Fig. 9: MSn spectral tree of protonated arginine with annotations. | Communications Chemistry

Fig. 9: MSn spectral tree of protonated arginine with annotations.

From: A spectroscopic test suggests that fragment ion structure annotations in MS/MS libraries are frequently incorrect

Fig. 9

Annotations proposed by the MS libraries, Zhang et al.44, and ion spectroscopy (this work) are compared. Structures in brackets are tentative assignments. * For METLIN structures, a proton must be placed at one of the carbon atoms to arrive at an ion of the correct m/z value. ** Annotations based on the spectroscopic analysis shown in Supplementary Figs. S25–S33. *** A more detailed analysis of the m/z 112 fragment ion is presented in Supplementary Fig. S35 and Supplementary Note 2.

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