Kau YC, Wong KM, Shyr MH, Lee YH, Tsai TH. Simultaneous determination of unbound ropivacaine in rat blood and brain using microdialysis. Journal of Chromatography B: Biomedical Sciences and Applications. 2001 Aug;760(1):107–12. doi: 10.1016/s0378-4347(01)00258-4.