Quantification of femtomolar concentrations of the CYP3A substrate midazolam and its main metabolite 1'-hydroxymidazolam in human plasma using ultra performance liquid chromatography coupled to tandem mass spectrometry - Burhenne, Jürgen; Halama, Birte; Maurer, Monika; Riedel, Klaus-Dieter; Hohmann, Nicolas; Mikus, Gerd; Haefeli, Walter E. (Analytical & bioanalytical chemistry, 2012)