Optimization and Validation of Caffeine in Robusta Coffee (Coffea canephora), Black Tea (Camellia sinensis), and Cocoa (Theobroma cacao L.) Using RP-HPLC Liquid-liquid Extraction. J Pharm Sci Community [Internet]. 2026 Jun. 12 [cited 2026 Jun. 13];23(1):114-23. Available from: https://ejournal.usd.ac.id/index.php/jfsk/article/view/1086