Direct Analysis in Real Time Mass Spectrometry for Characterization of Large Saccharides

Abstract

Polysaccharide characterization posts the most difficult challenge to available analytical technologies compared to other types of biomolecules. Plant polysaccharides are reported to have numerous medicinal values, but their effect can be different based on the types of plants, and even regions of productions and conditions of cultivation. However, the molecular basis of the differences of these polysaccharides is largely unknown. In this study, direct analysis in real time mass spectrometry (DART-MS) was used to generate polysaccharide fingerprints. Large saccharides can break down into characteristic small fragments in the DART source via pyrolysis, and the products are then detected by high resolution MS. Temperature was shown to be a crucial parameter for the decomposition of large polysaccharide. The general behavior of carbohydrates in DART-MS was also studied through the investigation of a number of mono- and oligosaccharide standards. The chemical formula and putative ionic forms of the fragments were proposed based on accurate mass with less than 10 ppm mass errors. Multivariate data analysis shows the clear differentiation of different plant species. Intensities of marker ions compared among samples also showed obvious differences. The combination of DART-MS analysis and mechanochemical extraction method used in this work demonstrates a simple, fast, and high throughput analytical protocol for the efficient evaluation of molecular features in plant polysaccharides.

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

“…DART ionization source is capable of breaking down large and intact polysaccharides into small fragments instantaneously. 31 In this work, the factors affecting the DART-MS analysis of polysaccharides were systematically studied. The intensities of the main fragments (peak areas of DART-MS extracted ion chromatogram) from different F I G U R E 1 Overall fingerprint protocol for herbal polysaccharides includes 40-60 s mechanochemical extraction (MCE), removal of impurities using ultrafiltration membrane with molecular weight cut-off (MWCO) of 3 kDa, and direct analysis in real-time mass spectrometry characterization.…”

“…29,30 We reported earlier the phenomenon that DART ion source is capable of breaking down intact polysaccharides instantaneously into small fragments. 31 This work presents a rapid, simple, and high throughput fingerprint protocol for herbal polysaccharides, which involves efficient mechanochemical extraction (MCE) followed by direct DART-MS characterization. The whole procedure can be accomplished in a few of minutes from raw materials.…”

Natural Product Discovery by Direct Analysis in Real Time Mass Spectrometry

“…However, DART MS obviates a separate hydrolysis step since polysaccharides undergo thermal decomposition during DART ionization, generating characteristic pro les consisting of smaller fragments (m/z <350) in the ion source. 20) Many of the signals correspond to mono-and oligosaccharides. is feature was e ectively used to characterize the origin of traditional Chinese herbal medicines (TCHM).…”

“…Ma et al showed that six di erent herbal TCHMs could be distinguished on the basis of plant polysaccharide decomposition products. 20) Individual species also could be identi ed when mixed with one or two other species, indicating distinct polysaccharide compositions for each herb. Moreover, the same TCHM from di erent production regions also could be separated on the basis of DART ionization-produced polysaccharide fragments.…”

Saccharose cluster ions as mass calibrants in positive-ion direct analysis in real time-mass spectrometry

“…However, in DART work dealing with saccharides or glycosides, the emphasis was not on achieving accurate mass or exploiting these cluster ions for mass calibration. [25][26][27] The combination of DART with the high resolving power and mass accuracy of Fourier transform ion cyclotron resonance (FT-ICR) [13][14][15]28,29 and Orbitrap analyzers [30][31][32] is particularly effective in compound identification. Highest mass accuracy is generally achieved by combining the procedure of instrument tuning and mass calibration in a dedicated method file.…”