Selective Separation and Preconcentration of Caffeine from Natural and Pharmaceutical Products using New Polyurethane Foams. Brazilian Journal of Pharmaceutical Sciences, [S. l.], v. 58, 2022. DOI: 10.1590/s2175-97902022e20175 . Disponível em: https://www.revistas.usp.br/bjps/article/view/205193.. Acesso em: 20 may. 2024.