Fig. 2. Representative mass spectra (m/z 0–900) for α-cyano-4-hydroxycinnamic acid (CHCA) matrix, Engerix B vaccine and eight samples of other compounds and mixtures previously reported as being constituents of falsified vaccines.

a Biotyper Sirius mass spectra. b VITEK mass spectrometry (MS) spectra. Through the presence, absence and relative intensity ratios of peaks in the spectra, the genuine vaccine can be distinguished from the falsified constituents by manual inspection of spectra. Common matrix peaks are indicated by shaded bars.