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Well-defined 3d–4f heterometallic supramolecular architectures have attracted attention because of their applications in the field of luminescence and magnetism. However, covalent metallo-supramolecular discrete complexes, decorated with hetero-metallic vertices, have never been reported because of the difficulties in design and control. Herein, we report a series of covalent metallo-supramolecular discrete complexes with 3d–4f vertices synthesized by hierarchical subcomponent self-assembly of tris(2-aminoethyl)amine, 2,6-diformyl-p-cresol, and lanthanide ions (Ln) with different amines and transition metal ions. The programmable self-assembly process results in the formation of triple-stranded hetero-metallic covalent organic discrete complexes, namely 3a–3c-(Ln, Zn) (Ln = SmIII, EuIII, DyIII, YbIII and LuIII) and 3a′-(Dy, Co), which are characterized by nuclear magnetic resonance (NMR) analysis, electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), and single-crystal X-ray analysis. Photophysical investigations disclose that the organic skeleton of 3a-(Ln, Zn) exhibits an excellent sensitizing ability toward SmIII, EuIII, and YbIII ions, displaying characteristic luminescence emission in both the visible and near-infrared (NIR) regions. AC susceptibility measurements of 3a′-(Dy, Co) reveal the frequency-independent performance under zero dc field, suggesting the absence of slow relaxation of magnetization. This work offers a new approach for the fabrication of discrete metallic covalent architectures with 3d–4f vertices. [ABSTRACT FROM AUTHOR]

A series of coordination compounds [CoIII2{(CoIICl(H4L)(H2O)3}3{(CoII(CH3COO)(H4L)(H2O)2}3]6+(Cl−)6·H2O (1), [Ni(H4L)2] (2), [Cu(H4L)2] (3) and [(H6L)CuCl3]·H2O (4) were synthesized by the reaction of (E)-1-(amino(1H-pyrazol-1-yl)methylene)guanidinium chloride (H5L·HCl) with Co(CH3COO)2·4H2O, Ni(CH3COO)2·4H2O (in the presence of triethylamine), Cu(CH3COO)2·H2O (in the presence of triethylamine) and CuCl2·2H2O in methanol, respectively. 1–4 were fully characterized by infrared spectroscopy, electrospray ionization mass spectrometry, single-crystal X-ray diffraction and elemental analyses. H5L·HCl is potentially a multidentate N-donor ligand, and coordinates to cobalt as a N4 donor in 1, and to nickel or copper as a N2 donor in 2–4. In the structure of 1, the coordination geometry around the CoIII or CoII atoms is distorted octahedral. In 2 and 3, the Ni and Cu atoms have a distorted square planar coordination geometry, whereas Cu in 4 exhibits a square-based pyramidal coordination geometry. In the packing diagrams of 1–4, the N atom 1H-pyrazole moiety and H–N of the 1,3,5-triazopentadienyl ligands act as a H-bond acceptor and donor towards neighbouring molecules, leading to 3D supramolecular networks. All complexes were tested as catalysts for the peroxidative oxidation of styrene to benzaldehyde. The effects of the oxidant type, styrene to catalyst molar ratio, and reaction temperature and time on the catalytic activity were investigated. Under optimized conditions in the presence of 4, high yields (up to 80%) of benzaldehyde can be achieved. [ABSTRACT FROM AUTHOR]

The reaction of 2-(2-(dicyanomethylene)hydrazineyl)benzoic acid (H2L1) with copper(II) acetate in the absence or presence of imidazole (im), 4,4′-bipyridine (4,4′-bipy) or pyridine (py) leads to the new complexes [Cu2(CH3OH)2(μ-L1a)2] (1), [Cu(L1a)(im)] (2), [Cu(L1a)(H2O)(4,4′-bipy)]·H2O (3) or [Cu(L1a)(py)]n (4), respectively, where (L1a)2− = (Z)-1-(2-carboxylatophenyl)-2-(1-cyano-2-imino-2-methoxyethylidene)hydrazin-1-ide. A one-pot activation of nitrile groups in the reaction of copper(II) acetate monohydrate with 2-(2-(dicyanomethylene)hydrazineyl)terephthalic acid (H3L2) in the presence of pyridine in methanol affords the trinuclear Cu(II) complex [Cu(py)2{Cu(py)(μ-L2a)}2] (5), where (L2a)3− = (Z)-2-((1-cyano-2-imino-2-methoxyethylidene)-1-(2,5-dicarboxylatophenyl)hydrazin-1-ide). Both arylhydrazone ligands and the auxiliary ligands were used to modulate the nuclearity and design of the supramolecular arrangements of the obtained Cu(II) complexes. The complexes were characterized by elemental analyses, electrospray ionization mass spectrometry (ESI-MS), and FT-IR spectroscopy. Their molecular structures were established using single crystal X-ray diffraction (SCXRD) analysis. The catalytic activity of the complexes was investigated for the microwave assisted 1,3-dipolar azide–alkyne cycloaddition reaction using a mixture of water and glycerol as reaction medium. Pre-catalyst 1 was found to be the most efficient one by affording a quantitative conversion to 1,4-disubstituted-1,2,3-triazoles after 30 minutes at 125 °C. The catalytic system proceeds with a broad scope of substrates according to "Click" rules. [ABSTRACT FROM AUTHOR]

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The concentration of target analyte in a mixture can be quantified by combining coulometric measurements with spray ionization mass spectrometry. A three‐electrode system screen printed on the polymer support acts both as the coulometry platform for electrochemical oxidation and the sample loading tip for spray ionization. After loading a droplet of the analyte solution onto the tip, two steps were taken to implement quantitation. First, the electrochemical oxidation potential was optimized with cyclic voltammetry followed by coulometric measurements to calculate the amount of oxidized analyte under a constant low voltage within a fixed period of time (5 s). Then, a high voltage (+4.5 kV) was applied to the tip to trigger spray ionization for measuring the oxidation yield from the native analyte ion and its oxidized product ion intensities by mass spectrometry. The analyte's native concentration is quantified by dividing the oxidized product's concentration (based on Coulomb's law) and the oxidation yield (estimated from mass spectrometry [MS] assuming that the parent and oxidation product have nearly the same ionization efficiencies). The workflow has an advantage in being free of any standard for constructing the quantitation curve. Several model compounds (tyrosine, dopamine, and angiotensin II) were selected for method validation. It was demonstrated that this strategy was feasible with an accuracy of ~15% for a wide coverage of different species including endogenous metabolites and peptides. As an example of its possible practical use, it was initially employed to make a bilirubin assay in urine. [ABSTRACT FROM AUTHOR]

Ultra high-resolution mass spectrometry (FT-ICR MS) coupled to electrospray ionization (ESI) provides unprecedented molecular characterization of complex matrices such as petroleum products. However, ESI faces major ionization competition phenomena that prevent the absolute quantification of the compounds of interest. On the other hand, comprehensive two-dimensional gas chromatography (GC × GC) coupled to specific detectors (HRMS or NCD) is able to quantify the main families identified in these complex matrices. In this paper, this innovative dual approach has been used to evaluate the ionization response of nitrogen compounds in gas oils as a case study. To this extent, a large gas oil dataset has been analyzed by GC × GC/HRMS, GC × GC-NCD and ESI(+/−)-FT-ICR MS. Then, the concentrations obtained from GC × GC-NCD have been compared to those obtained from FT-ICR MS hence proving that strong ionization competitions are taking place and also depending on the origin of the sample. Finally, multilinear regressions (MLR) have been used to quantitatively predict nitrogen families from FT-ICR MS measurements as well as start rationalizing the ionization competition phenomena taking place between them in different types of gas oils. [ABSTRACT FROM AUTHOR]

In this paper, an additive manufacturing process has been used to deposit nanoparticles on a substrate. In this innovative technique called the nano-electrospray laser deposition process, droplets of various nanosuspensions are dispensed onto a silicon substrate where subwavelength structures and bouncing droplets have been observed. An analytical model is presented for determining the temperature distribution in the substrate by considering the microdroplet as a ball lens. This lens continuously changes the focus of the laser beam as the droplet travels toward the substrate. The laser is either defocused or focused on the substrate forming locally decreased or enhanced heating near the center of the laser beam depending on the distance of the droplet from the substrate. It is found that the enhancement in heating differs for the nanosuspensions since their optical properties are different. The subwavelength structures determined from the post-pulse temperature qualitatively match with the experimental results. The steady end-period temperature is also compared with the experimentally observed temperature for bouncing droplets and the temperatures are in good agreement. [ABSTRACT FROM AUTHOR]

In the past, chrome yellow (lead chromate, PbCrO4), a bright orange-red substance, has been widely used as an inorganic pigment in the production of paints, coatings, and plastics. Herein, we demonstrate that laser desorption/ionization mass spectrometry (LDI-MS) is a powerful tool for the detection of lead chromate in solid residues. In fact, lead chromate in trace amounts is easily detectable by LDI-MS even from residues left as latent prints. For example, a latent print obtained by stamping the exposed laterally cut surface of a pencil over 50 years old on an acetonitrile-moistened paper, was successfully imaged for both lead and chromate using a Synapt G2 HDMS mass spectrometer. After rastering the print with a 355nm laser beam and recording positive- and negative-ion mass spectra over the range m/z 50-1200, we generated false-color 'heat maps' (single-ion images) for 208Pb+· (m/z 207.98) and Cr2O6 -· (m/z 199.85). The heat maps matched closely with the faint visual image of the pencil imprint. Moreover, our results confirmed that lead chromate was used in the pigment coatings of old pencils. Evidently, LDI-MS imaging is an efficient procedure to survey for the presence of lead and chromate in minerals and other materials. [ABSTRACT FROM AUTHOR]

In this paper, the effect of isotope-labeled analogs on the liquid chromatography-isotope dilution mass spectrometry (LC-IDMS) measurement was evaluated based on the comparison research of electrospray ionization responses (ESI) and matrix effect of melamine, C-melamine, C+N-melamine, and N-melamine. The isotope-labeled melamines had similar ionization efficiency with melamine in the electrospray ionization source, but the intensity of corresponding quantitative fragment ions had distinctive differences. Based on the density functional theory at the B3LYP/6-311+G** level, this phenomenon was explained very well. The rare cleavage pathways of melamine, which just could be exactly identified by N-labeled melamines, resulted in the difference of quantitative fragment ions between N-labeled melamines and melamine. The interaction of ESI response between melamine and isotope-labeled melamines was investigated using MRM monitor mode. N-labeled melamine had significant ion inter-suppression effect on melamine, while C-labeled melamine had little influence on melamine. Finally, the influence of different isotope-labeled melamines on the LC-IDMS result was evaluated using the IDMS correction factor ( θ). Taking the determination of melamine in milk powder as an example, the matrix effects of different isotope-labeled melamines and melamine had notable difference and the impact of this difference on the measurement results depended on the concentrations of analyte and matrix solution. It was worth noting that N-melamine exhibited significant ion suppression to melamine in matrix solution. The deviation of the results from IDMS method might reach 59% using N-melamine as internal standard in special matrix solution. [ABSTRACT FROM AUTHOR]

A terpyridine-based supramolecular cage was successfully synthesized by the self-assembly of a hexapodal metal–organic ligand with Zn2+. This metallo-cage exhibited two large parallel planes on the top and bottom with diameters close to 6 nm and a face-to-face distance close to 3.5 nm, thus possessing a large cavity. Electrospray ionization mass spectrometry (ESI-MS), nuclear magnetic resonance (NMR), two-dimensional nuclear Overhauser (2D-NOESY), and diffusion-ordered (DOSY) spectroscopies as well as transmission electron microscopy (TEM) and atomic force microscopy (AFM) measurements, unambiguously supported the formation of a supramolecular cage. Furthermore, the corresponding metal–organic gel was felicitously prepared in CH3CN/H2O and displayed good adsorption performance for dye molecules. [ABSTRACT FROM AUTHOR]

Direct mass spectrometry (MS) analysis is vital to chemical and biological investigations. However, measuring complex samples is challenging due to matrix interference, resulting in compromised MS performance. In this study, an integrated experimental protocol has been developed, combining in-capillary aptamer-functionalized solid-phase microextraction (SPME), extraction nanoelectrospray ionization (nanoESI), and miniature MS analysis. The established method was applied to analyze caffeine in electronic cigarette liquid and beverage samples as proof-of-concept demonstrations. A custom SPME strip fabricated with caffeine-binding aptamers was prepared with an immobilization density of up to 0.812 nmol cm−2. Critical parameters affecting the effects of extraction, desorption, and ionization were optimized. A novel transition ion ratio-based strategy with enhanced quantitation accuracy was developed. The analytical performance of the proposed method was evaluated under optimized conditions. Acceptable recoveries of 87.5–111.5% with relative standard deviations of 3.1–6.1% and satisfactory sensitivity with limits of detection of 1.5 and 3 ng mL−1 and limits of quantitation of 5 and 10 ng mL−1 were obtained, respectively. The developed approach demonstrates a promising potential for rapid on-site applications with appealing analytical performance and efficiency. [ABSTRACT FROM AUTHOR]

Nucleosides have been found to suffer in-source fragmentation (ISF) in electrospray ionization mass spectrometry, which leads to reduced sensitivity and ambiguous identification. In this work, a combination of theoretical calculations and nuclear magnetic resonance analysis revealed the key role of protonation at N3 near the glycosidic bond during ISF. Therefore, an ultrasensitive liquid chromatography-tandem mass spectrometry system for 5-formylcytosine detection was developed with 300 fold signal enhancement. Also, we established a MS1-only platform for nucleoside profiling and successfully identified sixteen nucleosides in the total RNA of MCF-7 cells. Taking ISF into account, we can realize analysis with higher sensitivity and less ambiguity, not only for nucleosides, but for other molecules with similar protonation and fragmentation behaviors. [ABSTRACT FROM AUTHOR]

Aconitum L. poisoning is a major type of poisoning caused by herbal medicines in many countries. However, despite its toxicity, Aconitum L. is still used because of its therapeutic value. Fuzi, the lateral root of Aconitum L., is one of the most important pharmacological parts. It is necessary for rational medication to figure out the types and contents of toxic Aconitum alkaloids (AAs) in Fuzi and its processed products. The present study aims to investigate the spatial distribution of toxic AAs in Fuzi and the quantification of AAs in various processing products through mass spectrometry methods. In this study, desorption electrospray ionization mass spectrometry imaging (DESI-MSI) was used to directly image the sections of raw Fuzi. The results showed a high content of diester alkaloids (DAs) and a relatively uniform distribution in the sections, while the content of monoester alkaloids (MAs) was low and uneven in the sections, distributed in the cortex, epidermis, vascular column, and other parts of the tissues. The content of non-ester alkaloids (NAs) was relatively minimum, and most of the NAs were distributed in the vascular column and the tightly connected cortex of the tissue. To further investigate the difference between raw and processed Fuzi, 60 known compounds were identified using UHPLC-QTOF-MS. The total contents of alkaloids in 7 processed Fuzi were lower than that in Shengfupian (SFP). Paofupian (PFP), Paotianxiong (PTX), Paofupian (PFP*), Danfupian (DFP), and Shufupian (SFP*) were the least similar. Zhengfupian (ZFP) and Chaofupian (CFP) had significantly reduced toxicity and increased efficacy compared with other processed products because the contents of active alkaloids in other processed products were also reduced. Understanding the distribution of metabolites and the composition changes after processing can guide users and herbal manufacturers to carefully choose the relatively safe and better therapeutic species of Fuzi. The information gathered from this study can contribute towards the improved and effective management of therapeutically important, nonetheless toxic, drugs such as Aconitum L. [ABSTRACT FROM AUTHOR]

High-temperature steam is required to produce hydrogen with Solid Oxide Electrolysis Cells (SOEC), but generating steam can be power-consuming. Concentrated solar power is a good candidate for replacing electricity or fossil fuel in generating steam. This paper investigated the effect of spray on radiation transfer in a novel solar steam generator designed to utilize spray cooling to enhance heat transfer. The Monte Carlo ray-tracing technique, considering the absorption of droplets, absorption of water vapor, and multiple scattering of droplets, is employed to analyze the flux density at the focal plane and the spatial scattering power distribution of droplets. The results show that the total incident power transmittance is found to be in positive proportion to the mean droplet diameter while in reverse proportion to the spray volume fraction. Since the maximum difference in spectral transmittances is less than 1%, it is not feasible to adjust the wavelength for higher transmittance. The nozzle position seems highly affects the solar power distribution, and the central area is more affected than the outer area. Thus, increasing the spray volume fraction may uniform the flux density but reduce the transmittance. The spatial scattering power analysis indicates that increasing the droplet diameter can effectively improve the transmittance when the spray volume fraction keeps constant, which may be a solution when applied to a large-scale steam generator. [ABSTRACT FROM AUTHOR]

Mass spectrometry imaging (MSI) is an effective technique for visualizing the distribution of lipids in tissues. The direct extraction-ionization methods using minute volumes of solvent for local components have the advantage of rapid measurement without any sample pretreatment. For effective MSI of tissues, it is necessary to understand the effect of solvent physicochemical properties on ion images. In this study, we report solvent effects on the lipid imaging of mouse brain tissue by tapping-mode scanning probe electrospray ionization (t-SPESI) which is capable of extraction-ionization using sub-pL solvents. To precisely measure lipid ions, we developed a measurement system incorporating a quadrupole-time-of-flight mass spectrometer. The differences in signal intensity and spatial resolution of lipid ion images were investigated using N,N-dimethylformamide (non-protic polar solvent), methanol (protic polar solvent) and their mixture. The mixed solvent was suitable for the protonation of lipids, and it provided high spatial resolution MSI. Results indicate that the mixed solvent improves the extractant transfer efficiency and minimizes charged droplets from an electrospray. The solvent selectivity study revealed the importance of solvent selection based on physicochemical properties for the advancement of MSI by t-SPESI. [ABSTRACT FROM AUTHOR]

A new nitrobenzoxadiazole (NBD)‐based chemosensor N′‐(7‐nitrobenzo[c][1,2,5]oxadiazol‐4‐yl)thiophene‐2‐carbohydrazide (NTCH) was synthesized for detecting Hg2+. NTCH could sense Hg2+ through a color change method from pale yellow to pink. Binding ratio of NTCH and Hg2+ was determined to be 1:1 with the analysis of electrospray ionization mass spectrometry and Job plot. Detection limit turned out to be 0.69 μM. In addition, NTCH could be successfully utilized for detecting Hg2+ in real water samples and visible color test strips. The probing mechanism of NTCH to Hg2+ was explained with 1H nuclear magnetic resonance (NMR) titration, Job plot, electrospray ionization mass spectrometry (ESI‐MS), and theoretical calculations. [ABSTRACT FROM AUTHOR]

Deep understanding of the polymerization and transformation of tungstate species in aqueous solution is of great significance for hydrometallurgical and chemical separation processes, such as solvent extraction, membrane separation and crystallization. In order to study the polymerization and transformation of tungstate species, the semi-quantitative characterization method of electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) was developed. In this paper, the tungsten speciation in simulative leaching solution was investigated in detail between pH 2.5 and 7 under various conditions (e.g. acid species, initial concentration, pH), and the results indicated that HCl was more conducive than HNO3 for the polymerization of tungsten at the same pH, and HAc accelerated the polymerization of tungsten species, especially in acid solution at lower pH; the morphological changes of each tungsten species tended to be consistent with the increase of tungsten concentration; pH strongly influenced the distribution of tungsten species. Then, the polymerization and transformation laws of tungstate species are summarized. W1 (monomers) are dominant species in weak acid and neutral solution, and aggregate into oligomeric species (e.g. W2, W4, W6). Transformations also exist among W2, W4 and W6. The polymerization process from W4 and W6 species to higher poly-tungstate (W10–12) was observed with the consumption of H+. This work aims to understand the polymerization and transformation of tungsten speciation using ESI-TOF-MS, which should provide useful information for the understanding and optimizing of industrial production and environmental processes, building a bridge between micro tungsten speciation and macro industrial applications. [ABSTRACT FROM AUTHOR]

Direct analysis of whole blood on bloodstained textiles is achieved with thread spray mass spectrometry (MS). This capability satisfies investigators' first priority in crime scene investigations, which is determining if a stain is blood. This thread spray method explores the use of evidentiary fabric threads for rapid determination of hemoglobin directly from whole blood within textiles without prior extraction steps. The multiplicity of information that can be derived from the thread spray MS method distinguishes it from the current presumptive Bluestar® method, by enabling the detection of hemoglobin (both α- and β-chains), the heme co-factor and lipids all from a single blood sample. Lipid composition was found to differ for blood samples originating from human, canine, and horse species. The robustness of the thread spray MS method as a forensic analytical platform was evaluated in three ways: (1) its successful applicability to samples previously tested by the Bluestar® presumptive method, offering a confirmatory test without prior sample pre-treatment, (2) successful detection of heme from previously washed fabrics, which demonstrated the unprecedented sensitivity of the thread spray method, and (3) the ability to analyze samples stored under ambient conditions for up to 30 days. These results attest to the potential capabilities of the thread spray MS platform in forensic serology, and its application for direct analysis of evidentiary garments, which confer the advantages of rapid analysis and the reduction of the false positive and negative identification rates for blood on textiles. [ABSTRACT FROM AUTHOR]

Ophiopogon japonicus (Thunb.) Ker-Gawl (Liliaceae), which is named as "Maidong" in China, is widely used in traditional Chinese medicine for treating fever, cough, inflammation, epistaxis, constipation, respiratory disease and gastrointestinal disorders. However, the systematic analysis of chemical constituents of O. japonicus has not been well established because of the complexity and trace. In this paper, an effective and reliable high-performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry method was successfully developed to separate and identify the chemical constituents from O. japonicus. As a result, a total of 30 compounds including steroidal saponins, homoisoflavonoids, allylbenzene, cholest and cryptomeridiol were screened or tentatively identified. Of them, three new steroidal saponins were found and tentatively characterized in O. japonicus. This study provides a meaningful material basis for further quality control and pharmacological research. [ABSTRACT FROM AUTHOR]

Sideritis , also named "ironwort," "mountain tea," or "shepherd's tea," is a genus of flowering plants used as herbal medicine in traditional Mediterranean-area medicine systems, and these plants are generally consumed as a herbal tea. Its use as herbal tea and in traditional herbal medicine is quite popular. There are currently few studies on Sideritis perfoliata L., and only one reports the use of a liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry (LC-DAD-ESI-MSn) profile and the content of phenolic compounds without considering a possible correlation with its biological activities. This paper aims to investigate the antioxidant activities by means of several different biological/biochemical assays (radical scavenging, reducing power, ferrous ion chelating, and total antioxidant by phosphomolybdenum and β-carotene bleaching methods) as well as analyze the enzyme inhibitory activities (against AChE (acetylcholinesterase), BChE (butyrylcholinesterase), tyrosinase, α-glucosidase, and α-amylase) as well as the total phenolics, flavonoids, and condensed tannins. The reported results on Sideritis perfoliata highlighted that methanol and water extracts generally showed higher radical scavenging and reducing power activities. A similar trend could be observed for phosphomolybdenum and ferrous ion chelating activities. Methanol extracts showed lower activity only for the β-carotene bleaching assay. [ABSTRACT FROM AUTHOR]

Ruthenium is a platinoid that exhibits a range of unique chemical properties in solution, which are exploited in a variety of applications, including luminescent probes, anticancer therapies, and artificial photosynthesis. This paper focuses on a recently demonstrated ability of this metal in its +3 oxidation state to form highly stable complexes with tris (hydroxymethyl)aminomethane (H2NC(CH2OH)3, Tris‐base or T) and imidazole (Im) ligands, where a single RuIII cation is coordinated by two molecules of each T and Im. High‐resolution electrospray ionization mass spectrometry (ESI MS) is used to characterize RuIII complexes formed by placing a RuII complex [(NH3)5RuIICl]Cl in a Tris buffer under aerobic conditions. The most abundant ionic species in ESI MS represent mononuclear complexes containing an oxidized form of the metal, ie, [XnRuIIIT2 – 2H]+, where X could be an additional T (n = 1) or NH3 (n = 0‐2). Di‐ and tri‐metal complexes also give rise to a series of abundant ions, with the highest mass ion representing a metal complex with an empirical formula Ru3C24O21N6H66 (interpreted as cyclo(T2RuO)3, a cyclic oxo‐bridged structure, where the coordination sphere of each metal is completed by two T ligands). The empirical formulae of the binuclear species are consistent with the structures representing acyclic fragments of cyclo(T2RuO)3 with addition of various combinations of ammonia and dioxygen as ligands. Addition of histidine in large molar excess to this solution results in complete disassembly of poly‐nuclear complexes and gives rise to a variety of ionic species in the ESI mass spectrum with a general formula [RuIIIHiskTm (NH3)n − 2H]+, where k = 0 to 2, m = 0 to 3, and n = 0 to 4. Ammonia adducts are present for all observed combinations of k and m, except k = m = 2, suggesting that [His2RuIIIT2 − 2H]+ represents a complex with a fully completed coordination sphere. The observed cornucopia of RuIII complexes formed in the presence of histidine is in stark contrast to the previously reported selective reactivity of imidazole, which interacts with the metal by preserving the RuT2 core and giving rise to a single abundant ruthenium complex (represented by [Im2RuIIIT2 − 2H]+ in ESI mass spectra). Surprisingly, the behavior of a hexa‐histidine peptide (HHHHHH) is similar to that of a single imidazole, rather than a single histidine amino acid: The RuT2 core is preserved, with the following ionic species observed in ESI mass spectra: [HHHHHH·(RuIIIT2)m − (3m‐1)H]+ (m = 1‐3). The remarkable selectivity of the imidazole interaction with the RuIIIT2 core is rationalized using energetic considerations at the quantum mechanical level of theory. [ABSTRACT FROM AUTHOR]

We present a surface sampling method for the chemical analysis of liquid-immersed solid samples. Liquid immersion allows samples to be kept in a hydrated state. We employed cavitation generated by high-intensity focused ultrasound for localized material removal. The appropriate transducer–sample distance was determined using the actuating ultrasound transducer prior to sampling, allowing sonication in focus despite surface height variation. We demonstrate the proposed surface sampling method on water-submerged glass cover slides painted with permanent markers, achieving sampling with tunable spot size down to 500 μ m. The removed and collected material was transferred for chemical analysis by electrospray ionization mass spectrometry, which showed mass peaks characteristic to the permanent markers. [ABSTRACT FROM AUTHOR]

Here, we report the synthesis and atomic structure of a Ag15Cu12(SR)18(CH3COO)3·(C6H14) nanocluster (Ag15Cu12 for short, SR denotes cyclohexanethiol), confirmed by single-crystal X-ray diffraction (SC-XRD), electrospray ionization mass spectrometry (ESI-MS), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). X-ray crystallographic analysis revealed that Ag15Cu12 consisted of an irregular Ag12 core, stabilized by the Ag3Cu12(SR)18(CH3COO)3 shell. The shell consisted of two nearly planar Cu3(SR)6 moieties, three monomeric [–SR–Ag–SR–] units and three Cu2(CH3COO) staples. Furthermore, time-dependent density functional theory (TD-DFT) simulation was performed to interpret the optical absorption features of Ag15Cu12. Overall, this work will broaden and deepen the understanding of Ag–Cu alloy nanoclusters. [ABSTRACT FROM AUTHOR]

The assembly studies of high-nuclear clusters have received much interest in recent years due to their targeted synthesis for some special usages. A Schiff base ligand 2-[N-(2-hydroxynaphthylidene)amino]-2-(hydroxymethyl)propane-1,3-diol (H4L) was thus prepared in this work and was allowed to react with [Cu2(OAc)4(H2O)2] and Dy(NO)3·6H2O, giving a high-nuclear 3d–4f heterometallic Cu12Dy14 nanocluster (1) with the formula [(C2H5)3NH]4[Cu12Dy14O(OH)16(H2L)8(HL)4(HL′)4(OAc)10](NO3)4(OAc)2·6CH3CN·5EtOH·1.5H2O (H3L′ = 1,1,1-tris-(hydroxymethyl)methanamine). It features a centipede-shaped structure constructed from eight Dy3Cu cubanes sharing the Dy(III) vertices. Its assembly mechanism was explored through time-dependent high-resolution electrospray ionization mass spectrometry (HRESI-MS). This revealed that the hierarchical assembly of 1 undergoes two possible routes: H4L → DyCuL → Dy2CuL → Dy3Cu2L2 → Dy4Cu2L2 → Dy4Cu3L3 → Dy5Cu4L4→ Dy14Cu12L12L′4 and H4L → DyCuL → DyCu2L → Dy2Cu2L2 → Dy2Cu3L4 → Dy3Cu4L4 → Dy5Cu4L4 → Dy14Cu12L12L′4. These results not only provide solid evidence for understanding the assembly mechanism of high-nuclear 3d–4f clusters, but also help to give some hints for designing and preparing new high-nuclear clusters. [ABSTRACT FROM AUTHOR]

A new [PdPtL4]4+ heterobimetallic cage containing hydrazone linkages has been synthesised using the sub-component self-assembly approach. 1H and DOSY nuclear magnetic resonance (NMR) spectroscopy and electrospray ionisation mass spectrometry (ESIMS) data were consistent with the formation of the [PdPtL4]4+ architecture. The cage was stimulus-responsive and could be partially disassembled and reassembled by the addition of dimethylaminopyridine (DMAP) and p-tolenesulfonic acid (TsOH), respectively. Additionally, the stability of the hydrazone cage against hydrolysis in the presence of water and nucleophilic decomposition in the presence of guest molecules was compared to a previously synthesised imine-containing [PdPtL4]4+ cage. It was established that the hydrazone linkage was more resistant to hydrolysis. Furthermore, the host–guest (HG) chemistry with a series of drug and drug-like molecules was examined. The hydrazone cage was shown to interact with cisplatin while the smaller imine cage was shown to interact with 5-fluorouracil and oxaliplatin in CD3CN. No HG interactions were observed in the more polar d6-DMSO. In vitro antiproliferative activity studies demonstrated both cages were active against the cancer cell lines tested and displayed half-maximal inhibitory (IC50) values in the range of 25–35 μM. Most [PdPtL4]4+-drug mixtures tested had higher IC50 values than the hosts. However, the [PdPtL4]4+ cages, and [PdPtL4]4+:drug mixtures were less cytotoxic than the well established anticancer drugs cisplatin, oxaliplatin and 5-fluorouracil. [ABSTRACT FROM AUTHOR]

The surface-microstructural dependent optoelectronic and gas sensing characteristics of Ti-doped CdO thin films spray deposited on tiny glass substrates at 300 °C were examined in depth. XRD measurements revealed the polycrystalline nature of CdO films. It also revealed that the typical crystallite size of CdO films varies between 28 and 41 nm. XPS analysis validated the oxidation status of the Cd, O, and Ti components. The Cd–O metal oxide modes of vibration are confirmed by Raman analysis at ambient temperature. Ti-dopant significantly modifies the surface microstructure of CdO thin films. The predicted optical bandgap of the Ti-doped CdO thin film varies between 2.38 and 2.47 eV. The Ti-doping of 0.75 wt% results in a high typical transparency value of 91%. With a rise in Ti-doping concentration, the charge carrier concentration and resistivity are arbitrarily altered. CdO films with 0.75 wt% Ti had a mobility of 94 cm2 V−1 s−1. For the 0.75 wt% Ti doping, a high figure of merit (152.5 × 10−4 Ω−1) is produced. The formaldehyde gas response of the 0.75 wt% Ti-doped CdO thin film is high (81%). The optical band-gap and degree of crystallinity of CdO thin films are thought to be controlled by Ti dopant. [ABSTRACT FROM AUTHOR]

The assembly of cyclo-pentazolate (cyclo-N5−) anions with counterions has thrived in recent years owing to their potential as high energy density materials. However, high-valence metal pentazolate salts are still rare, thus hindering the recognition of the structures and properties of new metal pentazolate salts. Herein, two trivalent metal pentazolate hydrates, namely, Fe(H2O)6(N5)3·9H2O (1) and Al(H2O)6(N5)3·9H2O (2), were synthesized via a metathesis reaction. The compounds were characterized by infrared spectroscopy, single-crystal X-ray diffraction, electrospray ionization mass spectrometry, elemental analysis, and differential scanning calorimetry. The cyclo-N5− anion decomposition temperature for compound 2 is 141.4 °C, which means it has the highest thermal stability among all cyclo-N5−-based materials reported so far. Single-crystal X-ray analysis revealed that there are no direct σ-bonds between the metal centers and cyclo-N5− anions in the crystal lattices of 1 and 2. Hydrogen bonding and π–π stacking interactions in the crystal lattices of 1 and 2 were evaluated. The proportion of hydrogen bonds is more than 75%. Four kinds of hydrogen bond ring motifs are formed via O–H⋯N and O–H⋯O interactions: tetrameric R 44 (10), pentameric R 55 (12) and R 55 (17), and nonameric R 99 (21) motifs. This study deepens our understanding of the structure of cyclo-N5−-based complexes and is expected to contribute to the further development of pentazole chemistry. [ABSTRACT FROM AUTHOR]

Using the polydentate ligand of H4L with the CoII ion, a triangular prism-type nine-nucleus cluster [Co9(L)3(CH2OCH2OH)6]·3.5H2O ({Co9}-Eg, H4L = 6,6′-(1H,1′H-[3,3′-bi(1,2,4-triazole)]-5,5′-diyl)dipicolinic acid) was constructed. Ion fragmentation during the formation of the {Co9}-Eg cluster was tracked using time-dependent electrospray ionization mass spectrometry. In addition, we proposed two possible formation processes (i) H4L → CoL → Co2L → Co6L3 → Co7L3 → Co9L3 and (ii) H4L → CoL → Co2L → Co3L → Co5L2 → Co7L3 → Co9L3. Magnetic studies show that {Co9}-Eg exhibits slow relaxation under a static zero field at low temperature, which is the main characteristic of single molecule magnets (SMMs). [ABSTRACT FROM AUTHOR]

The reaction of a macrocyclic ligand 1,4,7-triazacyclononane-1,4,7-tripropionic acid (tacntpH3) with Ni(II)/Co(II) sources in the presence or absence of lanthanide cations yielded a series of doubly mononuclear ionic complexes (H3O+)[LnIII(H2O)8][NiII(tacntp)]4 (1-NiLn, Ln = La, Ce, Yb) and a mononuclear Co(III) complex [CoIII(tacntp)]·4H2O (2-Co) incorporating transition metal centers enveloped by both an azamacrocycle ring and pendant carboxylate groups. Either of the two preorganized mononuclear species [MII/III(tacntp)]−/0 was taken as a tripodal 3d metalloligand for the further assembly of modular architectures. Two pentanuclear metallocage-[Ln(NO3)6]3− complexes [Ni II5 (tacntp)2(H2O)12][LnIII(NO3)6]Cl·2H2O (3-NiLn, Ln = La, Ce), one nonanuclear metallocage [Ni II9 (tacntp)4(H2O)18](ClO4)6·10H2O (4-Ni), and two types of 2D layered heterometallic 3d–4f coordination networks ((H3O+)[Ni II2 YbIII(tacntp)2](ClO4)2·3H2O (5-NiYb) and [Co III2 TbIII(tacntp)2(H2O)3](ClO4)·Cl2·5H2O (6-CoLn, Ln = La, Eu, Tb, Dy)) differing largely in their weaving architecture were controllably prepared via the precise regulation of multiple reaction parameters. Furthermore, the time-dependent evolution of metalloligand-derived species was tracked via electrospray ionization-mass spectrometry, to elucidate the modular assembly pathway for the nonanuclear Ni(II) metallocage 4-Ni. Analysis of the structural details and the assembly procedures of the modular architectures revealed that the pH, metalloligand size, and the type of metal bound to the metalloligand considerably influence the structural evolution from mononuclear metalloligands to cage-like and polymeric coordination architectures. Magnetic property studies disclosed that pendant syn–anti carboxylate groups favor a weak ferromagnetic exchange between the adjacent Ni(II) ions within the metallocages of 3-NiLa and 4-Ni but facilitate an antiferromagnetic coupling between the alternating Ni(II) and Yb(III) centers in 5-NiYb. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated the electro-oxidation of diclofenac in methanol using high-performance liquid chromatography/electrospray ionization mass spectroscopy. Information is presented on diclofenac, which is one of the most widely used nonsteroidal anti-inflammatory drugs. Two papers concerning the reaction of diclofenac that occurs upon its degradation called dimerization are also discussed.

Surfactants are hailed as "industrial monosodium glutamate", and are widely used as emulsifiers, demulsifiers, water treatment agents, etc., in the petroleum industry. However, due to the unidirectivity of conventional surfactants, the difficulty in demulsifying petroleum emulsions generated after emulsification with such surfactants increases sharply. Therefore, it is of great significance and application value to design and develop a novel switchable surfactant for oil exploitation. In this study, a CO2-switchable Gemini surfactant of N,N′-dimethyl-N,N′-didodecyl butylene diamine (DMDBA) was synthesized from 1, 4-dibromobutane, dodecylamine, formic acid, and formaldehyde. Then, the synthesized surfactant was structurally characterized by infrared (IR) spectroscopy, hydrogen nuclear magnetic resonance (1H NMR) spectroscopy, and electrospray ionization mass spectrometry (ESI-MS); the changes in conductivity and Zeta potential of DMDBA before and after CO2/N2 injection were also studied. The results show that DMDBA had a good CO2 response and cycle reversibility. The critical micelle concentration (CMC) of cationic surfactant obtained from DMDBA by injecting CO2 was 1.45 × 10−4 mol/L, the surface tension at CMC was 33.4 mN·m−1, and the contact angle with paraffin was less than 90°, indicating that it had a good surface activity and wettability. In addition, the kinetic law of the process of producing surfactant by injecting CO2 was studied, and it was found that the process was a second-order reaction. The influence of temperature and gas velocity on the reaction dynamics was explored. The calculated values from the equation were in good agreement with the measured values, with a correlation coefficient greater than 0.9950. The activation energy measured during the formation of surfactant was Ea = 91.16 kJ/mol. [ABSTRACT FROM AUTHOR]

Worldwide, it is estimated that there are 1.8 to 2.7 million cases of envenoming caused by snakebites. Snake venom is a complex mixture of protein toxins, lipids, small molecules, and salts, with the proteins typically responsible for causing pathology in snakebite victims. For their chemical characterization and identification, analytical methods are required. Reversed-phase liquid chromatography coupled with electrospray ionization mass spectrometry (RP-LC-ESI-MS) is a widely used technique due to its ease of use, sensitivity, and ability to be directly coupled after LC separation. This method allows for the efficient separation of complex mixtures and sensitive detection of analytes. On the other hand, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is also sometimes used, and though it typically requires additional sample preparation steps, it offers desirable suitability for the analysis of larger biomolecules. In this study, seven medically important viperid snake venoms were separated into their respective venom toxins and measured by ESI-MS. In parallel, using nanofractionation analytics, post-column high-resolution fractionation was used to collect the eluting toxins for further processing for MALDI-MS analysis. Our comparative results showed that the deconvoluted snake venom toxin masses were observed with good sensitivity from both ESI-MS and MALDI-MS approaches and presented overlap in the toxin masses recovered (between 25% and 57%, depending on the venom analyzed). The mass range of the toxins detected in high abundance was between 4 and 28 kDa. In total, 39 masses were found in both the ESI-MS and/or MALDI-MS analyses, with most being between 5 and 9 kDa (46%), 13 and 15 kDa (38%), and 24 and 28 kDa (13%) in size. Next to the post-column MS analyses, additional coagulation bioassaying was performed to demonstrate the parallel post-column assessment of venom activity in the workflow. Most nanofractionated venoms exhibited anticoagulant activity, with three venoms additionally exhibiting toxins with clear procoagulant activity (Bothrops asper, Crotalus atrox, and Daboia russelii) observed post-column. The results of this study highlight the complementarity of ESI-MS and MALDI-MS approaches for characterizing snake venom toxins and provide a complementary overview of defined toxin masses found in a diversity of viper snake venoms. [ABSTRACT FROM AUTHOR]

This study investigates the anti-inflammatory, analgesic, and antioxidant properties of polyphenols extracted from Brassica oleracea var. capitata (cabbage) ethanolic extract (BOE). Given the historical use of cabbage in traditional medicine for treating various ailments, this research aims to validate these effects scientifically. The study involved the characterization of BOE's bioactive compounds using Fourier Transform Infrared Spectroscopy (FTIR) and Liquid Chromatography–Diode Array Detection–Electro-Spray Ionization Mass Spectrometry (HPLC-DAD-ESI MS) analysis. We assessed the anti-inflammatory and analgesic effects of topical and oral BOE administration on rodent models with acute and subacute inflammation. Additionally, the antioxidant capacity of orally administered BOE was evaluated. The results showed that BOE possesses significant levels of phenolic compounds with a potent antioxidant activity. The topical administration of BOE demonstrated notable anti-inflammatory effects in the tested rodent models, which were comparable with nonsteroidal anti-inflammatory drugs. These findings suggest that BOE could be a valuable natural remedy for inflammation-related conditions, supporting its traditional uses and highlighting its potential for further pharmacological development. [ABSTRACT FROM AUTHOR]

Cinnamic acid derivatives including 3,5-dimethoxy-4-hydroxycinnamic acid, also referred to as sinapinic acid (SA), are efficient matrices used in matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). Previous findings have shown that Z-sinapinic acid (ZSA) outperforms E-cinnamic acids for carbohydrate (Carb) analysis, probably due to geometry-induced changes in analyte–matrix interactions at the molecular level, prompted by the cinnamic alkene rigid bond. In the present work, direct infusion electrospray ionization mass spectrometry (DI-ESI-MS) experiments were conducted to investigate the behavior of these acids as ligands for neutral Carb non-covalent complex formation. The ionization efficiency and binding affinities of these small molecules were evaluated towards seven Carbs with different monosaccharide composition and length. Experimental results were interpreted with the assistance of computational calculations. ESA, with higher calculated volume and lower acidity than ZSA, exhibited an experimental ESI efficiency similar to the latter. However, titration experiments showed that the [Acid + Carb] gas complex is preferentially formed with ZSA than ESA when both ligands are present in solution. Results from CID experiments support the formation of more stable complexes between larger Carbs and the ZSA isomer compared to the E-form. The change of molecule volume and polarity in the synthesized isotopically labeled ESA, E-3,5-di(methoxy-d3)-4-hydroxycinnamic acid (ESA-d6) used for comparison may explain the lower ESI efficiency obtained with this reference ligand than for ESA. Overall, this combined strategy demonstrated the preferential gas complex formation of Carbs with ZSA, in agreement with the previously proposed matrix–analyte interaction model that explained ZSA differential efficiency as a MALDI matrix. [ABSTRACT FROM AUTHOR]

Iron occurs in plant fluids principally in the form of various low molecular species of which the quantitative determination is hampered by the dynamic equilibria and unavailability of authentic standards. The high-performance liquid chromatography (HPLC) separation of these species is affected by the lability of the complexes and reactivity with the column stationary phase, the phenomena which further affect quantitative analyses. A quantification method based on the in situ formation of isotopically-labelled iron species reflecting their composition in the sample, and hence to be used as internal standards, was developed. The mixture of iron species with the natural and enriched composition was subsequently baseline separated by hydrophilic interaction ion chromatography (HILIC). Each of the species was quantified by either electrospray ionization mass spectrometry (ESI MS) or inductively coupled plasma mass spectrometry (ICP MS) by the comparison of the intensity of peaks corresponding to the molecules containing natural and isotopically-enriched iron. Prior knowledge of the molecular structures of the iron species is not required and hence the need for molecular standards is eliminated. The similar chemistry of isotopically labelled and non-labelled species allowed the correction of the on-column phenomena, such as species retention or degradation, formation of artefacts, or change in sensitivity because of the changing composition of the gradient. The applicability of the method was demonstrated for the quantification of mixed-ligand multicore iron complexes with malate and citrate in coconut water used as a model endosperm liquid. [ABSTRACT FROM AUTHOR]

As a redox-sensitive and multi-species trace element, the chemical behavior of arsenic in various biological sources was closely related to human health. Direct and sensitive speciation analysis of arsenic from complex matrices is ideally required since it enables obtaining multidimensional information concerning arsenic concentration, existing forms, redox states and molecular structures without sample pretreatment. Herein, an online speciation analysis method allowing molecular characterization of both inorganic (As(III), As(V)) and organic arsenic species (MMA, DMA, AsB and AsC) at trace levels from original bio-matrices (e.g. crayfish, laver and kelp) was developed based on ambient ionization mass spectrometry, namely extraction electrospray ionization-hydride generation-microwave plasma torch-mass spectrometry (EESI-HG-MPT-MS). The novel ambient ionization source of MPT was combined with a hydride generator, resulting in a unique mass spectrum behavior for As. By using a home-made sample introduction device and incorporating a HG-MPT, the sensitivity of analytes and matrix tolerance were significantly improved. The detection limits of As(III), As(V), MMA, DMA, AsB and AsC were 0.01, 0.02, 0.08, 0.08, 0.05 and 0.02 μg kg−1 respectively. An online spike experiment was also conducted, showing a recovery of 94–111%, with an RSD less than 10%. The developed method may play a role in studying the chemical or biological behaviors of arsenic in various environments. [ABSTRACT FROM AUTHOR]

This study aimed to develop a rapid and sensitive reversed-phase mode high-performance liquid chromatography-electrospray ionization coupled with a tandem mass spectrometry method for the simultaneous determination of ranolazine enantiomers in rat plasma and tissues. The obtained biological samples were pretreated with the liquid–liquid extraction method, and methyl tert-butyl ether was employed as the extracting agent. The efficient stereo separation of target compounds was achieved on a Chiralcel OD-RH column by using the mobile phase consisting of acetonitrile–2 mM aqueous ammonium acetate (80 : 20, v/v) at a flow rate of 0.6 mL min−1. The analytes were detected by multiple reaction monitoring in positive ion mode with the mass transitions at m/z 428.20 > 279.50 (ranolazine) and 219.80 > 128.06 (ornidazole, internal standard). Furthermore, the elution peak order on the Chiralcel OD-RH column was confirmed by the recorded and calculated electronic circular dichroism spectrum. The results of this pharmacokinetic study revealed that the Cmax and AUC0−t values of R-(+)-ranolazine were 2.05 and 2.72 times higher than those of S-(−)-ranolazine. Compared with S-(−)-ranolazine, R-(+)-ranolazine displayed stronger absorption capability in rat plasma and a slower metabolism rate in major organs of rats. The highest content of R-(+)-ranolazine was in the liver, followed by the kidneys, heart, lungs and spleen. It is noteworthy that this is the first stereoselective report regarding the pharmacokinetics and tissue distribution of ranolazine in vivo, which may benefit instructing the clinical application for safer treatment. [ABSTRACT FROM AUTHOR]

Direct profiling of endogenous biomolecules in tissue samples is considered as a promising approach to investigate metabolic-related toxicity in organisms induced by emerging pollutants. Herein, we report the application of internal extractive electrospray ionization mass spectrometry (iEESI-MS) to direct phospholipid profiling in the liver and spleen tissues of Nile tilapia exposed to perfluorooctanoic acid (PFOA). Combining positive and negative ion detection modes, 130 phospholipid signals were directly detected and identified by iEESI-MS in the tissues of Nile tilapia, including phosphatidyl cholines (PCs), sphingomyelins (SMs), phosphatidic acids (PAs), phosphatidyl ethanolamines (PEs), phosphatidyl glycerols (PGs), phosphatidyl inositols (PIs) and phosphatidyl serines (PSs). With the help of partial least squares discriminant analysis (PLS-DA) and one-way analysis of variance (ANOVA), several phospholipid signals showed a significant difference in the tissue of Nile tilapia between the control group and PFOA exposure groups. In addition, pathway analysis revealed that PFOA has a significant metabolic impact on the glycerophospholipid metabolism in Nile tilapia. Without complex sample preparation, iEESI-MS was applied to direct phospholipid profiling in the liver and spleen tissues of Nile tilapia treated with PFOA, which provided a promising methodology for investigating environmental toxicity and phospholipid-dysregulation caused by emerging pollutants in aquatic organisms. [ABSTRACT FROM AUTHOR]

Photoactivatable Pt(IV) anticancer prodrug trans,trans,trans-[Pt(N3)2(OH)2(pyridine)2] (1) has been shown to bind to and induce oxidation of all four DNA nucleobases. Herein, to further render the binding spectrum of complex 1 to nucleic acids, the interaction between complex 1 and uridine, an exclusive RNA component, was investigated by electrospray ionization mass spectrometry (ESI-MS) and NMR spectroscopy. The results showed that complex 1 can bind to uridine through the N3 (major) and O4 (minor) sites upon light irradiation to form the major mono-platinated uridine adduct and the minor di-platinated uridine adduct. Moreover, mono-platinated uridine associated with the oxidation of uridine to 5-hydroxyuridine and 6-hydroxyuridine was also observed. This is the first report that the photoactivatable Pt(IV) prodrug binds to and induces the oxidation of uridine, and also the last piece of the puzzle for the interactions of complex 1 with nucleobases. Combined with our previous results about the interactions between complex 1 and DNA bases, these data showed a wide interaction spectrum of this kind of photoactivatable diazido Pt(IV) prodrugs with nucleobases through such dual-action modes, strongly suggesting that RNA may be a potential target of Pt(IV) prodrugs. [ABSTRACT FROM AUTHOR]

In order to explore a new method to detect the freshness of lotus seeds, the lotus seeds stored for 0, 1, 2, and 3 years, respectively, were used as experimental materials and analyzed by DAPCI-MS (desorption atmospheric pressure chemical ionization-mass spectrometry). The obtained data were processed by principal component analysis (PCA) and backpropagation artificial neural networks (BP-ANNs). The result showed that DAPCI-MS could obtain abundant chemical material information from the slice surface of lotus seeds. The BP-ANNs model could be applied not only to distinguish fresh and aged lotus seeds with the testing set accuracies of 95.0% and 91.7%, respectively, but also to classify lotus seeds with different storage times with the testing set accuracies of 90.0%, 85.0%, 85.0%, and 90.0%, respectively. The paper developed a fast, convenient, and accurate method for the freshness detection of lotus seed and would provide reliable reference value for rapid authentication of food freshness by the rapid mass spectrometry technique. [ABSTRACT FROM AUTHOR]

Liquid extraction surface analysis (LESA) is a surface sampling technique that allows electrospray mass spectrometry analysis of a wide range of analytes directly from biological substrates. Here, we present LESA mass spectrometry coupled with high field asymmetric waveform ion mobility spectrometry (FAIMS) for the analysis of dried blood spots on filter paper. Incorporation of FAIMS in the workflow enables gas-phase separation of lipid and protein molecular classes, enabling analysis of both haemoglobin and a range of lipids (phosphatidylcholine or phosphatidylethanolamine, and sphingomyelin species) from a single extraction sample. The work has implications for multiplexed clinical assays of multiple analytes. [ABSTRACT FROM AUTHOR]

We herein report the synthesis and characterization of a series of ruthenium-substituted Keggin-type heteropolytungstates containing {RuII(NO)}, {RuIII(H2O)} or {RuIVCl} species. Although anionic [PW11O39RuII(NO)]4− (1) and [PW11O39RuIII(H2O)]4− (2) are known, a new synthetic method for the preparation of (n-Bu4N)4[1] and (n-Bu4N)4[2] is developed in this paper. Treatment of (n-Bu4N)4[XW11O39(Ru≡N)] with Me3NO afforded the ruthenium(ii) nitrosyl complex (n-Bu4N)4[1] in almost quantitative yield. Photolysis of (n-Bu4N)4[1] solution in CH3CN/H2O gives (n-Bu4N)4[2], which is readily oxidized by PhICl2 to yield the RuIV complex (n-Bu4N)4[PW11O39RuIVCl] ((n-Bu4N)4[3]). These complexes are fully characterized by 1H NMR and 31P NMR spectroscopy, infrared spectroscopy, cyclic voltammetry, elemental analysis, thermogravimetric-differential thermal analysis, electrospray ionization mass spectrometry (ESI-MS) and X-ray photoelectron spectroscopy (XPS). [ABSTRACT FROM AUTHOR]

The chlorination of peptides and proteins is an important posttranslational modification, which is a physiological signature of an enzyme myeloperoxidase and can serve as a potential biomarker of some diseases (Parkinson's disease, Alzheimer's disease, etc.). The quantification of the chlorinated peptides has been very challenging in part due to their low levels and artifacts associated with sample preparation. One of the most convenient and promising methods to detect and investigate the chlorinated peptides in the biological samples is the electrospray ionization (ESI) mass spectrometry coupled to the fragmentation techniques (collision-induced dissociation and electron capture dissociation/electron transfer dissociation). We have shown that if the chlorine anions are present in the solution, then the peptide can undergo the chlorination during the ESI ionization. The effect was found to depend on the values of electric potentials of metal parts of the ESI interface. It was found that the grounding of ESI syringe results in the formation of an additional electric loop leading to the electrolytic production of Cl2 and as a consequence the hypochlorous acid inside the ESI needle. Hypochlorous acid reacts with amino groups of peptides and proteins producing chloramine or causing the protein cleavage. In the paper, it is shown on the example of the solution of the several peptides in the presence of HCl that by manipulating the ESI syringe potential, it is possible to create complexes with up to five Cl atoms for sample peptides when the ESI is operated in the positive mode. [ABSTRACT FROM AUTHOR]

Rationale: In‐source decay (ISD) matrix‐assisted laser desorption/ionisation (MALDI) mass spectrometry with a 1,5‐diaminonaphthalene (1,5‐DAN) matrix is used for the structural characterisation of peptides. However, MALDI spectra are intrinsically complicated by the presence of matrix ions, which interfere with the peptide fragments. This may cause false‐positive results or reduced sequence coverage. This paper reports investigations of ISD processes in an intermediate pressure MALDI ion source and a protocol for the removal of interfering ions using ion mobility separation (IMS). Methods: An intermediate pressure MALDI source of a Q‐IMS‐Q‐TOF instrument (Synapt G2) has been employed for the ISD of selected peptides using a 1,5‐DAN matrix. Results: Successful coupling of the MALDI source tuned for ISD experiments using IMS is demonstrated. The IMS made it possible to remove interfering matrix ions effectively from the spectra and thus to increase the confidence of spectral interpretation. Extensive fragment series corresponding to N–Cα bond cleavages were observed under optimised conditions; on the other hand, weaker series of ions caused by peptide bond cleavages were prevalent for default conditions and/or the α‐hydroxycinnamic acid matrix. Conclusions: Ion mobility has been used for the elimination of matrix ions. The technique has been applied to top‐down sequencing of non‐tryptic peptides, such as the human palmitoylated analogue of prolactin‐releasing peptide used in recent obesity studies, and human and insect antimicrobial peptides. [ABSTRACT FROM AUTHOR]

This paper was conducted to develop a method containing ultrahigh performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry for simultaneous quantification of six bioactive components in the decoction of Ziziphi spinosae Semen. Analysis was performed on an Agilent ZORBAX Extend-C18 column (2.1 × 100 mm, 1.8 μm) and eluted with a mobile phase system consisting of acetonitrile and water under a gradient program with a flow rate of 0.3 ml/min. The injection volume was 2 μl. Multiple-reaction monitoring scanning detection was employed for quantification with an electrospray ion source in the negative ion mode. All the six compounds showed good linearities (r≥0.9996). The LODs of the six bioactive compounds were 0.039 ng/ml, 0.092 ng/ml, 3.112 ng/ml, 2.131 ng/ml, 0.099 ng/ml, and 0.071 ng/ml for spinosin, 6‴-feruloylspinosin, jujuboside A, jujuboside B, camelliaside B, and betulinic acid, respectively. The LOQs were 0.118 ng/ml, 0.276 ng/ml, 9.336 ng/ml, 6.393 ng/ml, 0.299 ng/ml, and 0.213 ng/ml for spinosin, 6‴-feruloylspinosin, jujuboside A, jujuboside B, camelliaside B, and betulinic acid, respectively. According to our knowledge, it was the first time to establish a method with high efficiency and accuracy for the quantification of six bioactive components in the decoction of Ziziphi spinosae Semen, which would provide references for quality control and evaluation of Ziziphi spinosae Semen. [ABSTRACT FROM AUTHOR]

The article discusses dual-plating strategy to facilely prepare zinc-bromine Microbatteries (Zn-Br2 MBs) with a liquid cathode to achieve both high areal energy density and fast kinetics. Topics discovered include constructing Zn-Br2 MBs using flexible and hydrophilic carbon nanotube (CNT) paper, the insulating tape and interdigitated electrodes, and theoretical understanding of the advantages of MPIBr.

Poria cocos, with medicinal and edible properties, contains multiple chemical components that pose difficulties in its quality control. Herein, we established a simple thin-layer chromatography spray ionization-mass spectrometry (TLCSI-MS) device that allows the simultaneous separation and identification of bioactive compounds. The triterpene acids in different medicinal parts of Poria cocos were characterized, and the markers of differences were revealed. The quantitative analysis of its pharmaceutical preparation has also been performed to verify the feasibility. The study provides a new analytical perspective for the screening and identification of multiple compounds and a good option for the quality evaluation of herbal medicines and foods. [ABSTRACT FROM AUTHOR]

The analysis of high-valent metal species has been in the focus of research for over 20 years. Mass spectrometry (MS) represents a technique routinely used for their characterization, in particular electrospray ionization mass spectrometry (ESI-MS) and cold-spray ionization-mass spectrometry (CSI-MS). The combination of both methods with tandem MS provides additional tools for understanding decay processes and reaction pathways. In this Perspective, tandem ESI-MS, an important instrument in enzyme and peptide characterization and organometallic chemistry, is discussed as a valuable tool for the elucidation of reaction mechanisms of high-valent metal species. [ABSTRACT FROM AUTHOR]

The cytotoxic activity of a series of dinitrosyl iron complexes (DNICs) with thioureas against cells of different origin has been studied in this work. The cytotoxicity of the studied DNICs proved to be substantially different depending on the structure of the complexes and cell line. Complexes with thiourea and 1,3-dimethylthiourea were found to induce notable cell death in different cell lines of both cancerous and non-cancerous origin, while the N-ethylthiourea-bearing complex induced cell death in cells derived from brain tumors. The studied DNICs effectively release NO while decomposing in solutions, as follows from the electrochemical analysis. It was found that the cytotoxic effects of the studied DNICs did not correlate with their NO-donating ability, hence suggesting that their cytotoxic activity is, in a big part, defined by the long-lived nitrosyl iron–sulfur intermediates formed during the decomposition of the complexes. The structures of the products formed upon hydrolytic decomposition of all studied DNICs have been studied by electrospray ionization mass spectrometry. Stable high-molecular cluster ions containing NO groups namely [Fe4S3(NO)7]− (Roussin's "black salt" anion), [Fe4S3(NO)5]−, [Fe4S4(NO)4]−, [Fe4S3(NO)4]− and [Fe4S3(NO)6]− have been detected in the solution of the N-ethylthiourea-bearing complex. The mechanism of Roussin's "black salt" anion formation in a solution of DNIC with N′-ethylthiourea was studied using density functional theory. This moved us near understanding the reasons for the formation of biologically active intermediates upon the decomposition of the complex with N′-ethylthiourea, which are apparently responsible for the unique antiglioma activity of the complex. [ABSTRACT FROM AUTHOR]