Development and validation of an analytical method by HPLC-DAD for determination of caffeine in products based on guarana extracts (Paullinia cupana). Brazilian Journal of Pharmaceutical Sciences, [S. l.], v. 59, p. https://doi.org/10.1590/s2175–97902023e22106, 2023. DOI: 10.1590/s2175-97902023e22106. Disponível em: https://revistas.usp.br/bjps/article/view/212197.. Acesso em: 8 may. 2024.