Fig. 5: Data processing steps using MALDIquant (Bruker Biotyper Sirius data). | npj Vaccines

Fig. 5: Data processing steps using MALDIquant (Bruker Biotyper Sirius data).

From: Using matrix assisted laser desorption ionisation mass spectrometry combined with machine learning for vaccine authenticity screening

Fig. 5

a MALDIquant workflow. b Baseline drift correction using TopHat algorithm, spectra for hyaluronic acid. c Comparing the effect of pre and post probabilistic quotient normalisation (PQN) on the percentage relative standard deviation (RSD) for the vaccine, falsified constituent, and quality control (QC) sample replicates. d QC spectrum showing peaks labelled A–E used to illustrate m/z variation. e Box plots illustrating variation in m/z across 24 QC samples for peaks labelled A–E in part D. The line in the grey box indicates the median value, with the box limits showing the interquartile range. Whiskers extend to max and min values. f Comparing different signal-to-noise ratio (SNR) thresholds using an averaged mass spectrum incorporating authentic and falsified vaccines/constituents. Coloured coded numbering representing SNR thresholds.

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