Mass Spectrometric Analysis of Water-insoluble Yellow Monoazo Pigments

Water-insoluble Yellow Monoazo Pigments were examined in order to establish a new analytical system using mass spectrometry. The characteristic ions observed were as follows: molecular ions, amine-component ions which are formed by the scission of the amide bond with hydrogen transfer and which are the most intense ones, ions at m⁄e: 43, and, in some cases, further-decomposed ions from the amine-component ions. A new analytical system was established on the basis of the analysis of the mass fragmentations of 27 samples, and applied to three unknown samples. The structure of these pigments can be deduced from the low-resolution mass spectra for those derived from substituted anilines, and from the high-resolution spectra for those derived from other amines.