A Fundamental Tandem Mass Spectrometry Study of the Collision‐Activated Dissociation of Small Deprotonated Molecules Related to Lignin

Abstract

The collision-activated fragmentation pathways and reaction mechanisms of 34 deprotonated model compounds representative of lignin degradation products were explored experimentally and computationally. The compounds were evaporated and ionized by using negative-ion mode electrospray ionization doped with NaOH to produce abundant deprotonated molecules. The ions were isolated and subjected to collision-activated dissociation (CAD). Their fragment ions were then isolated and also subjected to CAD. This was repeated until no further fragmentation was observed (up to MS ). This approach enabled the identification of characteristic reaction pathways and delineation of reasonable fragmentation mechanisms for deprotonated molecules containing various functional groups. The varying fragmentation patterns observed for different types of compounds allow for the identification of the functionalities in these compounds. This information was utilized to identify the presence of specific functionalities and their combinations in molecules in an organosolv lignin sample.

Chemical composition analysis, antioxidant activity, and target cell‐based screening of the potential active components in jujube and its fermented product

“…163.0395, error 3.492 ppm) and fragment ion at m/z 119.0491 (C 8 H 7 O) generated by [M‐H‐CO 2 ] – was identified to be coumaric acid, which was identical with the fragmentation regularity of p‐coumaric acid reported by Marcum et al. (2016). Compound 57 was tentatively classified as 7‐(E)‐9‐ketohexadecarbone‐7‐enoic acid or its isomer.…”

Loss of CO2 from Monodeprotonated Phthalic Acid upon Photodissociation and Dissociative Electron Detachment

“…7 In addition, collision activated dissociation studies performed on several substituted aryl carboxylic anions have also revealed loss of CO 2 molecules. 8,9 However, the UV electronic excitation of deprotonated benzoic acid proved to be totally inefficient to induce fragmentation of the anion, and the molecular anion remained intact. 10 Remarkably, the opposite happens for the deprotonated naphthoic acid homologue, which exhibits decarboxylative fragmentation due to the opening of a new low-energy channel involving internal conversion and dissociation in the ground state.…”

Mass spectrometry‐based methods for the advanced characterization and structural analysis of lignin: A review

“…They were able to identify and count various oxygen-containing functionalities for their individual analytes (carboxylic acid, hydroxymethyl, acetyl, keto, aldehyde, methoxy, aliphatic hydroxy, and nitro groups) and then applied their method to LC-MS/MS analysis for a mixture of four of the compounds. This proved the applicability of using higher-order MS n analyses to better understand the composition of small lignin-related compounds using even a simple low-resolution, ion trap MS. A follow up study by Marcum et al (2016) continued this study, looking at CID spectra of 34 model lignin degradation products via both experimental and computational approaches. MS/MS experiments up to MS 6 were performed to characterize these fragments and the fragmentation patterns allowed the researchers to clearly distinguish carboxylic acid, aldehyde, ester, and phenol groups.…”

“…Later, Zhu et al expanded on these fundamental approaches by including ion-molecule reactions with diethylmethoxyborane (DEMB) to identify phenol functionalities in deprotonated monomeric and dimeric lignin degradation products via tandem MS. The group began by analyzing model lignin-like compounds containing phenol, carboxylic acid, and other functionalities via negative ESI ionization with an ion trap MS, including NaOH as a dopant (Zhu et al, 2016). All analytes were deprotonated to form [M-H]ions and then allowed to react with DEMB in an external reagent mixing manifold, forming DEMB adduct ions ([M-H + DEMB] -), some also having lost a methanol molecule ([M-H + DEMB-MeOH] -).…”