Fig 1. Development of LC-MS/MS methods to quantitate lopinavir, lopinavir M1, nelfinavir, nelfinavir M8, ritonavir, and hydroxy ritonavir in human liver microsomes.

MS/MS spectra of (A) lopinavir, (B) lopinavir M1, (C) nelfinavir, (D) nelfinavir M8, (E) ritonavir, (F) hydroxy ritonavir with ESI proton adducts [M+H]⁺ in positive mode. The y-axis shows intensity (CPS, count per second) and the x-axis shows the mass to charge ratio (m/z, amu).