Ionization Fourier Transform Ion Cyclotron Research Articles

Penetration Profile of Terbinafine Compared to Amorolfine in Mycotic Human Toenails Quantified by Matrix-Assisted Laser Desorption Ionization-Fourier Transform Ion Cyclotron Resonance Imaging.

Amorolfine 5% lacquer is an established topical treatment for fungal infection of the nails. The success of topical therapy for onychomycosis depends on whether the permeated drug concentration in the deep nail bed is retained above the effective antifungal minimum inhibitory concentration (MIC). We compared the penetration profile of amorolfine and a new topical formula of terbinafine in human mycotic toenails using matrix-assisted laser desorption ionization mass spectrometry imaging-Fourier transform ion cyclotron resonance (MALDI-FTICR) imaging. Amorolfine 5% lacquer and terbinafine 7.8% lacquer were applied to mycotic nails (n = 17); nail sections were prepared, and MALDI-FTICR analysis was performed. Based on the MICs of amorolfine and terbinafine needed to kill 90% (MIC90) of Trichophyton rubrum, the fold differences between the MIC90 and the antifungal concentrations in the nails (the multiplicity of the MIC90) were calculated overall and for the keratin-unbound fractions. Both amorolfine and terbinafine penetrated the entire thickness of the nail. The mean concentration across the entire nail section 3h following terbinafine treatment was 1414μg/g of tissue (equivalent to 4.9mM) compared with 780μg/g (2.5mM) following amorolfine treatment (not significantly different; p = 0.878). The median multiplicity of the MIC90 was significantly higher in amorolfine- than terbinafine-treated nails overall (191 vs. 48; p = 0.010) and for the keratin-unbound fractions only (7.4 vs. 0.8; p = 0.002). In this ex vivo study, MALDI-FTICR demonstrated that, although amorolfine 5% and terbinafine 7.8% had similar distribution profiles, both penetrating from the surface to the nail bed, the concentration of amorolfine in the nail was significantly higher than that of terbinafine relative to their respective MIC90 values. Clinical studies are required to determine whether these effects translate to a clinical difference in treatment success.

Novel use of the electrocatalytic oxidation process with Fe-DSA dual anode configuration for leachate treatment: Significance of in situ ferrate generation

The leachate produced by waste transfer stations (WTSs) contains substantial amounts of refractory organic matter and ammonia, necessitating on-site treatment. In this study, a novel electrocatalytic oxidation (ECO) process with Fe-DSA dual anode configuration was established for leachate pretreatment. In this configuration, chloride in the leachate was converted to active chlorine by the DSA anode, while ferric hydroxide (Fe(OH)3) was produced from Fe anode. As a result, Fe (VI) was in situ formed through the reactions between active chlorine and Fe(OH)3. Simultaneous and efficient removal of COD and NH4+-N in the ECO process with Fe-DSA dual anode configuration was achieved, significantly improving leachate biodegradability compared with the Fe–Fe and DSA-DSA dual anode configurations. The transformation characteristics of organic compounds in the ECO process were investigated through the electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) analysis. The ECO process with Fe-DSA dual anode configuration promoted the removal and transformation of lignins/carboxylic rich alicyclic molecules (CRAM)-like and tannins compounds with biologically refractory properties, as well as S-containing compounds with biological toxicity. Further X-ray photoelectron spectroscopy (XPS) analysis revealed that iron oxides, amorphous Fe-(oxy) hydroxide, and amorphous Fe(OH)3 produced by Fe (VI) decomposition in the ECO process with Fe-DSA dual anode configuration enhanced removal performance through coagulation. In addition, the contribution of different active species to organic matter removal in the ECO process was quantified by quenching experiments. High-valent iron oxidation dominated the ECO process with Fe-DSA dual anode configuration, while active chlorine oxidation, •OH oxidation and coagulation synergistically contributed to organic matter removal.

Penetration Profiles of Four Topical Antifungals in Mycotic Human Toenails Quantified by Matrix-Assisted Laser Desorption Ionization-Fourier Transform Ion Cyclotron Resonance Imaging.

Onychomycosis is a fungal infection of the nails that can be challenging to treat. Here, matrix-assisted laser desorption ionization-Fourier transform ion cyclotron resonance (MALDI-FTICR) imaging was applied to the quantitative analysis of the penetration profile of the antifungal compound, amorolfine, in human mycotic toenails. The amorolfine profile was compared with those of three other antifungals, ciclopirox, naftifine, and tioconazole. Antifungal compounds (amorolfine 5% lacquer, ciclopirox 8% lacquer, naftifine 1% solution, and tioconazole 28% solution) were applied to mycotic nails (n = 42). Nail sections were prepared, and MALDI-FTICR analysis was performed on the sections at a spatial resolution of 70 μm to compare the distribution profiles. Based on the minimum inhibitory concentrations of the four test compounds needed to kill 90% (MIC90) of the fungal organism, Trichophyton rubrum, the fold differences between the MIC90 and the antifungal concentrations in the nails (termed the multiplicity of the MIC90) were calculated for each. The penetration profiles indicated higher concentrations of amorolfine and ciclopirox in the deeper layers of the nails 3h after treatment, compared with naftifine and tioconazole. The mean concentrations across the entire nail sections at 3h were significantly different among the four antifungals: amorolfine, 2.46mM; ciclopirox, 0.95mM; naftifine, 0.63mM; and tioconazole, 1.36mM (p = 0.016; n = 8 per compound). The median multiplicity of the MIC90 at 3h was 191-fold for amorolfine, tenfold for ciclopirox, 52-fold for naftifine, and 208-fold for tioconazole. In this study, MALDI-FTICR was successfully applied to the quantitative analysis of antifungal distribution in human mycotic nails. The findings suggest that amorolfine penetrates deeper layers of the nail and accumulates at concentrations far exceeding the MIC needed to exert antimycotic activity.

High throughput identification of carbonyl compounds in natural organic matter by directional derivatization combined with ultra-high resolution mass spectrometry

Carbonyl compounds are important components of natural organic matter (NOM) with high reactivity, so that play a pivotal role in the dynamic transformation of NOM. However, due to the lack of effective analytical methods, our understanding on the molecular composition of these carbonyl compounds is still limited. Here, we developed a high-throughput screening method to detect carbonyl molecules in complex NOM samples by combining chemical derivatization with electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR-MS). In six different types of dissolved organic matter (DOM) samples tested in this study, 20%-30% of detected molecules contained at least one carbonyl group, with relative abundance accounted for 45% to 70%. These carbonyl molecules displayed lower unsaturation level, lower molecular weight, and higher oxidation degree compared to non-carbonyl molecules. More importantly, the measured abundances of carbonyl molecules were consistent with the results of 13C nuclear magnetic resonance (NMR) analysis. Based on this method, we found that carbonyl molecules can be produced at DOM-ferrihydrite interface, thus playing a role in shaping the molecular diversity of DOM. This method has broad application prospects in screening carbonyl compounds from complex mixtures, and the same strategy can be used to directional identification of molecules with other functional groups as well.

Structure and composition of dissolved organic matters in sludge by ultrasonic treatment

The leaching of dissolved organic matter (DOM) from the sludge into the liquid phase is induced by ultrasound. However, there is limited investigation into the structure and molecular composition of sludge DOM in this process. The molecular structure and composition of sludge DOM in ultrasonic treatment were comprehensively elucidated in this study. The sludge dissolved organic carbon (DOC) and three-dimensional fluorescence spectroscopy (3D-EEM) image had most significant change at 15-min ultrasonic time and 1.2 W/mL ultrasonic density, respectively. Gas Chromatography-Mass Spectrometry (GC-MS) analysis indicated that ultrasonic treatment of sludge reduced the macromolecules to small molecules in DOM. Then, electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (ESI FT-ICR-MS) analysis revealed that lignin, tannins, and carbohydrates were the main components of sludge DOMs after ultrasound treatment. analysis revealed that lignin, tannins, and carbohydrates were the main components of sludge DOMs after ultrasound treatment. Furthermore, through the Van Krevelen analysis, the major components were CHO (48.50%) and CHOS (23.20%) in the DOM of ultrasonicated sludge. This research provides the basis for the practical application of ultrasonic treatment of sludge and provides basic information for DOM components.

Molecular transformations of heteroatomic organic compounds in crude oils caused by biodegradation and subsequent thermal maturation: Insights from ESI FT-ICR MS

The Tarim and Junggar basins are major petroliferous sedimentary deposits in China. Some oil reservoirs in these basins experienced superimposed secondary alterations including early biodegradation followed by thermal maturation/alteration (SSA-B&M). Heteroatomic polar organic compounds in crude oil are significantly influenced by SSA-B&M, which play a vital role in understanding the evolutionary history of oil reservoir. However, research on such alterations is limited. The present study employed negative and positive ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to investigate the molecular transformations of heteroatomic organic compounds in crude oils resulting from SSA-B&M. The findings indicate that biodegradation leads to an enrichment of naphthenic acids, while subsequent cyclization, aromatization and thermal cracking reactions enhances the aromaticity of the pyrolysis products of all the oil samples with varying degree of biodegradation. Notably, highest aromaticity was observed for the crude oil that has been most severely altered by biodegradation. During early and moderate stages of biodegradation, the abundances of O2 compounds (molecules contain two oxygen atoms) representing carboxylic acids were continuously increasing. However, at severe biodegradation levels, fatty acids with 1 double bond equivalents (DBE) underwent degradation, while the naphthenic acids were further enriched. Subsequently, during maturation, O2 compounds with 1 to 5 DBE experienced a steady decline in abundance. The naphthenic acids mainly experienced aromatization, while the fatty acids were partly decarboxylized and cracked thereby forming new n-alkanes. Biodegradation led to modification in neutral nitrogen compounds with 3 to 4 condensed rings (DBE = 9–12) and long alkyl side chains, while the impact on basic nitrogen compounds was relatively minimal. After subsequent thermal maturation, both neutral and basic nitrogen compounds with long alkyl side chains underwent cracking, while those with shorter alkyl side chains and higher degrees of condensation tended to remain relatively unchanged. Finally, two new indices were defined and tested to correctly evaluate the maturation and biodegradation level for crude oils that have experienced SSA-B&M.

Photolysis of Dissolved Organic Matter over Hematite Nanoplatelets.

Solar photoexcitation of chromophoric groups in dissolved organic matter (DOM), when coupled to photoreduction of ubiquitous Fe(III)-oxide nanoparticles, can significantly accelerate DOM degradation in near-surface terrestrial systems, but the mechanisms of these reactions remain elusive. We examined the photolysis of chromophoric soil DOM coated onto hematite nanoplatelets featuring (001) exposed facets using a combination of molecular spectroscopies and density functional theory (DFT) computations. Reactive oxygen species (ROS) probed by electron paramagnetic resonance (EPR) spectroscopy revealed that both singlet oxygen and superoxide are the predominant ROS responsible for DOM degradation. DFT calculations confirmed that Fe(II) on the hematite (001) surface, created by interfacial electron transfer from photoexcited chromophores in DOM, can reduce dioxygen molecules to superoxide radicals (•O2-) through a one-electron transfer process. 1H nuclear magnetic resonance (NMR) and electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) spectroscopies show that the association of DOM with hematite enhances the cleavage of aromatic groups during photodegradation. The findings point to a pivotal role for organic matter at the interface that guides specific ROS generation and the subsequent photodegradation process, as well as the prospect of using ROS signatures as a forensic tool to help interpret more complicated field-relevant systems.

Polyphenols, Antioxidants, and Wound Healing of Lecythis pisonis Seed Coats.

To better use the Lecythis pisonis Cambess. biomass, this study investigates whether Sapucaia seed coats present wound healing properties. We analyzed the antibacterial, antioxidant, and wound healing-promoting potentials, plus cytotoxicity and stimulation of vascular endothelial growth factor-A. The chemical composition was analyzed by positive ion mode electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. A total of 19 compounds were identified, such as proanthocyanidin A1, procyanidins A1, B2, and C1, epigallocatechin, and kaempferol (p-coumaroyl) glycoside. Potent antioxidant strength/index was verified for 2,2-diphenyl-1-picrylhydrazyl radical (IC50 = 0.99 µg/mL) and ferric reducing antioxidant power (IC50 = 1.09 µg/mL). The extract did not present cytotoxicity and promoted significant cell migration and/or proliferation of fibroblasts (p < 0.05). Vascular endothelial growth factor-A was stimulated dose-dependently at 6 µg/mL (167.13 ± 8.30 pg/mL), 12.5 µg/mL (210.3 ± 14.2 pg/mL), and 25 µg/mL (411.6 ± 29.4 pg/mL). Platelet-derived growth factor (PDGF) (0.002 µg/mL) was stimulated at 215.98 pg/mL. Staphylococcus aureus was susceptible to the extract, with a minimum inhibitory concentration of 31.25 µg/mL. The identified compounds benefit the antioxidant activity, promoting hemostasis for the wound healing process, indicating that this extract has the potential for use in dermatological cosmetics.

Applying a risk assessment guided evaluation for verifying comprehensive two-dimensional gas chromatography to analyse complex pharmaceuticals

The reliability of analytical results is critical and indispensable when applied in regulated environments such as the pharmaceutical industry. Therefore, analytical workflows must be validated. However, validation guidelines are often designed for quantitative targeted analysis and rarely apply to qualitative untargeted approaches. In this study, we employ a risk assessment approach to identify critical parameters which might influence the qualitative results derived by online derivatisation — comprehensive two-dimensional gas chromatography coupled to a high-resolution time-of-flight mass spectrometer (GC × GC-HR-ToF–MS) for the analysis of the active pharmaceutical ingredient (API) sodium bituminosulfonate (SBS). To show the complexity and feasibility of such an approach, we focus on investigating three potential risk factors: sample preparation, vapourability, and the thermal stability of sulfonates. Through the individual evaluation of these potential risk factors due to the application of sample preparation approaches and thermal gravimetric analysis (TGA), we demonstrate the high derivatisation efficiency and repeatability of the online derivatisation method and confirm the absence of derivatisation-induced side reactions. In addition, we also show the potential thermal instability of an incompletely derivatised API. To address the limitation of these individual assessments, we applied a holistic evaluation step with negative electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry (ESI( −) FT-ICR MS) as an orthogonal technique. This confirms that most of the API is detected via the presented GC-based method. Thereby, we demonstrated the practical feasibility of the risk assessment-based approach to ensure the validity of the qualitative data for a complex untargeted method.Graphical

Morphology study of nickel and vanadium in asphaltenes via hydropyrolysis

The morphology of nickel and vanadium compounds in the asphaltenes were investigated via hydropyrolysis with the help of inductively coupled plasma mass spectrometer (ICP-MS), ultraviolet-visible (UV-Vis), high-temperature gas chromatography atomic emission detection (HT GC-AED), and positive-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (+ESI FT-ICR MS). The results showed that the toluene soluble yields of products decreased from 64% to 19% as the hydropyrolysis temperature increased from 330 to 410 °C, while the abundance of nickel and vanadium compounds detected by GC-AED increased significantly. The molecular composition distribution of nickel and vanadyl porphyrins showed rhythmic changes with different temperatures in the hydropyrolysis of asphaltenes.

Molecular comparison of organic matter removal from shale gas flowback wastewater: Ozonation versus Fenton process

Shale gas extraction process generates a large amount of shale gas flowback wastewater (SGFW) containing refractory organic compounds, which can pose serious environmental threats if not properly treated. However, the extremely complex compositions of organics in SGFW are still unknown and their transformation pathways in O3- and •OH-dominated systems are not well recognized, which restrain the selection of treatment technology and optimization of operational parameters. The removal characteristics and reaction mechanism of dissolved organic matter (DOM) in SGFW treated by ozonation and Fenton processes were comparatively investigated using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The results showed that both processes could degrade low-oxygen highly unsaturated and phenolic organics, polyphenolics and polycyclic aromatics, and transform them into aliphatic organics and high-oxygen highly unsaturated and phenolic organics. With increasing action of reactive oxygen species (O3 for ozonation and •OH for Fenton process), the degradation products (mainly aliphatic organics) increased during ozonation. However, in Fenton process, a wider range of DOM was removed without aliphatic organics accumulation. The degradation mechanisms of DOM during ozonation and Fenton processes included oxygen addition reactions (+3O, +H2O2, and +2O) as dominant pathways. However, ozonation showed more violent oxygenation, hydroxylation, and carboxylation, while Fenton process presented more violent chain-breaking reactions. These results revealed the selective oxidation of ozone and nonselective oxidation of •OH during SGFW treatment, and provided theoretical support for selecting SGFW treatment approaches.

Pretreatment with Trichoderma sp. AH promotes directional conversion of organic nitrogen compounds in supercritical methanolysis of wheat straw

The specificity and conversion of supercritical methanolysis of wheat straw (WS) and rice straw (RS) can be enhanced by Pretreatment using Trichoderma sp. AH, particularly the esters of the methanol-soluble portion (MSP) of WS and RS in supercritical methanolysis. However, only about 100 organic compounds of lower volatility and polarity could be detected in MSP by gas chromatography-mass spectrometry. Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry was used to determine the organic nitrogen compounds (ONCs) in the MSPs from supercritical methanolysis of raw and pretreated WS with Trichoderma sp. AH. The most prevalent ONCs in the MSPs of native and pretreated WSs in the positive ion mode would be N2On (n = 1–9) species having twin-bonding equivalence values (2–25) together with carbon-atom numbers of 4–35. Peak prevalent ONC within prior-treated WS MSPs is N2O4, with the most abundant ONC in raw WS MSPs is N2O5. These results help to understand the impact of Trichoderma sp. AH pretreatment upon converting ability/specificity for ONCs within WS methanolysis and employing MSP in producing jet fuel.

Mechanistic Insights into the Biodegradation of Carbon Dots by Fungal Laccase.

While carbon dots (CDs) have the potential to support the agricultural revolution, it remains obscure about their environmental fate and bioavailability by plants. Fungal laccase-mediated biotransformation of carbon nanomaterials has received little attention despite its known capacity to eliminate recalcitrant contaminants. Herein, we presented the initial investigation into the transformation of CDs by fungal laccase. The degradation rates of CDs were determined to be first-order in both substrate and enzyme. Computational docking studies showed that CDs preferentially bonded to the pocket of laccase on the basal plane rather than the edge through hydrogen bonds and hydrophobic interactions. Electrospray ionization-Fourier transform-ion cyclotron resonance mass spectrometry (ESI-FT-ICR MS) and other characterizations revealed that the phenolic/amino lignins and tannins portions in CDs are susceptible to laccase transformation, resulting in graphitic structure damage and smaller-sized fragments. By using the 13C stable isotope labeling technique, we quantified the uptake and translocation of 13C-CDs by mung bean plants. 13C-CDs (10 mg L-1) accumulated in the root, stem, and leaf were estimated to be 291, 239, and 152 μg g-1 at day 5. We also evidenced that laccase treatment alters the particle size and surface chemistry of CDs, which could facilitate the uptake of CDs by plants and reduce their nanotoxicity to plants.

Phytochemical profile of petals from black Dahlia pinnata by flow injection analysis-electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry.

Dahlia pinnata Cav. is a flower native to Mexico that has many applications; in particular, its petals have been used for ornamental, food, and medicinal purposes, for example to treat skin rashes and skin cracks. It has been reported that the medicinal properties of plants are generally related to the phytochemical constituents they possess. However, there are few studies on black D. pinnata. The present study was aimed at qualitatively and quantitatively determining the phytochemical profile of petals from black D. pinnata. Phytochemicals from Dahlia petals were extracted by consecutive maceration (hexane, dichloromethane, and methanol); then, the extracts were analyzed through colorimetric assays and UV-Vis spectroscopy for qualitative identification and quantification of phytochemical compounds, respectively. The methanolic extract was analyzed by flow injection analysis-electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (FIA-ESI-FTICR-MS) in negative and positive mode. Quantitative phytochemical profiling of the methanolic extract by UV-Vis spectroscopy indicated high contents of phenolic compounds (34.35 ±3.59 mg EQ/g plant) and sugars (23.91 ±1.99 mg EQ/g plant), while the qualitative profiling by FIA-ESI-FTICR-MS allowed the tentative identification of several flavonoids and phenolic acids. Kaempferol-3-rutinoside, pelargonidin-3-(6″-malonylglucoside)-5-glucoside, rutin, kaempferol-3-(2″,3″-diacetyl-4″-p-coumaroylrhamnoside), and myricetin-3-(2‴-galloylrhamnoside) were the main compounds detected. The results expand our knowledge of the phytochemical constituents of petals from black D. pinnata.

Quantitative Approaches in Assessing Soil Organic Matter Dynamics for Sustainable Management

The aim of this study was to provide an overview of the approaches and methods used to assess the dynamics of soil organic matter (SOM). This included identifying relevant processes that describe and estimate SOM decomposition, lability, and humification for the purpose of sustainable management. Various existing techniques and models for the qualitative and quantitative assessment of SOM were evaluated to gain a better understanding of advances in organic matter transformation. This evaluation aimed to identify the strengths, limitations, and applications of these techniques and models, and to highlight new research directions in the field. Quantitative analysis of SOM can be performed using various parameters, including oxidation kinetics, lability, carbon management index, humification degree, humification index, and humification ratio. On the other hand, qualitative evaluation of SOM can involve techniques such as oxidizability, high-performance size-exclusion chromatography, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, visual examination, smell, assessment of microorganism content, plant growth, cation exchange capacity, type of organic material, and decomposition. These techniques and parameters provide valuable insights into the characteristics and transformation of SOM, enabling a comprehensive understanding of its dynamics. Evaluating SOM dynamics is of utmost importance as it is a determining factor for soil health, fertility, organic matter stability, and sustainability. Therefore, developing SOM models and other assessment techniques based on soil properties, environmental factors, and management practices can serve as a tool for sustainable management. Long-term or extensive short-term experimental data should be used for modeling to obtain reliable results, especially for quantitative SOM transformation analysis, and changes in the quality and quantity of SOM should be considered when developing sustainable soil management strategies.

Distinct Non-conservative Behavior of Dissolved Organic Matter after Mixing Solimões/Negro and Amazon/Tapajós River Waters.

Positive and negative electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry and 1H NMR revealed major compositional and structural changes of dissolved organic matter (DOM) after mixing two sets of river waters in Amazon confluences: the Solimões and Negro Rivers (S + N) and the Amazon and Tapajós Rivers (A + T). We also studied the effects of water mixing ratios and incubation time on the composition and structure of DOM molecules. NMR spectra demonstrated large-scale structural transformations in the case of S + N mixing, with gain of pure and functionalized aliphatic units and loss of all other structures after 1d incubation. A + T mixing resulted in comparatively minor structural alterations, with a major gain of small aliphatic biomolecular binding motifs. Remarkably, structural alterations from mixing to 1d incubation were in essence reversed from 1d to 5d incubation for both S + N and A + T mixing experiments. Heterotrophic bacterial production (HBP) in endmembers S, N, and S + N mixtures remained near 0.03 μgC L-1 h-1, whereas HBP in A, T, and A + T were about five times higher. High rates of dark carbon fixation took place at S + N mixing in particular. In-depth biogeochemical characterization revealed major distinctions between DOM biogeochemical changes and temporal evolution at these key confluence sites within the Amazon basin.

Optical properties and molecular composition of wintertime atmospheric water-soluble organic carbon in different coastal cities of eastern China

To evaluate the optical properties and molecular composition of water-soluble organic carbon (WSOC) in the atmosphere of coastal cities, particle samples were collected in Tianjin, Qingdao and Shanghai, three coastal cities in eastern China. Subsequent analysis by ultraviolet visible and fluorescence spectrometer and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry were performed. The results showed that the concentration levels and light absorption ability of WSOC decreased from the north to south cities, ranking as Tianjin > Qingdao > Shanghai. Three major fluorescent components including less‑oxygenated humic-like substances (52–60 %), highly‑oxygenated humic-like substances (15–31 %) and protein-like substances (17–31 %) were identified in WSOC based on the fluorescence spectroscopy and parallel factor analysis, which might be closely related to anthropogenic emissions and continental sources as well as secondary formation processes. Five subgroups of molecular components were further identified in WSOC, including the predominant CHON compounds (35–43 %), sulfur-containing compounds (i.e., CHONS and CHOS compounds, 24–43 %), CHO compounds (20–26 %) and halogen-containing compounds (1–7 %). Compared to marine air masses influenced samples, WSOC affected by continental air masses exhibited higher light absorption coefficients and generally had a higher degree of aromaticity and unsaturation, as well as contained more molecular formulas of WSOC, especially enriched with sulfur-containing compounds. In contrast, relatively more abundant halogen-containing compounds were identified in the marine air masses influenced samples. Overall, this study provided new insights into the light-absorbing and chemical properties of WSOC in coastal cities, especially under the influences of continental and marine air masses.

Molecular insights into the impacts of acid mine drainage on dissolved organic matter dynamics in pit lakes

Pit lakes are artificial hydrological features created by mining operations that typically suffer from acid mine drainage (AMD), which not only endangers water quality but also exacerbates carbon loss. However, the impacts of AMD on the fate and role of dissolved organic matter (DOM) in pit lakes remain unclear. This study employed negative electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) combined with biogeochemical analysis to examine DOM molecular variations and environmental controls across the AMD-induced acidic and metalliferous gradients in five pit lakes. The results demonstrated distinct DOM pools in pit lakes characterized by the prevalence of smaller aliphatic compounds compared to other waterbodies. AMD-induced geochemical gradients promoted DOM heterogeneity among pit lakes, with acidic pit lakes containing more lipid-like compounds. Acidity and metals enhanced DOM photodegradation, reducing the content, chemo-diversity and aromaticity. Organic sulfur was detected in high abundance, potentially from sulfate photo-esterification and mineral flotation agent. Furthermore, microbial involvements in carbon cycling were revealed by DOM-microbe correlation network, but microbial contributions to the DOM pools decreased under acidic and metal stresses. These findings highlight abnormal carbon dynamics caused by AMD pollution and integrate DOM fate into pit lake biogeochemistry, thereby contributing to management and remediation.

Robust High-Throughput Proteomics Identification and Deamidation Quantitation of Extinct Species up to Pleistocene with Ultrahigh-Resolution MALDI-FTICR Mass Spectrometry.

Peptide mass fingerprinting (PMF) using MALDI-TOF mass spectrometry allows the identification of bone species based on their type I collagen sequence. In the archaeological or paleontological field, PMF is known as zooarchaeology mass spectrometry (ZooMS) and is widely implemented to find markers for most species, including the extinct ones. In addition to the identification of bone species, ZooMS enables dating estimation by measuring the deamidation value of specific peptides. Herein, we report several enhancements to the classical ZooMS technique, which reduces to 10-fold the required bone sample amount (down to the milligram scale) and achieves robust deamidation value calculation in a high-throughput manner. These improvements rely on a 96-well plate samples preparation, a careful optimization of collagen extraction and digestion to avoid spurious post-translational modification production, and PMF at high resolution using matrix-assisted laser desorption ionization Fourier transform ion cyclotron resonance (MALDI-FTICR) analysis. This method was applied to the identification of a hundred bones of herbivores from the Middle Paleolithic site of Caours (Somme, France) well dated from the Eemian Last Interglacial climatic optimum. The method gave reliable species identification to bones already identified by their osteomorphology, as well as to more challenging samples consisting of small or burned bone fragments. Deamidation values of bones originating from the same geological layers have a low standard deviation. The method can be applied to archaeological bone remains and offers a robust capacity to identify traditionally unidentifiable bone fragments, thus increasing the number of identified specimens and providing invaluable information in specific contexts.

Presence of aromatic-rich organic matter and its characterization in grout materials: Implications for radionuclide immobilization

Grout materials are commonly used to immobilize low-level radioactive waste. Organic moieties can be unintentionally present in common ingredients used to make these grout waste forms, which may result in the formation of organo-radionuclide species. These species can positively or negatively affect the immobilization efficiency. However, the presence of organic carbon compounds is rarely considered in models or characterized chemically. Here, we quantify the organic pool of grout formulations with and without slag, as well as the individual dry ingredients used to make the grout samples (ordinary Portland cement (OPC), slag and fly ash), including total organic carbon (TOC) and black carbon, followed by aromaticity evaluation and molecular characterization via Electro Spray Ionization Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (ESI-FTICRMS). All dry grout ingredients contained significant amounts of organic carbon, ranging from 550 mg/kg to 6250 mg/kg for the TOC pool, with an averaged abundance of 2933 ± 2537 mg/kg, of which 60 ± 29% was composed of black carbon. The significant abundance of a black carbon pool implies the presence of the aromatic-like compounds, which was further identified by both phosphate buffer-assisted aromaticity evaluation (e.g., >1000 mg-C/kg as aromatic-like carbon in the OPC) and dichloromethane (DCM) extraction with ESI-FTICRMS analysis. Besides aromatic-like compounds, other organic moieties were also detected in the OPC, such as carboxyl-containing aliphatic molecules. While the organic compound only consists of minor fractions of the grout materials investigated, our observations of the presence of various radionuclide-binding organic moieties suggests the potential formation of organo-radionuclides, such as radioiodine, which might be present at lower molar concentrations than TOC. Evaluating the role of organic carbon complexation in controlling the disposed radionuclides, especially for those radionuclides with strong association with organic carbon, has important implications for the long-term immobilization of radioactive waste in grout systems.