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Mr Jason Raymond

Postgraduate Research Student

Academic and research departments

Department of Chemistry.


My research project


Natalicia J. Antunes, Nina Ince, Jason Raymond, Karin Kipper, Lewis Couchman, David W. Holt, Gilberto De Nucci, Atholl Johnston (2020) Quantification of mycophenolic acid in human plasma by liquid chromatography with time‐of‐flight mass spectrometry for therapeutic drug monitoring
This study presents, for the first time, the development and validation of a liquid chromatography and time‐of‐flight mass‐spectrometry (LC–TOF–MS) based assay to quantify mycophenolic acid (MPA) in patient samples as part of a routine therapeutic drug monitoring service. MPA was extracted from 50 μl human plasma by protein precipitation, using sulindac as internal standard (IS). Separation was obtained on a Luna™ Omega polar C18 column kept at 40°C. The mobile phase consisted of a mixture of acetonitrile–deionized water (50:50, v/v) with 0.1% formic acid at a flow rate of 350 μl/min. Analyte and IS were monitored on a TOF–MS using a Jet‐Stream™ (electrospray) interface running in positive mode. Assay performance was evaluated by analysing patient plasma ( = 69) and external quality assessment ( = 6) samples. The retention times were 2.66 and 2.18 min for MPA and IS, respectively. The lower limit of quantification of MPA was 0.1 μg/ml. The within‐ and between‐assay reproducibility results ranged from 1.81 to 10.72%. Patient and external quality assessment sample results were comparable with those obtained previously by an in‐house validated LC–MS/MS method. This method showed satisfactory analytical performance for the determination of MPA in plasma over the calibration range of 0.1–15.0 μg/ml.