Fig. 1

Overview of workflow comparing the five extraction methods in human plasma vs. serum. Five extraction methods, including three conventional (methanol, methanol/acetonitrile and acetonitrile) and two hybrid-SPE (with acetonitrile or methanol) methods, are performed in two different matrices (plasma vs. serum). All extracts are analysed according to (i) + ESI HILIC, (ii) − ESI HILIC, (iii) + ESI RP C18 and, (iv) − ESI RP C18. Finally, data analysis is evaluated across untargeted and targeted metabolomics approaches. MeOH methanol, MeOH:ACN methanol combined with acetonitrile, ACN acetonitrile, SPE solid preparation extraction, ESI electrospray ionisation, RP reverse phase, LC–MS: liquid chromatography coupled mass spectrometry