Analysis of bupivacaine enantiomers in plasma as total and unbound concentrations using LC-MS/MS:: application in a pharmacokinetic study of a parturient with placental transfer - Souza, Marília Cristina Oliveira; Marques, Maria Paula; Duarte, Geraldo; Lanchote, Vera Lúcia (Journal of Pharmaceutical and Biomedical Analysis, 2019)