Atmospheric Organic Matter

Advanced solid-state NMR spectroscopy of natural organic matter

“…Therefore, solid-state NMR is essential for providing relatively complete structural information on atmospheric organic matter. Interested readers are strongly encouraged to consult two recent comprehensive reviews by Duarte and Duarte [250,251] on the application of NMR spectroscopy in atmospheric organic matter. To the best of our knowledge, there are only a small number of studies using solid-state NMR to characterize atmospheric organic matter (see below).…”

Investigating the water-soluble organic functionality of urban aerosols using two-dimensional correlation of solid-state 13C NMR and FTIR spectral data

“…Organic aerosols (OA) comprise a multitude of molecular structures, physical properties, and sources (primary and secondary formation) (P€ oschl, 2005;Duarte and Duarte, 2013). This inherent complexity constitutes a major obstacle to an improved understanding of OA chemistry and composition, but also to predict how OA affect the climate system, atmospheric processes, and human health (P€ oschl, 2005;Jurado et al, 2008;Heal et al, 2012).…”

Multidimensional Analytical Characterization of Water-Soluble Organic Aerosols: Challenges and New Perspectives

“…Although intuitively, the analysis in liquid-state of the water-soluble OA could make more sense, 1D solid-state CP-MAS 13 C NMR presents some advantages for the analysis of this fraction, especially when compared to 1D liquid-state 1 H NMR spectroscopy or even to 1D liquid-state 13 C NMR spectroscopy. Some of these advantages have been reviewed by Duarte and Duarte [24,69] and include: the solid-state technique is not affected by the solvent, which can cause changes in the chemical shifts of the sample, hide some sample chemical resonances by the solvent signals, or even loss of some peaks, namely those of the carboxylic acids, due to the presence of rapidly exchangeable protons; the liquid-state NMR spectra may present lower resolution and sensitivity due to the low solubility of some organic components in the selected solvent, and the solid-state technique is a non-destructive method, allowing the sample to be used for further complementary structural analysis. On the other hand, [32]; rural OA [39]; aged urban OA obtained from Cleveland et al [38]; fresh pollen obtained from Chalbot et al [41]; and fresh emissions from BBOA obtained from Chalbot et al [65].…”

“…On the other hand, a major limitation of the solid-state CP-MAS 13 C NMR technique is the difficulty in obtaining high-quality NMR spectra due to the relatively low carbon content of ambient water-soluble OA samples. This fact requires combining several aerosol samples collected under a common feature (e.g., similar ambient conditions) in order to obtain a sufficient amount of sample for analysis (it needs~20-100 mg of sample, depending on the size of the NMR probe) [69]. Furthermore, to make the sample amenable to CP-MAS 13 C NMR analysis, the organic material must be isolated from the inorganic ions (e.g., through solid-phase extraction, ion-exchange chromatography, or size-exclusion chromatography) and prepared as a solid (e.g., freeze-drying) prior to analysis [69].…”

“…This fact requires combining several aerosol samples collected under a common feature (e.g., similar ambient conditions) in order to obtain a sufficient amount of sample for analysis (it needs ~20-100 mg of sample, depending on the size of the NMR probe) [69]. Furthermore, to make the sample amenable to CP-MAS 13 C NMR analysis, the organic material must be isolated from the inorganic ions (e.g., through solidphase extraction, ion-exchange chromatography, or size-exclusion chromatography) and prepared as a solid (e.g., freeze-drying) prior to analysis [69]. It must be emphasized, however, that under these circumstances, the acquisition of a high-quality 13 C NMR spectrum is made at the expense of pursuing studies on near real-time variations of the chemical composition of OA.…”