For the monitoring phase of this study, four batches of commercial GLP-Fc fusion DP and one batch of DS were analysed by full MS only acquisition using a HRAM mass detector, after triplicate digestion as described previously. A chromatographic overlay of the drug substance and four commercial drug product batches is presented in Figure . The chromatograms for the four DP batches compare favourably to both each other and the DS. Peak retention time and symmetry were reproducible between injections (data not shown).