Nuclear Magnetic Resonance Analysis of Natural Organic Matter

Simpson, André J.; Simpson, Myrna J.

doi:10.1002/9780470494950.ch15

Cited by 18 publications

(16 citation statements)

References 261 publications

(472 reference statements)

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“…[12] Unfortunately, because of the sophistication of these 2D NMR techniques, atmospheric chemists who wish to apply them to OAs analysis may experience some difficulties in selecting the most appropriate 2D experiments for answering their specific question. In this regard, readers are referred to the excellent reviews of Simpson et al [28] and Simpson and Simpson [37] and references therein, where they can find suggestions as to the key 2D NMR experiments and pulse programs that may be useful for studying very complex natural organic mixtures.…”

Section: D Solution-state Nmr Studies Of Aerosol Wsommentioning

confidence: 99%

“…A more detail discussion on this issue, aimed at those interested in applying solution-state 2D NMR to atmospheric organic matter, is provided in the review works of Simpson et al [28] , and Simpson and Simpson [37] and references therein. At this point, it is clear that 2D NMR-based approaches place the identification of known organic species in atmospheric samples (OAs, rainwater, and fog water) early in the discovery line, simultaneously enabling the targeted isolation and assignment of unknown structures.…”

Section: D Solution-state Nmr Studies Of Aerosol Wsommentioning

confidence: 99%

“…As recently reviewed, [12] to establish and improve the quantitative behavior of this technique, a number of different approaches have been recommended, usually through optimization of NMR parameters, such as the rate of MAS, contact time, and recycle delay, so that 13 C nuclei in all carbon functional groups will be equally detected. Once again, readers are encouraged to consult the comprehensive reviews of Cook, [36] Simpson and Simpson, [37] and Conte et al [45] and references therein to obtain a more complete understanding of the recommended procedures to obtain the most possible quantitatively correct solid-state CP-MAS 13 C NMR spectra of natural organic matter. In the works published thus far focusing on OA and their water-soluble fractions, MAS frequencies range from 5 to 10 kHz, contact times are generally between 1 and 5 ms, and recycle delay times range from 1 to 5 s. In order to obtain a quantitatively correct CP-MAS 13 C NMR spectrum of aerosol WSOM, it is advisable to use a MAS rate of 10 kHz for reducing the number and intensity of spinning sidebands, [42] a contact time of 1.0 ms, [40] and a recycle delay of 5 s. [40] Even if the NMR equipment is properly set and spectra manipulation is not userdependent, the CP technique may still underestimate C NMR data also shows evidence that the WSOM from aerosols exhibit the same main carbon functional groups, but their relative abundances are quite different.…”

Section: à3mentioning

confidence: 99%

“…dimethyl sulfoxide-d 6 (DMSO-d 6 )). [37] As recently reviewed, [12] only one study has applied 1 H HR-MAS NMR, combined with solution-state and solid-state NMR methods, for studying the organic composition of surface films originated from atmospheric deposition in urban environments. [23] In comparison with solution-state 1 H NMR, the use of 1 H HR-MAS NMR alone provides less detail on the distribution of all protons in the sample, leading to an incomplete description of its components.…”

Section: H Hr-mas Nmr Spectroscopymentioning

confidence: 99%

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Unraveling the structural features of organic aerosols by NMR spectroscopy: a review

Duarte

2015

Magnetic Reson in Chemistry

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Our limited understanding of the effect of organic aerosols (OAs) on the climate and human health is largely because of the vast array of formation processes and sources that produce a multitude of molecular structures and physical properties. The need to unravel the enormous complexity and heterogeneity of OAs and thus understand their effects on the climate and human health has led to the development of different off-line methods based on the use of advanced analytical techniques. Within this context, nuclear magnetic resonance (NMR) spectroscopy has become essential for acquiring detailed structural characterization of the complex natural organic matter contained in atmospheric aerosols. In this article, we present a critical review on the application of NMR spectroscopy in OAs (primary and secondary) studies, focusing mainly on the water-soluble organic fraction, and how NMR has impacted our knowledge on atmospheric organic matter. A major emphasis is given on the wealth of chemical information that solid-state and multi-dimensional solution-state NMR can provide, including the sources, formation pathways, seasonal, and regional characterization of atmospheric OAs. Finally, major challenges are discussed and recommendations for future research directions are proposed.

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Section: D Solution-state Nmr Studies Of Aerosol Wsommentioning

confidence: 99%

Section: D Solution-state Nmr Studies Of Aerosol Wsommentioning

confidence: 99%

Section: à3mentioning

confidence: 99%

Section: H Hr-mas Nmr Spectroscopymentioning

confidence: 99%

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Unraveling the structural features of organic aerosols by NMR spectroscopy: a review

Duarte

2015

Magnetic Reson in Chemistry

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“…e aliphaticity degree was calculated as the sum of intensities in chemical shift area 0-105 ppm, while the aromaticity degree was calculated as the sum of the peaks in 105-165 ppm area [38][39][40][41]. …”

Section: Laboratory Methodsmentioning

confidence: 99%

Humification and Humic Acid Composition of Suspended Soil in Oligotrophous Environments in South Vietnam

Abakumov

Rodina

Eskov

2018

Applied and Environmental Soil Science

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Humification is considered to be a global process that is implemented in soils and organic sediments and also in natural water and air. e term "suspended soils" has become increasingly common in recent years. Suspended soils are defined as the part of the organic matter that has not undergone the full decomposition process and has not turned into the humus of terrestrial soils. Suspended soils were shown to contain higher total nitrogen, phosphorus, and potassium contents than the forest soil, but the moisture content in suspended soils was significantly lower. Our study of the structural composition of humic substances in suspended soils was conducted with an aim of evaluating the humification rates and structural composition of humic acids in the suspended soil in tropical forests of South Vietnam. Soil samples from three selected areas were investigated: the soil under phorophytes (mineral soil presented by samples of topsoil of the typical dry savanna landscape) and two soils from epiphytous formations. Samples were collected from savanna-type sparse communities, located on oligotrophous plains in Phú Quốc Island (South Vietnam) in 2015. General properties of the soil and the elemental composition of suspended soils were determined, and the humic substance chemical composition was evaluated using solid state 13 C-NMR. Data obtained showed that the pH of the soils under phorophytes was higher than in the suspended soils; basal respiration did not tend to change indices between soils under phorophytes and suspended soils, but the suspended soil was less enriched by nitrogen than the soil under phorophytes.is can be related to the total amount of organic matter exposed to humification in various soils and to the presence of an essential portion of mineral particles in the soil under phorophytes. Data on elemental composition of the humic acids (HAs) indicated that one method of humification is implemented in all three soils that were investigated. e humic acids of the phorophyte soil showed the same content of aromatic fraction as the suspended soil. e most comparable soil type in terms of humic substance composition is Cambisols from humid forests of subboreal and subtropical zones. e humification process implemented in suspended soils showed the absence of mineral compounds or mineral fine earth, which indicated that humification in conditions of pure organic substrates can result in formation of deep humified organic matter, as shown by humic acids with an essential aromatic fraction content.

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