Fig. 2

Extracted ion chromatograms of an analytical standard at 5 ng, showing retention time of AT7519 and APAP and the isotopically labelled internal standards, d8-AT7519 and d4-APAP following separation on a Waters Acquity Class UPLC system on a BEH C18 column (100 × 2.1 mm; 1.7 µm) and a mobile phase system of water and methanol (0.5 mL/min; 50 °C) followed by positive ionisation mode electrospray ionisation and multiple reaction mode analysis on a QTrap 5500 mass spectrometer