Quantification of Total Phenol Concentration in Ethanol Extracts of Red and Black Betel Leaves Using UV-Vis Spectrophotometric Method: Penentuan Kandungan Total Fenol Dalam Ekstrak Etanol Daun Sirih Merah dan Hitam Dengan Memanfaatkan Teknik Spektrofotometri. Pharmasci [Internet]. 2024 Jun. 11 [cited 2025 Oct. 26];9(1):29-33. Available from: https://ejournal.akfarsurabaya.ac.id/index.php/jps/article/view/388