Abstract. Many studies have investigated that natural plant extracts could be used as natural indicators, which are alternatives to commercial pH indicators used in acid-base lessons. However, no study has yet delved into developing and assessing purple sweet potato (Ipomoea batatas L.), locally called kamot,e as a potential material for creating localized pH paper (LpP). Therefore, this study was conducted to develop a pH paper for kamote leaf extract (KLEpP) and compare it with commercial pH paper and kamote leaf extract (KLE) to assess its potential as an LpP. The research is experimental and comparative. It focused on determining how KLEpP compares with commercial pH paper and kamote leaf extract (KLE). Additionally, the study analyzed the purple sweet potato extract for potential anthocyanin content using Fourier Transform Infrared (FTIR) Spectroscopy. Results indicated that the color of KLEpP shifts from light green to pink when immersed in a pH three standard. Further color changes were observed at pH 13 and 14, transitioning from light green to yellow-greenish and yellowish, respectively. While the color changes of KLEpP closely resemble those of KLE, the latter exhibited a wider spectrum of color changes. Notably, PSPLE demonstrated consistent color changes from pH 1 to 5, with a stronger pink at pH 3. The FTIR analysis revealed peaks indicative of various functional groups (hydroxyl groups, aldehyde group, aromatic group, hydrocarbon group, ester group bond, and C-O bond), signifying the presence of anthocyanins. The findings suggested that KLEpP has the potential to be an LpP and a practical alternative to commercial pH paper for teaching acid-base concepts. Furthermore, it could be employed to determine the pH of household materials.

Keywords: Acid-base indicator; Localized pH paper; Natural indicator; pH paper, Sweet potato.