FT‐ICR‐MS Peak Intensity Normalization for Complex Mixture Analyses

Photochemical processing is a major transformation pathway for allochthonous and autochthonous dissolved organic matter (DOM). DOM consists of thousands or even millions of different molecules and the isomer-resolved identification molecular structures is still far from any analytical realization. The highest analytical resolution of DOM can be achieved on a molecular mass basis via Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). With this technique, the molecular elemental compositions of thousands of DOM components can be assessed, given that they are extractable from water (via e.g. solid phase extraction, SPE-DOM) and ionizable (e.g. via electrospray ionization).Increasing levels of DOC in drinking water reservoirs pose serious challenges for drinking water processing. Photochemical processes potentially influence the DOM quality in the reservoir water. The photo degradation and / or the photo production of DOM components in surface freshwater as function of cumulated radiation was rarely investigated. In order to fill this gap we performed an irradiation experiment with water from a shaded forest stream flowing into a large reservoir (Muldenberg, Germany). DOC concentration, UV absorption, excitation-emission-matrices (EEMs) including calculated PARAFAC components and fluorescence indices, and FT-ICR MS derived molecular formulas of SPE-DOM were recorded at 13 different time points. The cumulated radiation was recorded during six days of solar irradiation (sunny days in August at 50.401847 deg. latitude and 12.380528 deg. longitude). Changes in relative peak intensity of DOM components as function of cumulated radiation were evaluated both by Spearman`s rank correlation and linear regression.We found components with different types of photo reaction behavior. Relative aliphatic components like C9H12O5 were identified as photo products showing a monotonous mass peak intensity increase with irradiation time. Highly unsaturated and oxygen-rich components like C15H6O8 showed a more or less monotonous intensity decrease indicating photo degradation. Many similar components were positively correlated to the humic-like fluorescence intensity and the humification index (HIX). The strong degradation of these components can explain the high loss of fluorescence intensity and the drop of the HIX in our experiment. As a result of the high temporal resolution in our experiment (i.e. intensity change as function of cumulated irradiation) we found another type of photo reaction. Components like C15H16O8 showed first increasing and then decreasing intensity indicating the formation of intermediate products.In general, the river DOM from the forested catchment area showed high potential for photochemical transformations which probably occur in the sunlight exposed predam of the drinking water reservoir.

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Online counter gradient LC-FT-ICR-MS enables detection of highly polar natural organic matter fractions

10.5194/egusphere-egu21-4836 ◽

2021 ◽

Author(s):

Limei Han ◽

Jan M. Kaesler ◽

Chang Peng ◽

Thorsten Reemtsma ◽

Oliver J. Lichentfeld

Keyword(s):

Organic Matter ◽

Natural Organic Matter ◽

Method Development ◽

Complex Mixture ◽

Gradient Elution ◽

Elemental Ratios ◽

Organic Matter Fractions ◽

Development And Validation ◽

Ft Icr Ms ◽

Ft Icr

Natural organic matter (NOM) is a highly complex mixture of natural organic molecules. The hyphenation of liquid chromatography (LC) with ESI-FT-ICR MS for the molecular characterization of NOM have shown to be a promising approach. However, due to changing solvent composition during gradient elution in LC-FT-ICR-MS, ionization conditions also change throughout the chromatographic separation process. In this study, we applied a post-LC column counter gradient (CG) to ensure stable solvent conditions for transient ESI-MS signals. SRFA and a peat pore water samples were used as representative dissolved NOM samples for method development and validation. Our results show that in the isocratic range segment, the TIC intensities of CG was increased by a factor of 1.5 fold, as compared to the standard gradient (SG) method. In addition, the application of the CASI mode for low abundance fractions revealed over 3 times more molecular formulas (especially for CHNO, CHOS, CHNOS formula classes) than in full scan mode. The number of detected highly polar NOM compounds (with elemental ratios H/C < 1, O/C > 0.6) were more than 20 times larger for CG-LC mode as compared to direct infusion (DI) (5715 vs 266 MF).We conclude that the new CG-LC-FT-ICR MS method achieved a novel insight into the highly polar fractions of NOM, which are inaccessible in conventional DI measurements.Key words: Natural organic matter (NOM), online LC-FT-ICR MS method, CASI mode, ESI&#160;

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PHYTOCHEMICAL SCREENING, ANTIOXIDANT, ANTI-CYTOTOXIC AND ANTICANCER EFFECTS OF GALINSOGA PARVIFLORA AND VERNONIA POLYANTHES (ASTERACEAE) EXTRACTS

International Journal of Research -GRANTHAALAYAH ◽

10.29121/granthaalayah.v8.i10.2020.1782 ◽

2020 ◽

Vol 8 (10) ◽

pp. 84-98

Author(s):

Sula M. V. Feleti ◽

Renê L. Aleluia ◽

Suiany V. Gervásio ◽

Jean Carlos V. Dutra ◽

Jessica R. P. Oliveira ◽

...

Keyword(s):

Fatty Acids ◽

Phenolic Acids ◽

Unsaturated Fatty Acids ◽

Biological Effects ◽

Human Lymphocytes ◽

Chemical Characterization ◽

Total Content ◽

Ags Cells ◽

Ft Icr Ms ◽

Ft Icr

The study was designed to investigate the chemical composition and the biological effects of G. parviflora and V. polyanthes ethanolic extracts in vitro. Total content of phenols, flavonoids and tannins was quantified by spectrophotometry; chemical characterization was permed by mass spectrometry (ESI (-) FT-ICR MS and APCI (+) FT-ICR MS analysis). Antioxidant activities were determined by FRAP and Fe2+ chelating methods. Extracts cytotoxicity was evaluated in human lymphocytes, sarcoma-180 (S-180) and human gastric adenocarcinoma (AGS) cells, by MTT assay. V. polyanthes presented higher total content of tannins and G. parviflora presented higher amount of phenols and flavonoids. Chemical characterization showed the presence of flavonoids, phenolic acids and sesquiterpene lactones in V. polyanthes extract, and steroids, phenolic acids and fatty acids (Poly Unsaturated Fatty Acids - PUFA) in G. parviflora extract. V. polyanthes extract stood out in the Fe2+ chelation test. G. parviflora extract did not present outstanding antioxidant results in the tested protocols. Both species showed a tendency to promote cytotoxicity in human lymphocyte cells. Regarding the antiproliferative effect, both species were able to reduce S-180 cell viability and G. parviflora extract showed high antiproliferative potential in the assay with AGS cells. These findings reinforce the medicinal use of these plants, as well as suggest their potential use for the development of new drugs and for the treatment of cancers.

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