Formation of the bisulfite anion (HSO₃^–, m/z 81) upon collision‐induced dissociation of anions derived from organic sulfonic acids

Abstract

In the negative-ion collision-induced dissociation mass spectra of most organic sulfonates, the base peak is observed at m/z 80 for the sulfur trioxide radical anion (SO(3) (-·) ). In contrast, the product-ion spectra of a few sulfonates, such as cysteic acid, aminomethanesulfonate, and 2-phenylethanesulfonate, show the base peak at m/z 81 for the bisulfite anion (HSO(3) (-) ). An investigation with an extensive variety of sulfonates revealed that the presence of a hydrogen atom at the β-position relative to the sulfur atom is a prerequisite for the formation of the bisulfite anion. The formation of HSO(3) (-) is highly favored when the atom at the β-position is nitrogen, or the leaving neutral species is a highly conjugated molecule such as styrene or acrylic acid. Deuterium-exchange experiments with aminomethanesulfonate demonstrated that the hydrogen for HSO(3) (-) formation is transferred from the β-position. The presence of a peak at m/z 80 in the spectrum of 2-sulfoacetic acid, in contrast to a peak at m/z 81 in that of 3-sulfopropanoic acid, corroborated the proposed hydrogen transfer mechanism. For diacidic compounds, such as 4-sulfobutanoic acid and cysteic acid, the m/z 81 ion can be formed by an alternative mechanism, in which the negative charge of the carboxylate moiety attacks the α-carbon relative to the sulfur atom. Experiments conducted with deuterium-exchanged and deuterium-labeled analogs of sulfocarboxylic acids demonstrated that the formation of the bisulfite anion resulted either from a hydrogen transfer from the β-carbon, or from a direct attack by the carboxylate moiety on the α-carbon.

High-throughput analysis of amino acids in plant materials by single quadrupole mass spectrometry

“…To the best of our knowledge, stable isotopes of the oxidized sulphur-containing amino acids methionine sulfone and cysteic acid, which are present in oxidized samples, have never before been used as internal standards. They can easily be synthesized [ 28 ] and we have in this study successfully used them as internal standards to significantly improve the quantification of these two amino acids.…”

“…Stable isotope labeled methionine sulfone and cysteic acid were not commercially available and were prepared in our lab from labeled methionine and cysteine according to the procedure by Jariwala et al [ 28 ]. In brief, a performic acid mixture was prepared by adding 9 mL of formic acid and 1 mL of hydrogen peroxide (30%).…”

Development of a Liquid Chromatography–Tandem Mass Spectrometry Method for the Determination of Sulfite in Food

“…However, previous studies have reported that these two structurally significant product ions are commonly observed during mass spectrometric analysis of sulfonic acids. 26 The MS/MS product ion ratios ranged from 1 to 8% for all of the standards and samples analyzed. For regulatory analyses, all ratios must be within 10% absolute of the value, with a signal-to-noise ratio of >3:1.…”

Photofragmentation and electron detachment of aromatic phosphonate, sulfonate and phosphate oxyanions

“…In accordance with previous collisionally-activated dissociation experiments, PF of the Ph-SO3  anion proceeds via SO3  loss. 6,29 The spectrum obtained by plotting the SO3  ion yield vs. the excitation energy is identical to the one recording the intensity of neutrals corresponding to the temporal profile edge, i.e. where the signal is a measure of neutrals originated in a dissociation process (having an excess of kinetic energy).…”