Mass Spectrometric Distinction of Free Phenoxy Fatty Acids from Phenols Part I: Application of El-Mass Spectrometry

Abstract

By comparison of electron impact mass spectra of 16 phenoxy fatty acids with their corresponding phenols, it becomes obvious that the major parts of both spectra are identical.

The dominating signal is the phenol ion. It corresponds to the molecule ion for free phenols and to that fragment for the phenoxy fatty acids which is formed by the loss of the acid moiety under proton migration. As the signals of higher masses than the phenol ions are small in most cases, and as these substances have comparable chromatographic properties, correct identification in mixtures is difficult to achieve. The spectra of both classes of compounds are given to allow the selection of specific signals for the differentiation of fatty acids versus phenols, when this is possible.