Differentiation of Disaccharide Isomers by Temperature-Dependent In-Source Decay (TDISD) and DART-Q-TOF MS/MS

Abstract

Abstract. Helium direct analysis in real time (He-DART) mass spectrometry (MS) of some compounds, polysaccharides, for example, usually tends to be challenging because of the occurrence of prominent in-source decay (ISD), which was considered as an undesired side reaction, as it complicated the resulting mass spectra. Our approach is to take advantage of an efficient and practical method termed the temperature-dependent ISD (TDISD) technique combined with fragmentation of the dehydrated dimers using DART Q-TOF tandem mass spectrometry for differentiation of disaccharide isomers. In this study, cross-ring cleavages and non-ovalent complexes were detected in the spectra of the saccharides. It was observed that the gas heater temperature had a significant effect on the absence or presence of signal in DART spectra. At high gas temperature, ions in high mass region began to appear. Based on the types of crossring cleavages and noncovalent complexes, disaccharide isomers with different linkage positions can be differentiated in both positive and negative ion modes at a lower DART gas temperature. Additionally, anomeric configurations were assigned on the basis of the relative abundance ratio of m/z 198:342 obtained by the comparison of the positive ion mode tandem mass spectrum of an α isomer dimer generated at higher DART gas temperature and that of the corresponding β one. In general, this method is easy, fast, effective, and robust for identifying disaccharide isomers.

Rapid detection of bacterial endotoxins in ophthalmic viscosurgical device materials by direct analysis in real time mass spectrometry

“…S2 in SI. DART can generate radical, cluster or/and protonated/deprotonated ions [33,45], however, ammonium adduct is common for carbohydrates via DART ionization according to literature studies [46–50]. For example, m/z 198 is identified as ammonium adduct of monosaccharide in positive mode, [M + NH 4 ] + ; ions of m/z 180 were confirmed to be ammonium adduct of water loss product from hexose [M + NH 4 -H 2 O] + ; m/z values of 163, 145, 127 are protonated ions resulted from series of water loss from hexose as annotated (Table 1).…”

Rapid fingerprint analysis for herbal polysaccharides using direct analysis in real‐time ionization mass spectrometry

“…Figure 2 With the investigation of various monosaccharide standards with DART-MS, it was found that the pyrolysis fragmentation pattern of polysaccharide is not the simple addition of the mass peaks from different monomers. 31,33,34 The direct thermal decomposition of large saccharides using DART source is different from the traditional controlled acid hydrolysis, and its detailed cleavage pathway is not clear yet. The small fragments generated from DART-MS can reveal the structural diversity of polysaccharides somewhat, but it is probably not adequate for the structure elucidation of polysaccharide macromolecules.…”

Easily fabricated ion source for characterizing mixtures of organic compounds by direct analysis in real time mass spectrometry

“…59,64,66 Applications adjusting the DART gas heater temperature have been used to characterize pyrolysis product evolution, 67-69 complex sample differentiation, [70][71][72] and to induce fragmentation of known molecules at higher temperatures (150-400 C). [73][74][75] Additionally, temperature programmed desorption (TPD) has been used in petroleomics studies with success at helping to simplify analysis. 65 Using the EZ-DART source we examined the TPD analysis of a PPG sample (described in the ESI †) and a viscous liquid asphalt, shown here, demonstrating that methods requiring DART heater adjustment can be used with the EZ-DART source.…”