Expanding the Analytical Window for Biochar Speciation: Molecular Comparison of Solvent Extraction and Water-Soluble Fractions of Biochar by FT-ICR Mass Spectrometry

Author(s):  
Amy M. McKenna ◽  
Martha L. Chacón-Patiño ◽  
Huan Chen ◽  
Gregory T. Blakney ◽  
Frederic Mentink-Vigier ◽  
...  
2012 ◽  
Vol 9 (3) ◽  
pp. 285 ◽  
Author(s):  
Lynn R. Mazzoleni ◽  
Parichehr Saranjampour ◽  
Megan M. Dalbec ◽  
Vera Samburova ◽  
A. Gannet Hallar ◽  
...  

Environmental contextAerosol water-soluble organic carbon is a complex mixture of thousands of organic compounds which may have a significant influence on the climate-relevant properties of atmospheric aerosols. Using ultrahigh resolution mass spectrometry, more than 4000 individual molecular formulas were identified in non-urban aerosol water-soluble organic carbon. A significant fraction of the assigned molecular formulas were matched to assigned molecular formulas of laboratory generated secondary organic aerosols. AbstractWater-soluble organic carbon (WSOC) is a complex mixture of thousands of organic compounds which may have significant influence on the climate-relevant properties of atmospheric aerosols. An improved understanding of the molecular composition of WSOC is needed to evaluate the effect of aerosol composition upon aerosol physical properties. In this work, ultrahigh-resolution Fourier transform–ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterise aerosol WSOC collected during the summer of 2010 at the Storm Peak Laboratory (3210 m ASL) near Steamboat Springs, CO. Approximately 4000 molecular formulas were assigned in the mass range of 100–800 Da after negative-ion electrospray ionisation and more than 50 % of them contained nitrogen or sulfur. The double bond equivalents (DBEs) of the molecular formulas were inversely proportional to the O : C ratio, despite a relatively constant H : C ratio of ~1.5. Despite the range of DBE values, the elemental ratios and the high number of oxygen atoms per formula indicate that a majority of the compounds are aliphatic to olefinic in nature. These trends indicate significant non-oxidative accretion reaction pathways for the formation of high molecular weight WSOC components. In addition, a significant number of molecular formulas assigned in this work matched those previously identified as secondary organic aerosol components of monoterpene and sesquiterpene ozonolysis.


2019 ◽  
Author(s):  
Jiao Tang ◽  
Jun Li ◽  
Tao Su ◽  
Yong Han ◽  
Yangzhi Mo ◽  
...  

Abstract. We investigated the fluorescence and chemical-structural characteristics of dissolved brown carbon (BrC) in smoke particulates emitted from the combustion of biomass and fossil fuels (coal and vehicle exhaust) by excitation-emission matrix (EEM) spectroscopy and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) coupled with electrospray ionization (ESI). Six components were resolved by parallel factor analysis (PARAFAC) of the water-soluble and methanol-soluble organic carbon (MSOC) fractions, respectively. These fluorescent components varied among sources. Combined with FT-ICR MS ion groups, we found that the fluorescent components agreed well with the functional groups, particularly with nitrogen (N)- and sulfur (S)-containing groups. Among the six PARAFAC components (P1–6) retrieved from the water-soluble organic carbon (WSOC) fraction, except for the P3 component, the other components exhibited different values among the three types of emission sources tested. Vehicle exhaust was characterized by high P1 and P6 components, which are mainly associated with aromatic organosulfate compounds, and a high P5 component, mainly associated with sulfonates; coal combustion was characterized by a high P4 component, which is associated with nitrooxy-organosulfate (nitrooxy-OS) compounds; and biomass burning was characterized by the P2 component. Similar results were observed in the case of the MSOC fraction. This study reveals the source contribution and possible structures of previously unclear excitation-emission matrix (EEM) fluorescent components in combustion-derived aerosols. These are the first findings of this type and are potentially applicable to further studies on EEM-based source apportionment of dissolved BrC in aerosols.


2020 ◽  
Author(s):  
Ian Sims ◽  
CJ Pollock ◽  
R Horgan

Individual fructan tri-, tetra- and pentasaccharide isomers in neutral, water-soluble extracts from Lolium temulentum were purified and the linkages present in these isomeric oligosaccharides were analysed by combined GC-mass spectrometry of partially methylated alditol acetates. 1-Kestose and neokestose were the most abundant trisaccharides with 6-kestose present in much lower amounts. Analysis of isomers of DP 4 and 5 showed that multiple linkage types were present with structures based on all three trisaccharides. Oligosaccharides based on neokestose but with 2,6 linkages between adjacent fructose residues have not been previously detected in higher plants. © 1992.


Holzforschung ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Xiaodi Wang ◽  
Yongchao Zhang ◽  
Luyao Wang ◽  
Xiaoju Wang ◽  
Qingxi Hou ◽  
...  

AbstractAn efficient separation technology for hydrolysates towards a full valorization of bamboo is still a tough challenge, especially regarding the lignin and lignin-carbohydrate complexes (LCCs). The present study aimed to develop a facile approach using organic solvent extraction for efficiently fractionating the main components of bamboo hydrolysates. The high-purity lignin with only a trace of carbohydrates was first obtained by precipitation of the bamboo hydrolysate. The water-soluble lignin (WSL) fraction was extracted in organic solvent through a three-stage organic solvent extraction process, and the hemicellulosic sugars with increased purity were also collected. Furthermore, a thorough characterization including various NMR techniques (31P, 13C, and 2D-HSQC), GPC, and GC-MS was conducted to the obtained lignin-rich-fractions. It was found that the WSL fraction contained abundant functional groups and tremendous amount of LCC structures. As compared to native LCC of bamboo, the WSL fraction exhibited more typical LCC linkages, i.e. phenyl glycoside linkage, which is the main type of chemical linkage between lignin and carbohydrate in both LCC samples. The results demonstrate that organic phase extraction is a highly efficient protocol for the fractionation of hydrolysate and the isolation of LCC-rich streams possessing great potential applications.


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