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Sediment samples along a transect extending from the Mississippi River Birdsfoot Delta to the Mississippi Canyon on the Louisiana continental shelf were examined, by advanced analytical techniques, electrospray ionization coupled to a 12T Fourier transform ion cyclotron resonance mass spectrometer (ESI-FTICR-MS) and quantitative solid-state multiple cross polarization magic angle spinning (multi-CPMAS) 13C NMR, in an effort to understand the source and export of terrigenous organic matter to the Gulf of Mexico. Both NMR and mass spectral data indicate that condensed aromatics (CA) and carboxyl-containing aliphatic molecules (CCAM) are present at the mouth of the river, reflective of high contributions from terrigenous soil-like organic matter. Mass spectral peak magnitudes of CA diminish by 15%, with increasing distance offshore, and represent 30% of integrated NMR peak areas. In contrast, mass spectral and NMR CCAM peaks increase by 7 and 13%, respectively. These trends in humic acid extracts, provide novel molecular evidence of terrigenous organic matter deposition in offshore sediments.

Background Urine drug testing (UDT) is a standard practice used for monitoring controlled and illicit substances in ambulatory care patients. Point-of-care (POC) UDTs are useful tools that allow for drug identification within minutes, providing rapid and objective diagnostic assistance for clinicians. The objective of this study was to evaluate the performance characteristics of 3 different POC UDT devices compared to reference methods. Methods A total of 106 residual urine specimens were collected to evaluate the 3 POC UDT devices: the Profile®-V MEDTOX Scan® drugs of abuse test, Quidel Triage® TOX Drug screen, and Quidel Triage Rapid OXY-BUP-MDMA panel. Device performance was assessed by their ability to identify drug classes/compounds compared to manufacturer and reference method (mass spectrometry) cutoffs. Results The results from quantitative mass spectrometry showed that 77% (84/106) of the samples were positive for one or more drugs. Each device had variable performance across each drug class. Overall, the specificity of the Profile-V MEDTOX Scan test was 90.1%, while the Quidel Triage TOX Drug Screen and Rapid OXY-BUP-MDMA devices had specificities of 89.0% and 50.0% using their respective manufacturer-stated cutoffs. Overall sensitivity was determined to be 98.6%, 97.0%, and 100% for the Profile-V MEDTOX Scan, Quidel Triage TOX Drug Screen, and Rapid OXY-BUP-MDMA, respectively. Conclusions Of the 3 POC UDT devices evaluated, the Profile-V MEDTOX Scan demonstrated the best overall sensitivity and specificity compared to reference methods. False positive and negative results are possible with UDTs, ultimately the best device may depend on patient population and drugs of interest.

NMR spectroscopy is widely used in the field of aquatic biogeochemistry to examine the chemical structure of dissolved organic matter (DOM). Most aquatic DOM analyzed by proton NMR (1 H NMR) is concentrated mainly by freeze-drying prior to analysis to combat low concentrations, frequently

Following the Deepwater Horizon oil spill in the Gulf of Mexico, natural marine snow interacted with oil and dispersants forming marine oil snow (MOS) that sank from the water column to sediments. Mesocosm simulations demonstrate that Macondo surrogate oil incorporates into MOS and can be isolated, extracted, and analyzed via Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). Up to 47% of the FTICR-MS signal from MOS extracts can be attributed to formulas also found in Macondo surrogate oil demonstrating extensive oil incorporation. Additionally, oxygenation patterns for MOS extracts provide evidence for degraded oil compounds. Formulas having similar double bond equivalents but higher oxygen content (MOS CHO: CHO2-9, DBE2-16, MOS CHON: CHO0-7N1, DBE9-18; Macondo CHO: CHO1-4, DBE2-15, CHON: CHO0-3N1, DBE9-21) were found in MOS extracts generating isoabundance distributions similar to those of environmentally aged oil. Such shifts in molecular composition are consistent with the transformation of high DBE oil components, unobservable by FTICR-MS until oxygenation in the mesocosms. Low light conditions and the rapid proliferation of hydrocarbon-degraders observed in parallel studies suggest biological activity as the primary cause of oil degradation. MOS may thus represent an important microenvironment for oil degradation especially during its long transit below the euphotic zone to sediments.

Reactive oxygen species (ROS) are thought to play an important, although poorly understood, role in modifying the composition of terrigenous-derived dissolved organic matter (tDOM) upon export to aquatic systems. Of the dominant ROS in natural systems, OH has been shown to substantially modify lignin under laboratory conditions, simulating processes responsible for transformation of DOM in natural waters. Utilizing high performance liquid chromatography (HPLC) in conjunction with ultrahigh resolution mass spectrometry, we examined HPLC fractionated lignin extracts in an effort to establish which fractionated components of the lignin extract were (i) most susceptible to attack by OH and (ii) most likely to be responsible for compounds observed in the DOM. The results indicate that the most polar components of the lignin extract, representing tDOM, could be responsible for a large portion of newly generated formulas observed within DOM in natural waters. This suggests that partially oxidized lignin may be readily altered to compounds observed in DOM which are not typically associated with terrigenous OM, such as alicyclic and condensed aromatic-like compounds.

Evidence suggests that reactive oxygen species (ROS) are important in transforming the chemical composition of the large pool of terrestrially-derived dissolved organic matter (DOM) exported from land to water annually. However, due to the challenges inherent in isolating the effects of individual ROS on DOM composition, the role of ROS in the photochemical alteration of DOM remains poorly characterized. In this work, terrestrial DOM was independently exposed to singlet oxygen (1O2), and superoxide ( O 2 - under controlled laboratory conditions). Using ultra-high resolution mass spectrometry to track molecular level alterations of DOM by ROS, these findings suggest exposure to 1O2 (generated using Rose Bengal and visible light) removed formulas with an O/C > 0.3, and primarily resulted in DOM comprised of formulas with higher oxygen content, while O 2 - exposure (from KO2 in DMSO) removed formulas with O/C 1.5). Comparison of DOM altered by ROS in this study to riverine and coastal DOM showed that (20–80%) overlap in formulas, providing evidence for the role of ROS in shaping the composition of DOM exported from rivers to oceans.

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NMR spectroscopy is widely used in the field of aquatic biogeochemistry to examine the chemical structure of dissolved organic matter (DOM). Most aquatic DOM analyzed by proton NMR (

During the past decade, Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) has been established as a technique of choice for the comprehensive chemical assessment of some of the most complex organic mixtures, such as petroleum, or dissolved organic matter. In the aftermath of the Deepwater Horizon (DWH) blowout, FTICR-MS demonstrated its applicability for the characterization of oil spill residues produced by abiotic weathering, such as photooxidation, and/or microbial processes and interactions, for example, marine oil snow aggregation. Such residues are abundant in high molecular weight, polar, and heteroatom-bearing chemical species, which cannot be analyzed by the typical oil spill forensics tools such as gas chromatography. Therefore, the expansion of the analytical window afforded by FTICR-MS is crucial for the monitoring and understanding of long-term oil spill fate. Furthermore, capability of FTICR-MS to characterize non-hydrocarbon petroleum fractions will be very important in the case of potential future spills of heavy, unconventional oils, such as bitumen.

A novel method to rapidly methylate glycerol and generate products having greater value has been demonstrated using tetramethylammonium hydroxide (TMAH) thermochemolysis. Through analysis with GC–MS, it is shown that the reaction between TMAH and glycerol at elevated temperatures produces a series of mono, di and tri-methoxylated glycerols with potential applications as organic solvents. While other methylation reactions can only be carried out in batch reactions, thermally assisted methylation using TMAH can be performed in a continuous flow process.

Soil humic acids are the base soluble/acid insoluble organic components of soil organic matter. Most of what we know about humic acids comes from studies of their bulk molecular properties or analysis of individual fractions after extraction from soils. This work attempts to better define humic acids and explain similarities and differences for several soils varying in degrees of humification using advanced molecular level techniques. Our investigation using electrospray ionization coupled to Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) and nuclear magnetic resonance spectroscopy (NMR) has given new insight into the distinctive molecular characteristics of humic acids which suggest a possible pathway for their formation. Humic acids from various ecosystems, climate regions and soil textural classes are distinguished by the presence of three predominant molecular components: lignin-like molecules, carboxyl-containing aliphatic molecules and condensed aromatic molecules that bear similarity to black carbon. Results show that humification may be linked to the relative abundance of these three types of molecules as well as the relative abundance of carboxyl groups in each molecular type. This work also demonstrates evidence for lignin as the primary source of soil organic matter, particularly condensed aromatic molecules often categorized as black carbon and is the first report of the non-pyrogenic source for these compounds in soils. We also suggest that much of the carboxyl-containing aliphatic molecules are sourced from lignin.

Long-term stabilization of soil organic matter (SOM) plays an important role in the carbon cycle. Hence, understanding biogeochemical mechanisms of soil C sequestration is crucial to control its release to the atmosphere. This study aims at investigating the biogeochemical mechanisms of soil C sequestration. An exploratory assessment was carried out on the information about the soil C levels provided by the molecular composition of humic acids (HAs) analyzed by electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). Significant PLS forecasting model for total soil C was obtained using as descriptors the 131 compounds in common in all the HAs detected by FTICR-MS, and its variable importance for projection (VIP) was plotted in the space defined by their atomic ratios using van Krevelen diagrams. The results indicated that significant relationship exists between the HAs molecular composition and the soil organic C levels. The VIP values for the different groups of compounds illustrate how HA contains information about the amounts of C stored in the soil: the HAs in the soils with high levels of organic C have significantly (P < 0.1) higher proportions of unsaturated lipid and lignin-derived compounds; on the other side, low soil organic C levels are associated to HAs with comparatively high proportions of saturated lipid compounds., Financial support by Spanish CICyT (grant CGL2013-43845-P) is gratefully acknowledged. Marco A. Jiménez-González thanks the Spanish Ministry of Economy and Competitiveness (MINECO) for funding his pre-doctoral fellowship (BES-2014-069238).

Extracellular polymeric substances (EPS), produced by microorganisms , are implicated for greatly influencing the fate of environmental contaminants , including oil. Transparent exopolymeric particles (TEP) are gel-like acidic polysaccharide particles that can be stained with Alcian blue, whereas Coomassie stainable particles (CSP) contain proteins and are stained with Coomassie brilliant blue. Marine microgels are reversibly formed from EPS. These terms are often used interchangeably, but they have rarely been measured simultaneously. Mesocosm and bottle experiments provided an opportunity to compare EPS, TEP, CSP and microgels in a water-accommodated fraction (WAF) of oil and seawater (control). Our results reveal that the biopolymers making up EPS, TEP and CSP consisted primarily of polysaccharides and proteins, mostly likely as proteoglycans and glycoproteins . Significant correlations were found between concentrations of TEP-C vs particulate organic carbon (POC), TEP-C vs particulate organic nitrogen (PON), TEP vs EPS, TEP vs CSP, TEP vs carbohydrates, proteins, CSP and carbohydrates, CSP vs proteins, and carbohydrates vs proteins. Chemical analysis of whole particles and colloids yielded both protein and polysaccharides concentrations higher than those in EDTA extraction, thus providing an upper limit of actual EPS contents in the particulate phase. The EPS that was electrostatically held onto particle surfaces (extractable by 1% EDTA) accounted for a minor (~4%) yet relatively constant proportion of TEP. Overall, the concentrations of the three terms ranked in the order of [gels] > [TEP] > [particulate EPS] in the water. Lastly, spectrophotometric methods have limitations in identifying complex or refractory polysaccharides, as evidenced by the comparison between NMR-quantified EPS and the total EPS determined by spectrophotometric methods. This study is the first time these terms were compared in the same sample. They provide useful information when reviewing historical TEP, CSP, EPS data collected field- and laboratory-studies, and provide linkages between them. In addition, they also demonstrate that they could provide complementary information relevant to ecosystem and flux studies.

9 páginas.-- 7 figuras.-- 2 tablas.-- 65 referencias.-- Supplementary data related to this article can be found at https://doi.org/10.1016/j.jenvman.2018.07.069., Fire is one of the most important modulating factors of the environment and the forest inducing chemical and biological changes on the most reactive soil component, the soil organic matter (SOM). Assuming the complex composition of the SOM, we used an ultra-high resolution mass spectrometry analysis technique to assess the chemical composition and fire-induced alterations in soil particle size fractions (coarse and fine) from a sandy soil in a Mediterranean oak forest at Doñana National Park (Southwest Spain). Electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) showed that the coarse fraction of soils not affected by fires consisted mainly of polyphenolic compounds consistent with little-transformed SOM and fresh biomass, whereas the fine fraction was enriched in protein and lipid like homologues suggesting microbially reworked SOM. In fire-affected SOM, the coarse fraction contained a high proportion of aromatic compounds, consistent with inputs of charred litter or in situ chemical transformation of the SOM. Analysis of the fine fraction revealed two differentiated chemical families pointing to the existence of two carbon pools; a native microbial-derived moiety composed of lipids and polypeptide compounds, and a secondary, pyrogenic or thermally-altered moiety rich in aromatic compounds. This work represents the first application of ultra-high resolution mass spectrometry to study the chemical composition of SOM in different particle size fractions., The authors wish to thank MINECO project INTERCARBON (CGL2016-78937-R), and the Department of Chemistry and Biochemistry of the Old Dominion University (Norfolk, VA, USA) that provided access to the analytical facilities of the College of Science Major Instrumentation Cluster (COSMIC). Access to sampling sites and the logistics on-site was provided by project “Soil Carbon Turnover and Fluxes in Mediterranean Natural and Managed Ecosystems” (2017/19). NT Jiménez-Morillo is funded by FPI research grant (BES-2013-062573). N.T. Jiménez-Morillo is thanked for the preparation of the supplementary materials. JM de la Rosa thanks MINECO for funding his “Ramon y Cajal” contract.

Exposure of lignin-derived organic matter (OM) to hydroxyl radicals originating from Fenton type reactions generates condensed aromatic and alicyclic aliphatic compounds, as shown using ultrahigh resolution mass spectrometry. Although condensed aromatic compounds are common in soil and dissolved OM, their presence has been attributed largely to combustion. A non-pyrogenic route for the formation of condensed aromatic compounds from lignin is suggested here, specifically that hydroxyl radical-initiated oxidation of lignin is capable of producing black carbon-like condensed aromatic compounds. Alicyclic aliphatic compounds are also produced, likely as part of a concerted process involving ring opening, polymerization and/or cyclization and hydrogen abstraction. Hydroxyl radicals associated with lignin degradation are produced through photochemistry in aqueous systems and enzymatic microbial processes in soil.