Temperature dependence of dissociative electron attachment to molecules of gentisic acid, hydroquinone and p-benzoquinone

Abstract

The temperature dependence of dissociative electron attachment to molecules of gentisic acid (2,5-dihydroxybenzoic acid) as well as to the products of its decomposition, namely molecules of hydroquinone and p-benzoquinone, has been investigated by means of electron capture negative ion mass spectrometry (ECNI-MS). We have obtained the negative ion yield as a function of incident electron energy for decay channels corresponding to m/ z 108 which are [M−CO 2−H 2] − anion in the spectrum of gentisic acid, [M−H 2] − anion in the spectrum of hydroquinone and [M] − parent long-lived anion in the spectrum of p-benzoquinone. It was shown that molecules of carbon dioxide may be formed at high temperature not only by decarboxylation of gentisic acid but also by capture of low-energy electrons (about 1 eV). Such a fact has a great importance for understanding of the problem of analyte desorption in matrix assisted laser desorption/ionization (MALDI) mass spectrometry in according to CO 2-MALDI model where the desorption of large biomolecules is explained in terms of gas-bubbles formation by thermal decomposition of molecules of MALDI matrix.