Optimization of Extraction Solvent for Analysis of Total Phenolic and Antioxidant Activity of Guava Leaves (Psidium guajava) using Simplex Centroid Design. J Jamu Indo [Internet]. 2023 Dec. 18 [cited 2024 Nov. 21];8(3):90-6. Available from: https://jamu-journal.ipb.ac.id/index.php/JJI/article/view/344