738932.fig.002
Figure 2: Mass spectrum of 2-{[2-amino-2-(4-hydroxy-phenyl)-acetylamino]-carboxy-methyl}-5-methyl-1-oxo-1,2,3,6-tetrahydro-1λ-4-[1,3]thiazine-4-carboxylic acid with its parent molecular ion peak at mass/charge at 398.4 amu.