion, the study suggests that Hibiscus sabdariffa indicators provide high performance and could be a cost-effective alternative to imported litmus papers. With large-scale production, these indicators could reduce import dependency and even be exported, contributing to foreign exchange earnings.