Anionic Molecules Research Articles

Fluorinated functional groups enhanced composite in-situ gel electrolytes for high voltage cathode of quasi solid-state lithium battery

Gel electrolyte is an ideal system for improving the cycling stability and safety of lithium metal battery. However, traditional gel system with acrylic ester system is still not suitable for high-voltage battery system limited by its intrinsic structure and unstable interface. The polymer structures with -CF3 modified acrylic ester are proposed to improve the stability of both structure and interface in high-voltage battery systems. The LiF-rich anode-electrolyte interface assisted by fluorine contained in-situ gel electrolyte ensures stable cycling of lithium anode. The quasi-solid state lithium battery assembled with the LiFePO4 can still achieve a capacity retention rate of 81.2 % after 900 cycles at a rate of 1 C. Furthermore, the uniform organic cathode-electrolyte interface constructed by crosslinked -CF3 modified polymer effectively inhibits the corrosion of HF on the cathode material. The interaction between the anion and solvent molecules prevents the continuous decomposition reaction of the electrolyte on the surface of the LiCoO2 cathode at high voltage, which guarantees LiCoO2 battery can still achieve a capacity retention rate of 82.1 % after 500 cycles at a voltage of 4.45V. Design of fluorine contained in-situ polymer gel electrolyte could promote the development of quasi solid-state battery in practical industrial application.

Adsorption dynamics of heavy oil droplets on silica: Effect of asphaltene anionic carboxylic

Understanding the adsorption behavior of asphaltene molecules on the surfaces of oil reservoir solids is essential for optimizing oil recovery processes. This study employed molecular dynamics simulations to investigate the adsorption behavior of oil droplets composed of charged and neutral asphaltenes on silica surfaces. The results revealed that oil droplet containing anionic asphaltene molecules were more likely to adsorb onto silica surfaces and exhibited greater resistance to detachment compared to oil droplet containing neutral asphaltene molecules. Specifically, anionic asphaltene molecules tended to accumulate at the oil-water-silica interface, whereas neutral asphaltene molecules primarily adsorbed near the oil-water interface. These findings provide valuable insights into the differing adsorption dynamics of charged and neutral asphaltene molecules on silica surfaces.

Electrochemical characterization of carbon black in different redox probes and their application in electrochemical sensing

Carbon black - materials rich in carbon nanostructures - have been successfully applied as modifiers of electrochemical transducers, rivalling other carbon nanomaterials for cost and ease-of-use. Despite the remarkable promise of this nanomaterial, no study has yet comparatively characterised a wide range of different grades of carbon black for their utility in electrochemical sensors. Here, we explore several commonly-studied carbon black grades (N220, N234, N326, N330, N339, N375, N550, N660 and Lamp Black-101), alongside relatively newer grades (Printex®-200, Printex® G, Printex® XE-2B, and Printex® Zeta) for their application in electrochemical sensors. The effects of coating glassy carbon electrodes with carbon black on electrode performance were studied by cyclic voltammetry using three redox probes: ferri-/ferrocyanide (anionic probe molecules), ferrocenemethanol (neutral) and hexaammineruthenium (cationic). Raman Spectroscopy characterisation of the different grades associated a lower degree of graphitisation with superior electrode modifiers. Generally, modification increased the anodic peak current for ferri-/ferrocyanide probes; and lowered anodic potential for ferri-/ferrocyanide and hexaammineruthenium probes. Increases in peak current and potential observed at ferrocenemethanol are consistent with the increased tendency for this probe to adsorb to the surface of modified electrodes. N330 and Printex® XE-2B displayed the best electrocatalytic properties in terms of enhanced peak currents and lowered anodic overpotentials for the redox probes. CB grades were used to modify screen-printed carbon electrodes and the obtained sensors examined for anodic detection of reduced nicotinamide adenine dinucleotide (NADH) cofactor by cyclic voltammetry. Printex® XE-2B significantly improved the detection of NADH and was further used for chronoamperometric detection of NADH at low overpotentials. Grades N220, N375, N550 and P-G showed their suitability as enzyme scaffolds for sensor fabrication, as determined by their preservation of the activity of a NAD-dependent aldehyde dehydrogenase.

Versatile Cell Penetrating Peptide for Multimodal CRISPR Gene Editing in Primary Stem Cells.

CRISPR gene editing offers unprecedented genomic and transcriptomic control for precise regulation of cell function and phenotype. However, delivering the necessary CRISPR components to therapeutically relevant cell types without cytotoxicity or unexpected side effects remains challenging. Viral vectors risk genomic integration and immunogenicity while non-viral delivery systems are challenging to adapt to different CRISPR cargos, and many are highly cytotoxic. The arginine-alanine-leucine-alanine (RALA) cell penetrating peptide is an amphiphilic peptide that self-assembles into nanoparticles through electrostatic interactions with negatively charged molecules before delivering them across the cell membrane. This system has been used to deliver DNAs, RNAs, and small anionic molecules to primary cells with lower cytotoxicity compared to alternative non-viral approaches. Given the low cytotoxicity, versatility, and competitive transfection rates of RALA, we aimed to establish this peptide as a new CRISPR delivery system in a wide range of molecular formats across different editing modalities. We report that RALA was able to effectively encapsulate and deliver CRISPR in DNA, RNA, and ribonucleic protein (RNP) formats to primary mesenchymal stem cells (MSCs). Comparisons between RALA and commercially available reagents revealed superior cell viability leading to higher numbers of transfected cells and the maintenance of cell proliferative capacity. We then used the RALA peptide for the knock-in and knock-out of reporter genes into the MSC genome as well as for the transcriptional activation of therapeutically relevant genes. In summary, we establish RALA as a powerful tool for safer and effective delivery of CRISPR machinery in multiple cargo formats for a wide range of gene editing strategies.

Theoretical evidence for a pH-dependent effect of carbonate on the degradation of sulfonamide antibiotics

Carbonate (CO32−/HCO3−) have a significant impact on advanced oxidation processes (AOPs) by consuming reactive free radicals such as HO• to generate CO3•-. However, research on the mechanisms and kinetics of CO3•- remains limited. This study investigates the degradation mechanism and kinetics of sulfonamide antibiotics (SAs) by CO3•- through theoretical calculations. The calculation results revealed that the effect of CO3•- on SAs degradation is pH-dependent due to the dissociable sulfonamide group (-SO2NH-) of SAs in the common water treatment pH range (3–8). The main reaction type of CO3•- with both neutral and anionic molecules of SAs is single electron transfer reaction. Frontier molecular orbital theory (FMO) illustrated that deprotonation of the sulfonamide group of SAs decreases the charge density on the heterocyclic ring, facilitating the electrophilic addition of CO3•-. The second-order rate constants of the neutral and anionic molecules of SAs with CO3•- were calculated as 7.57 × 101∼1.84 × 108 and 1.81 × 107∼7.94 × 109 M−1 s−1, respectively, resulting in an increase in the apparent reaction rate constants with pH. Stepwise multiple linear regression was employed to predict reactivity with anionic sulfonamide antibiotics (SAs−). Two models with outstanding prediction and stability were developed with coefficients of determination R2 of 0.660 and 0.681, respectively. The degradation kinetics simulation indicated that in the UV/H2O2 process in the presence of carbonate, the degradation rate of SAs increased with pH. Furthermore, the contribution of CO3•- to SMX degradation increased while that of HO• decreased. This study highlights the contribution of carbonates to the micropollutant degradation in the UV/H2O2 process as the model, providing theoretical insights into the development of carbonate-based AOPs.

Emerging therapeutic strategies targeting extracellular histones for critical and inflammatory diseases: an updated narrative review.

Extracellular histones are crucial damage-associated molecular patterns involved in the development and progression of multiple critical and inflammatory diseases, such as sepsis, pancreatitis, trauma, acute liver failure, acute respiratory distress syndrome, vasculitis and arthritis. During the past decade, the physiopathologic mechanisms of histone-mediated hyperinflammation, endothelial dysfunction, coagulation activation, neuroimmune injury and organ dysfunction in diseases have been systematically elucidated. Emerging preclinical evidence further shows that anti-histone strategies with either their neutralizers (heparin, heparinoids, nature plasma proteins, small anion molecules and nanomedicines, etc.) or extracorporeal blood purification techniques can significantly alleviate histone-induced deleterious effects, and thus improve the outcomes of histone-related critical and inflammatory animal models. However, a systemic evaluation of the efficacy and safety of these histone-targeting therapeutic strategies is currently lacking. In this review, we first update our latest understanding of the underlying molecular mechanisms of histone-induced hyperinflammation, endothelial dysfunction, coagulopathy, and organ dysfunction. Then, we summarize the latest advances in histone-targeting therapy strategies with heparin, anti-histone antibodies, histone-binding proteins or molecules, and histone-affinity hemoadsorption in pre-clinical studies. Finally, challenges and future perspectives for improving the clinical translation of histone-targeting therapeutic strategies are also discussed to promote better management of patients with histone-related diseases.

Low-Molecular Weight Branched Polyethylenimine Reduces Cytokine Secretion from Human Immune System Monocytes Stimulated with Bacterial and Fungal PAMPs.

The innate immune system is an evolutionarily conserved pathogen recognition mechanism that serves as the first line of defense against tissue damage or pathogen invasion. Unlike the adaptive immunity that recruits T-cells and specific antibodies against antigens, innate immune cells express pathogen recognition receptors (PRRs) that can detect various pathogen-associated molecular patterns (PAMPs) released by invading pathogens. Microbial molecular patterns, such as lipopolysaccharide (LPS) from Gram-negative bacteria, trigger signaling cascades in the host that result in the production of pro-inflammatory cytokines. LPS stimulation produces a strong immune response and excessive LPS signaling leads to dysregulation of the immune response. However, dysregulated inflammatory response during wound healing often results in chronic non-healing wounds that are difficult to control. In this work, we present data demonstrating partial neutralization of anionic LPS molecules using cationic branched polyethylenimine (BPEI). The anionic sites on the LPS molecules from Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) are the lipid A moiety and BPEI binding create steric factors that hinder the binding of PRR signaling co-factors. This reduces the production of pro-inflammatory TNF-α cytokines. However, the anionic sites of Pseudomonas aeruginosa (P. aeruginosa) LPS are in the O-antigen region and subsequent BPEI binding slightly reduces TNF-α cytokine production. Fortunately, BPEI can reduce TNF-α cytokine expression in response to stimulation by intact P. aeruginosa bacterial cells and fungal zymosan PAMPs. Thus low-molecular weight (600 Da) BPEI may be able to counter dysregulated inflammation in chronic wounds and promote successful repair following tissue injury.

Study of chemical, kinetic, and theoretical sorption properties of activated carbons obtained from agroindustrial origin, comparison of anionic and cationic model molecules: Part II—ZnCl2 activation

Study of chemical, kinetic, and theoretical sorption properties of activated carbons obtained from agroindustrial origin, comparison of anionic and cationic model molecules: Part II—ZnCl2 activation

Compact Polyelectrolyte Complexes of Poly(l-Lysine) and Anionic Polysaccharides.

Compact polyelectrolyte complexes (CoPECs) can exhibit mechanical properties similar to those of biological tissues and other interesting properties, such as self-healing. To date, a variety of CoPECs prepared from synthetic polyelectrolytes have been investigated, but there are very few examples based entirely on biopolymers. We describe here an investigation of CoPECs based on poly(l-lysine) (PLL) with sodium hyaluronate (HA) and alginate (Alg). A 2:1 ratio of cation:anion and 0.25 M NaBr was beneficial for the formation of viscoelastic PLL-HA CoPECs, with the favorable ratio attributed to the spacing of carboxylates on HA being one every two saccharide units. In contrast, 1.0 M NaBr and a 1:1 ratio were better for PLL-Alg CoPECs. Both CoPECs swelled or retained a constant volume when immersed in hypertonic media, but contracted in hypotonic media. The loading of molecules into the PLL-HA (2:1) CoPECs was investigated. Higher loadings were achieved for anionic molecules compared to cations, presumably due to the excess cationic binding sites on the networks. The times required for full release of the molecules ranged from less than 2 h for neutral paracetamol to about 48 h for crystal violet and diclofenac.

Applicability of cationic surfactants, anionic surfactants, and nonionic surfactants as foaming agents for foamed concrete: surface activity, foamability, and interaction with cement

Selecting the appropriate surfactant as a foaming agent is crucial in the production of foamed concrete. In this study, multiple technological approaches were employed for the investigation of the effect of three different types of surfactants as foaming agents; the approaches included surface tension measurement, zeta potential analysis, spectrophotometry, and nanoindentation. The results showed that the surface activity, solution viscosity, and environmental pH all influenced the generation and stability of foam in foaming agents. The adsorption process of surfactants onto cement particles was complex and could be effectively explained using the double-layer theory. The adsorption of anionic surfactant molecules on cement particles significantly altered the zeta potential, up to −17 mV, with an adsorption efficiency over 10 times greater than that of cationic surfactants and more than 5 times greater than that of nonionic surfactants. Furthermore, after cement hardening, the mechanical properties of the resulting pores were notably improved due to the presence of adsorbed anionic surfactants, and the maximum compressive strength could exceed 10 MPa.

Synthesis, X-ray and antibacterial activity of new copper(II) thiosemicarbazone complexes derived from 4-formyl-3-hydroxy-2-naphthoic acid

New thiosemicarbazone ligand derived from 4-formyl-3-hydroxy-2-naphthoic acid (H3L·CH3OH (1)) and their two copper(II) complexes with composition [Cu(H2L)Cl]2.2(dmf) (2), [Cu(H2L)NO3(dmf)] (3) were synthesized and characterized by thermal analysis, IR-, EPR- spectroscopy and single X-ray diffraction method. In both complexes the mono-deprotonated ligand coordinate tridentate to Cu(II) ion by ONS donor atoms provided by phenolic oxygen, azomethine nitrogen and thiol sulfur. In 2 binuclear complex has the square–planar environment of one copper(II) completed by Cl- anion, while a tetragonal pyramid of other metal is formed by Cl- anion and S atom from the neighboring organic ligand. The copper ion in the mononuclear complex 3 adopt a square-pyramidal structure, where the coordination number of copper(II) ion is adjusted to 5 by O atoms of NO3− anion and dimethylformamide molecule. Magnetic investigations of complex 2 revealed the presence of noticeable magnetic couplings between Cu(II) ions, while compound 3 shows the behavior typical of magnetically isolated Cu(II) centers. The compounds tested against St. aureus, C. albicans, E. coli and Kl. Pneumonia were found to be more active against gram-positive bacteria strains.

Utilizing excited-state proton transfer fluorescence quenching mechanism, layered rare earth hydroxides enable ultra-sensitive detection of nitroaromatic

Convenient, rapid, and accurate detection of nitroaromatic organic toxins and harmful substances is of great significance in research. In the present study, two-dimensional layered rare-earth hydroxides (LYH) were used as ion-exchange matrix materials, and the anionic fluorescent dye molecules (HPTS) were successfully introduced into the LYH structures in situ via a simple and effective “plug-and-play” strategy, which gave the compounds ultra-sensitive fluorescence sensing detection of nitrobenzene, p-nitrotoluene and p-nitrophenol (Fluorescence response time < 1 sec, and the LOD for nitrobenzene, p-nitrophenol and p-nitrotoluene reached an impressive 349 ppb, 22 ppb and 98 ppb, respectively). Combined with theoretical calculations, we elucidated in detail the fluorescence quenching response mechanism of the LYH-HPTS towards nitroaromatic. Additionally, we also constructed fluorescent paper sensor, which effectively transformed the LYH-HPTS from theoretical detection to device application. The LYH-HPTS material is not only simple to synthesize, cost-effective and stable, but also has the features of fast response, excellent sensitivity and selectivity, and good reproducibility, which provides a new approach for the rapid and accurate detection of nitroaromatic.

[C(NH2)3]10(MoO3)10(PO4)2(HPO4)2·5H2O: Synergy effect of multiple functional units results in significant birefringence

In recent years, research has demonstrated the efficacy of synthesizing linear and nonlinear optical materials with exceptional properties through the synergy interaction of large anisotropic groups. Nevertheless, there is a paucity of studies focusing on the concurrent incorporation of planar π-conjugated groups and distorted d0 transiton metal octahedra into phosphates system. A novel organic–inorganic hybrid phosphate, namely, [C(NH2)3]10(MoO3)10(PO4)2(HPO4)2·5H2O (GMPO), which was synthesized using hydrothermal approach and presented in this study. GMPO exhibits a three-dimensional network structure composed of [(MoO3)5(PO4) (HPO4)]5− anionic group, water molecules, and guanidine cations interconnected through hydrogen bonding. GMPO possesses a notable birefringence of 0.158@550 nm with a band gap of 3.43 eV, suggesting its possible use as the UV birefringent material. Theoretical calculation suggests that the significant birefringence of GMPO is primarily attributed to the synergy effect of multifarious functional units contained in title compound.

Precise Regulation the Multiemission Based on Soft Double Salt for Information Encryption.

Manipulation of multiemissive luminophores is meaningful for exploring luminescent materials. Herein, we report a soft double salt assembly strategy that could result in well-organized nanostructures and different luminescence based on multiple weak intermolecular interactions thanks to the existence of electrostatic attraction between the anionic and cationic platinum(II) complexes. The cationic complexes B1 and B2 can coassemble with anionic complex A, respectively, and the emission switches from monomeric and excimeric emission to the triplet metal-metal-to-ligand charge transfer (3MMLCT) along with morphology changes from 0-dimensional (0-D) nanospheres to 3-dimensional (3-D) nanostructures. It is demonstrated that an isodesmic growth mechanism is adopted during the spontaneous self-assembly process, and the relative negative ΔG values make the anionic and cationic complex molecules prefer to form aggregates based on π-π stacking, Pt···Pt interactions, and electrostatic interactions. The coassembly strategy between anionic and cationic complexes endows them with multicolor luminescent and apparent color as optical materials for advanced information encryption.

Stable Lithium Metal Batteries Enabled by Lithiophilic Core-Shell Nanowires on Copper Foam.

Lithium (Li) metal batteries have attracted considerable research attention due to their exceptionally high theoretical capacity. However, the commercialization of Li metal batteries faces challenges, primarily attributed to uncontrolled growth of Li dendrites, which raises safety concerns and lowers coulombic efficiency. To mitigate Li dendrites growth and attain dense Li deposition, the hybrid SiO2-Cu2O lithiophilic film applied to a 3D copper foam current collector is developed to regulate the interfacial properties for achieving even and dense Li deposition. The SiO2-Cu2O possesses strong Li+ trapping capability through strong lithiophilicity from Cu2O. Additionally, the SiO2-Cu2O enables uniform ion diffusion through the domain-limiting effect of the holes in the SiO2 layer, inducing an even and dense Li plating/stripping behavior at a large capacity. Furthermore, the SiO2 layer promotes the formation of an initial high inorganic content Solid Electrolyte Interphase (SEI) through selective preferential binding with anion and solvent molecules. When the SiO2-Cu2O@Li anode is coupled with a LiFePO4 (LFP) cathode, the resulting full cell exhibits superior cycling stability and rate performance. These results provide a facile approach to construct a lithiophilic current collector for practical Li metal anodes.

Charge-Selective Photocatalytic Degradation of Organic Dyes Driven by Naturally Occurring Halloysite Nanotubes

This study explores the use of Halloysite NanoTubes (HNTs) as photocatalysts capable of decomposing organic dyes under exposure to visible or ultraviolet light. Through a systematic series of photocatalytic experiments, we unveil that the photodegradation of Rhodamine B, used as a model cationic dye, is significantly accelerated in the presence of HNTs. We observe that the extent of RhB photocatalytic degradation in 100 min in the presence of the HNTs is ~four times higher compared to that of bare RhB. Moreover, under optimized conditions, the as-extracted photodegradation rate of RhB (~0.0022 min−1) is comparable to that of the previously reported work on the photodegradation of RhB in the presence of tubular nanostructures. A parallel effect is observed for anionic Coumarin photodegradation, albeit less efficiently. Our analysis attributes this discrepancy to the distinct charge states of the two dyes, influencing their attachment sites on HNTs. Cationic Rhodamine B molecules preferentially attach to the outer surface of HNTs, while anionic Coumarin molecules tend to attach to the inner surface. By leveraging the unique properties of HNTs, a family of naturally occurring nanotube structures, this research offers valuable insights for optimizing photocatalytic systems in the pursuit of effective and eco-friendly solutions for environmental remediation.

One-pot synthesis, structural investigation, antitumor activity and molecular docking approach of two decavanadate compounds

Two bases-decavanadates coordination compounds [(C6H13N4)2][Mg(H2O)6]2[O28V10].6H2O (1) and [(C7H11N2)4][Mg(H2O)6][O28V10].4H2O (2) have been synthesized and well characterized using vibrational spectroscopy (infrared), UV–Visible analysis and single crystal X-ray diffraction technique. The formula unit, for both compounds, is composed by the decavanadate [V10O28]6−, hydrated magnesium ion, a counter anion and free water molecules. The transition metal adopts octahedral geometries in both compound (1) and (2). The existence of a multitude of hydrogen bonding interactions for both compounds provides a stable three-dimensional supramolecular structure. Optical absorption reveals a band gap energy indicating the semi-conductive nature of the compound. In this study, the cytotoxic and the anti-proliferative activities of compounds (1) and (2) on human cancer cells (U87 and MDA-MB-231) were investigated. Both compounds demonstrated dose-dependent anti-proliferative activity on U87 and MDA-MB-231 with respective IC50 values of 0.82 and 0.31 μM and 1.4 and 1.75 μM. These data provide evidence on the potential anticancer activity of [(C6H13N4)2][Mg(H2O)6]2[O28V10].6H2O and [(C7H11N2)4][Mg(H2O)2][O28V10].4H2O. Molecular docking of the compounds was also examined. Molecular docking studies were performed for both compounds against four target receptors and revealed better binding affinity with these targets in comparison to Cisplatin. Moreover, molecular docking investigations suggest that these compounds may function as potential inhibitors of proteins in brain and breast cells, exhibiting greater efficiency compared to Cisplatin.

GreenCut protein LPB1 is required for SQDG accumulation and optimal photosynthetic electron transfer from QA− to QB in Chlamydomonas reinhardtii

The thylakoid membrane lipid sulfoquinovosyldiacylglycerol (SQDG) is an anionic molecule that functions in stabilizing the thylakoid membranes and photosystem (PS) supercomplexes. In this study, we characterized the function of GreenCut protein CrLPB1, which encodes UDP-glucose pyrophosphorylase (UGP3), an enzyme involved in SQDG biosynthesis. The lpb1 mutants had reduced levels of SQDG, grew more slowly than wild type cells or the complemented strain under photoautotrophic conditions and were impacted in its rate of oxygen evolution and photosystem II (PSII) activity, especially electron transfer from QA− to QB. Furthermore, the structure of the PSII supercomplex and morphology of the thylakoid membranes were also both altered in lpb1. In conclusion, LPB1 is involved in SQDG biosynthesis, which in turn appears to be critical in maintaining normal thylakoid membrane structure and PSII activity/stability.

Nomenclature of the ancylite supergroup

Abstract The ancylite supergroup has been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association, with the general crystal chemical formula (M3+ x M2+2–x)(CO3)2[(OH) x ⋅(2–x)H2O] (1 ≤ x ≤ 2, Z = 2). The ancylite supergroup can be divided into two groups defined by different proportions of the M cation and hydroxyl anion and/or water molecule: the ancylite group is defined for 1 ≤ x ≤ 1.5; the kozoite group is defined for 1.5 &lt; x ≤ 2. The ancylite supergroup minerals are orthorhombic with space group Pmcn, or monoclinic with space group Pm11, and have a crystal structure with species-defining trivalent and divalent M cations (M = La3+, Ce3+, Nd3+, Ca2+, Sr2+ and Pb2+) which centre ten-vertex polyhedra formed by oxygen atoms at three independent O sites. Two vertices of the triangular (CO3)2– anion are oxygen atoms, whereas the third one, O(3), is statistically filled with (OH)– groups and H2O molecules. The triangular faces of three oxygen atoms of MO10 coordination polyhedra join the chains of this ten-vertex polyhedron, which is extended along the c axis. The (CO3) triangles connect chains in three dimensions. To date, eight valid mineral species with M2+ = Sr2+, Ca2+ and Pb2+ belong to the ancylite group [ancylite-(La), ancylite-(Ce), calcioancylite-(La), calcioancylite-(Ce), calcioancylite-(Nd), gysinite-(La), gysinite-(Ce) and gysinite-(Nd)]. Two hydroxyl carbonates with only rare earth elements as species-defining cations, kozoite-(La) and kozoite-(Nd) are members of the kozoite group.

Toward a More Comprehensive Approach for Dissolved Organic Matter Chemical Characterization Using an Orbitrap Fusion Tribrid Mass Spectrometer Coupled with Ion and Liquid Chromatography Techniques.

Dissolved organic matter (DOM) represents one of the largest active organic carbon pools in the global carbon cycle. Although extensively studied, only <10% of DOM has been chemically characterized into individual dissolved compounds due to its molecular complexity. This study introduced a more comprehensive DOM characterization method by coupling both ion chromatography (IC) and liquid chromatography (LC) with high mass accuracy and resolution mass spectrometry. We presented a new on-the-fly mass calibration of the Orbitrap technique by utilizing the "lock mass" function in the Orbitrap Fusion Tribrid mass spectrometer (OT-FTMS), which assures high mass accuracy at every scan by a postcolumn introduction of internal labeled standards. With both IC and LC, tested unlabeled standards of amino acids, small peptides, and organic acids were consistently below 1.0 ppm mass error, giving the OT-FTMS the potential of reaching mass accuracy of the Fourier-transform ion cyclotron resonance mass spectrometer. In addition to mass accuracy, a pooled quality control sample (QC) was used to increase reproducibility by applying systematic error removal using random forest (SERRF). Using an untargeted mass spectrometry approach, estuarine DOM samples were analyzed by OT-FTMS coupled to IC in negative mode and LC in positive mode detection to cover a wide range of highly cationic to highly anionic molecules. As a proof of concept, we focused on elucidating the structures of three distinct DOM compound classes with varied acidities and basicities. In UPLC-OT-FTMS, a total of 915 compounds were detected. We putatively elucidated 44 small peptides and 33 deaminated peptides of these compounds. With IC-OT-FTMS, a total of 1432 compounds were detected. We putatively elucidated 20 peptides, 268 deaminated peptides, and 188 organic acids. Except for five compounds, all putatively elucidated compounds were uniquely detected in their corresponding chromatography technique. These results highlight the need for combining these two techniques to provide a more comprehensive method for DOM characterization. Application of the combined IC and LC techniques is not limited to DOM chemical characterization. It can analyze other complex compound mixtures, such as metabolites, and anthropogenic pollutants, such as pesticides and endocrine-disrupting chemicals, in environmental and biological samples.