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Volatile organic compounds (VOCs) are carbon-containing molecules with high vapor pressure and low water solubility that are released from biotic and abiotic matrices. Because they are in the gaseous phase, these compounds tend to remain undetected when using conventional metabolomic profiling methods. Despite this omission, efforts to profile VOCs can provide useful information related to metabolic status and identify potential signaling pathways or toxicological impacts in natural or engineered environments. Over the past several decades mass spectrometry (MS) platform innovation has instigated new opportunities for VOC detection from previously intractable matrices. In parallel, volatilome research linking VOC profiles to other forms of multi-omic information (DNA, RNA, protein, and other metabolites) has gained prominence in resolving genotype/phenotype relationships at different levels of biological organization. This review explores both on-line and off-line methods used in VOC profiling with MS from different matrices. On-line methods involve direct sample injection into the MS platform without any prior compound separation, while off-line methods involve chromatographic separation prior to sample injection and analyte detection. Attention is given to the technical evolution of platforms needed for increasingly resolved VOC profiles, tracing technical progress over time with particular emphasis on emerging microbiome and diagnostic applications.

Organophosphorus and organochlorine pesticides, historically or currently widely used in agriculture, are prevalent in the environment and pose significant risks to public health and ecosystems. This study aimed to develop a robust analytical method for quantifying these pesticides in soil and water. By optimizing solid-phase extraction (SPE) and Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) procedures, and utilizing comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOF-MS), we achieved sensitive detection levels of all organophosphorus and organochlorine pesticides at 10 μg/kg for soil and 0.1 μg/kg for water samples. The mean recoveries were in the range of 74.2–118.3 % and 72.3–106.9 % at fortified concentration levels in soil and water, respectively. The method exhibited good linearity (R² ≥ 0.9874) and precision (relative standard deviations from 0.1 % to 29.9 %), providing a reliable approach for environmental monitoring and advancing the capabilities in pesticide residue analysis.

With the development of urbanization and industrialization, more and more chemicals were produced in large quantities and widely used. As a result, they entered the water environment through sewage discharge and agricultural drainage. Currently, the analytical methods of contaminants in water include three main strategies, including target screening, suspect analysis and nontarget screening. The number of compounds identified using target screening methods has increased to hundreds, which is far from meeting the current demand for emerging contaminants (ECs) detection in water environment. To comprehensively screen potential emerging contaminants in the Yangtze River in Jiangsu Province, a nontarget screening strategy combined spectral library search with a molecular network was proposed in Jiangsu-Anhui provincial boundary cross section and 22 drinking water sources in Jiangsu section of Yangtze River. Under this strategy, through spectral library screening using a in-house library, a total of 118 emerging contaminants were identified by accurate mass, isotope distribution and MS/MS fragment ions. These contaminants involved pesticides, herbicides, fungicides, drugs, antibiotics, persistent organic pollutants, flame retardants, plasticizers, indicated active agents, chemical intermediates, and other categories. Since traditional targeted screening relies on commercial standards and screening lists, nontarget screening is a more favorable approach to study ECs and their transformation products in water. Therefore, unannotated chemical substances with similar structures to known contaminants were identified through molecular network technology based on the premise that structurally similar compounds have similar fragment ions. Through using the Global Natural Products Society molecular network (GNPS) to extract molecular families, another contaminant with similar toxicity to amantadine, N-methyl-1-adamantaneamine was found. Furthermore, twenty-three contaminants were confirmed through commercial standard, and 14 of them were detected at a rate of 100%. The quantitative analysis revealed the prevalence of perfluorinated compounds, pharmaceuticals, and personal care products in water bodies, and the total concentrations of the 23 contaminants in each sample ranged from 6.46×102 ng/L to 1.72×103 ng/L. Seven drugs and personal care products were detected. Amantadine was detected at the highest concentration among all locations, and perfluorooctanoic acid (PFOA), amantadine and 2,4-dinitrophenol were detected with the highest mean concentration levels in each location. The nontarget screening strategy using spectral library search and molecular network enabled high-throughput identification of contaminants in water without prior information and standards, in which the structures of unannotated characteristic peaks were inferred from annotated substances with spectral libraries. This strategy will accelerate the systematic discovery of emerging and unknown contaminants in the aqueous environment.

With the rapid development of social economy and the continuous improvement of people’s living standards, the demand for foods of animal origin is also increasing. The problem of veterinary drug residues in foods of animal origin has attracted more and more attention. Meanwhile, higher requirements have been raised for the supervision and inspection of veterinary drug residues. High-resolution mass spectrometry (HRMS) is a powerful tool to retrieve compounds, which can enable the non-targeted screening and confirmation of a variety of veterinary drugs without the use of standards. HRMS is an important technical means for risk monitoring and high-throughput screening of veterinary drug residues, making up for the weaknesses of triple quadrupole mass spectrometry such as poor universality and no ability to screen unknown compounds. This review summarizes the application of liquid chromatography-high resolution mass spectrometry (LC-HRMS) in the field of veterinary drug residue detection from the year 2018 to 2021, and systematically demonstrates the advantages and characteristics of HRMS. With the popularization of HRMS and the development of detection technologies, HRMS will be widely used in the field of veterinary drug residue detection as a routine method.

Characterizing the geochemistry of Europa and Enceladus is a key step for astrobiology investigations looking for evidence of life in their subsurface oceans. Transition metals with several oxidation states, such as iron, may be tracers of the oxidation state of icy ocean moon interiors. Their detection, as well as the characterization of their oxidation states, on the moons’ (plume) ice grains would bring valuable new information about the geochemistry of both the subsurface oceans and surface processes. Impact ionization mass spectrometers such as the SUDA instrument on board Europa Clipper can analyze ice grains ejected from icy moons’ surfaces and detect ocean-derived salts therein. Here we record mass spectra analogs for SUDA using the Laser Induced Liquid Beam Ion Desorption technique for Fe ^2+ and Fe ^3+ salts (both sulfates and chlorides). We show that impact ionization mass spectrometers have the capability to detect and differentiate ferrous (Fe ^2+ ) from ferric (Fe ^3+ ) ions in both cation and anion modes owing to their tendency to form distinct ionic complexes with characteristic spectral features. Peaks bearing Fe ^3+ , such as [Fe ^3+ (OH) _2 ] ^+ and [Fe ^3+ (OH) _a Cl _b ] ^− , are particularly important to discriminate between the two oxidation states of iron in the sample. The recorded analog spectra may allow the characterization of the oxidation state of the oceans of Europa and Enceladus with implications for hydrothermal processes and potential metabolic pathways for life forms in their subsurface oceans.

Cycloalkanes are important components of a wide range of fuels. However, there are few experimental data at simultaneously high temperatures and pressures similar to those found in practical systems. Such data are necessary for developing and testing chemical kinetic models. In this study, data relevant to cycloalkane pyrolysis were obtained from high repetition rate shock tube experiments coupled with synchrotron-based photoionization mass spectrometry diagnostics. The pyrolysis of cyclohexane was studied over 1270–1550 K and ~9 bar, while the more reactive primary decomposition product, 1-hexene, was studied at 1160–1470 K and ~5 bar. Insights into the decomposition of the parent molecules, the formation of primary products and the production of aromatic species were gained. Simulations were performed with models for cyclohexane and 1-hexene that were based on literature models. The results indicate that over several hundred microseconds reaction time at high pressures and temperatures the pyrolysis of cyclohexane is largely dominated by reactions initiated by cyclohexyl radicals. Furthermore, good agreement between the simulations and the experiments were observed for cyclohexane and 1-hexene with a modified version of the cyclohexane model. Conversely, the 1-hexene model did not reproduce the experimental observations.

Dithiolopyrrolone antibiotics, produced by the Saharan mycelial bacterium Saccharothrix algeriensis, are known for their potent biological activities. Biochemical profiling of S. algeriensis culture extract was done by direct analysis in real time and time-of-flight mass spectrometry (DART-ToF-MS). No other study on dithiolopyrrolones by this technique has been published. Eleven dithiolopyrrolone derivatives: thiolutin, butyryl-pyrrothine/iso-butyryl-pyrrothine, senecioyl-pyrrothine/tigloyl-pyrrothine, valeryl-pyrrothine/iso-valeryl-pyrrothine, 2-methyl-3-pentenyl-pyrrothine/2-hexonyl-pyrrothine, iso-hexanoyl-pyrrothine and benzoyl-pyrrothine were characterised by their exact mass measurement and the corresponding molecular formula of each compound. The obtained results confirmed that DART-ToF-MS is an appropriate confirmatory technique for powerful and rapid screening, as well as characterisation of bacterial secondary metabolites.

The present research is focused on the development of a green and sustainable analytical method, based on the use of headspace solid-phase microextraction (HS SPME), and hydrogen as carrier gas, within the context of fast flow-modulation comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (FM GC × GC-ToFMS), for the investigation of the volatile composition of Capsicum peppers. In such a respect, three different species were analysed: Annuum, Baccatum, and Chinense. Following HS SPME FM GC × GC-ToFMS analysis, a tile-based Fisher-ratio software was used to easily determine compounds that varied the most within the same variety of Capsicum samples. Particular emphasis was also devoted to the aroma profile of the thirty most sample-distinguishing compounds.

SWATHtoMRM technology was used in this experiment to further identify and trace the sources of Dendrobium devonianum and Dendrobium officinale produced in the same area using TOF and MS-MRM. After the conversion of the R package of SWATHtoMRM, 191 MRM pairs of positive ions and 96 pairs of negative ions were obtained. Dendrobium devonianum and Dendrobium officinale can be separated very well using the PCA and PLS-DA analysis of MRM ion pairs; this shows that there are obvious differences in chemical composition between Dendrobium devonianum and Dendrobium officinale, which clearly proves that the pseudotargeted metabolomics method based on SWATHtoMRM can be used for traceability identification research. A total of 146 characteristic compounds were obtained, with 20 characteristic compounds in Dendrobium devonianum. The enrichment pathways of the characteristic compounds were mainly concentrated in lipids and atherosclerosis, chagas disease, fluid shear stress and atherosclerosis, proteoglycans in cancer, the IL-17 signaling pathway, the sphingolipid signaling pathway, diabetic cardiomyopathy, arginine and proline metabolism, etc., among which the lipid and atherosclerosis pathways were more enriched, and 11 characteristic compounds affected the expression levels of IL-1, TNFα, CD36, IL-1β, etc. These can be used as a reference for research on variety improvement and active substance accumulation in Dendrobium devonianum and Dendrobium officinale.

Comprehensive three-dimensional (3D) gas chromatography (GC3) coupled to time-of-flight-mass spectrometry (GC3-TOFMS) is an intriguing extension of the well-established comprehensive two-dimensional gas chromatography (GC×GC) technique. Although impressive gains have been made in the instrumentation realm, the utility of non-targeted chemometric analysis of GC3-TOFMS data has yet to be explored. Herein, we present the first application of principal component analysis (PCA) to a GC3-TOFMS dataset of jet fuel samples. Five replicates each of four jet fuels (JP8, J1800A, JP4, and JP7) were collected by GC3-TOFMS with commercial thermal modulation from the first-dimension column (1D) to the second-dimension column (2D), and dynamic pressure gradient modulation (DPGM) from the 2D column to the third-dimension column (3D), thus providing full mass transfer (100% duty cycle both modulation stages). A novel re-registration technique is introduced in which a user-selected series of vacant 3D modulations are removed to correct 2D shifting and effectively “center” the data. This shifting has consistently been observed in the 2D versus 1D view of GC3-TOFMS chromatograms, likely due to the slowed flow on 2D in DPGM and/or temperature programming effects. The 3D PCA loadings of the re-registered data revealed subtle chemical differences between the fuels which would not be as easily elucidated using PCA of GC×GC data. Finally, PCA of the two most chemically similar fuels (J1800A and JP7) revealed additional chemical differences which were drowned out in the initial multi-fuel PCA model, highlighting the potential advantage of “pairwise” PCA for multi-class GC3-TOFMS datasets.

This paper describes methodology based on the application of isotope dilution (ID) in single-particle inductively coupled plasma time-of-flight mass spectrometry (spICP-ToFMS) mode for the mass determination (and sizing) of silver nanoparticles (AgNPs). For this purpose, and considering that the analytical signal in spICP-MS shows a transient nature, an isotope dilution equation used for online work was adapted and used for the mass determination of individual NPs. The method proposed measures NP isotope ratios in a particle-to-particle approach, which allows for the characterization of NP mass (and size) distributions and not only the mean size of the distribution. For the best results to be obtained, our method development (undertaken through the analysis of the reference material NIST RM 8017) included the optimization of the working conditions for the best precision and accuracy in isotope ratios of individual NPs, which had been only reported to date with multicollector instruments. It is shown that the precision of the measurement of these ratios is limited by the magnitude of the signals obtained for each NP in the mass analyzer (counting statistics). However, the uncertainty obtained for the sizing of NPs in this approach can be improved by careful method optimization, where the most important parameters are shown to be the selection of the spike isotopic composition and concentration. Although only AgNPs were targeted in this study, the method presented, with the corresponding adaptations, could be applied to NPs of any other composition that include an element with different naturally available isotopes.

Pears (Pyrus communis L.) and apples (Malus domestica Borkh.) are two of the most popular fruits worldwide. The phenolic compounds they offer are associated with human health benefits due to their antioxidant properties. Since these fruits’ by-products are not yet fully exploited, it is important to characterize them, especially in terms of their antioxidant properties. The aim of this study was to determine the antioxidant properties of old traditional cultivars, six regional pear cultivars and five regional apple cultivars grown in the Alcobaça region (Portugal). Antioxidant capacity assays were used to evaluate the antioxidant properties. Generally, the antioxidant capacity, total phenolics content (TPC), and total flavonoids content (TFC) of fruit byproducts (both seeds and peels) were higher than the corresponding mesocarp, indicating their potential as sources of beneficial antioxidant compounds. Moreover, a UHPLC-ToF-MS method was optimized and validated in order to quantify 21 distinct phenolics in these fruit samples. The analytical method’s suitability for quantifying phenolic compounds was demonstrated by an evaluation of linearity, limit of detection, limit of quantification, precision and accuracy. This method was used to determine the phenolic composition of samples of regional (local) cultivars. The phenolics in the fruit samples with the highest concentrations were phlorizin and chlorogenic acid. Principal component analysis (PCA) was used to separate distinct fruit species while emphasizing their similarities and differences.

Herbal infusions are highly popular beverages consumed daily due to their health benefits and antioxidant properties. However, the presence of plant toxins, such as tropane alkaloids, constitutes a recent health concern for herbal infusions. This work presents an optimized and validated methodology based on the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) extraction procedure followed by Ultra-High Performance Liquid Chromatography combined with Time-of-Flight Mass Spectrometry (UHPLC-ToF-MS) for the determination of tropane alkaloids (atropine, scopolamine, anisodamine, and homatropine) in herbal infusions, in accordance with criteria established by Commission Recommendation EU No. 2015/976. One of the seventeen samples was contaminated with atropine, exceeding the current European regulation regarding tropane alkaloids. In addition, this study evaluated the antioxidant capacity of common herbal infusions available on Portuguese markets, indicating the high antioxidant capacity of yerba mate (Ilex paraguariensis), lemon balm (Melissa officinalis), and peppermint (Mentha x piperita).

Objective of the work was to conduct an extended study of Legionella strains isolated from epidemiologically significant environmental objects during the preparation and conduct of mass events in the territory of the Russian Federation in 2013-2014 . Materials and methods. Studied were 53 strains of Legionella pneumophila, isolated from epidemiologically significant objects during the preparation and conduct of a number of mass events (ME): XXVII World Summer Universiade, XXII Olympic Winter Games and XI Paralympic Winter Games, Sochi; Summer Health Promotion Campaign in 2014, Republic of Crimea; IV Caspian Summit, Astrakhan, 2014. Strains were analyzed using multilocus sequencing, time-of-flight mass spectrometry (MALDI-ToF-MS) and atomic force microscopy. Legionella strains were typed by multilocus sequencing in accordance with the algorithm of the European Legionellosis Research Group “Sequence-Based Typing protocol for epidemiological typing of L. pneumophila". Results and discussion. Strains of L. pneumophila, legionellosis agent, were isolated in the territory of the Republic of Crimea, Moscow, Kazan, Sochi, Astrakhan and characterized. According to the results of slide agglutination, 17 L. pneumophila strains were assigned to 1 serogroup , 37 - to 2-14 serogroups. Based on the data obtained by multilocus sequencing, in accordance with the algorithm of the European Working Group on Legionellosis Surveillance, allelic profiles of all the studied L. pneumophila strains were identified; their belonging to 7 sequence types was established. Using the method of time-of-flight mass spectrometry, legionella strains were characterized, their protein profiles were studied, and a database was formed. Using the method of scanning probe microscopy, information was obtained on the morphology of the cells of 18 legionella strains and the features of their surface structures. Using the methods of multilocus sequencing, time-of-flight mass spectrometry, and atomic force microscopy, molecular-genetic, proteomic, and morphometric features of Legionellosis pathogen strains that circulate in epidemiologically significant sites in the Russian Federation were determined.

Sensitive gas analyses, in particular in industrial processes, are nowadays performed either via spectroscopy or using quadrupole mass spectrometers; the first method provides a fast but indirect measurement, whereas the second provides in situ measurements of only one species at a time. In this article, we present a novel time-of-flight residual gas analyzer (TOF-RGA) built by the Swiss company Spacetek Technology AG, and show the results of measurements such as the characterization of the FC5311 calibration compound, the detection of naturally abundant noble gases in air, the measurement of a noble gas mixture in the ultra-high vacuum facilities of CERN, and measurements acquired in a X-ray Photoelectron Spectroscopy facility in Germany, to demonstrate the capability of this new TOF-RGA to compete with already existing techniques for the monitoring of the composition of gases in real time (10 times per second), at high resolution (m/?m = 1 200 measured at m/z 132), and with a high sensitivity at ppb level.

Over the past decade, the technical requirements of analytical instrumentation have continuously risen driven by the demand for increasingly complex and demanding applications. TOFWERK, a Swiss company with the headquarters in Thun, has been at the forefront of this development by producing modular and ruggedized Time-Of-Flight Mass Spectrometers (TOFMS). They are often used to replace quadrupole mass analysers with more powerful TOF mass analysers. Starting with first customers in atmospheric sciences, TOFWERK TOFMS are now used across a wide range of research areas and lately also in industry. Here we present an overview of mobile applications in which Tofwerk TOFMS are in operation while moved around in space.

A new gas inlet port combined with a novel ionization scheme have been developed and coupled to a high-resolution time-of-flight mass spectrometer (TOF MS) for the detection and measurement of atmospheric volatile (VOCs) and intermediate volatility organic compounds (IVOCs). Ions are produced predominantly by charge transfer reactions in a low-temperature plasma ionization source with minimal fragmentation. Enhanced sensitivity is accomplished by incorporating an increased-size inlet capillary in a transverse arrangement to maximize throughput in the ionization source. Additional design aspects of the new mass spectrometer enabling superior transmission include a large acceptance ion funnel and a segmented radio frequency (RF) ion guide with increased space charge storage capacity. An orthogonal TOF analyzer equipped with a two-stage reflectron and tuned to second order is employed for the determination of the mass-to-charge ratio of the ions, with a mass resolving power of >20 k at mass 500 Th. The performance of the instrument was evaluated in tests using VOC standards and in atmospheric chamber experiments to demonstrate the ability to measure a wide range of organic compounds with different functional groups. Linear signal response is demonstrated over a wide range of VOCs used in the calibration processes in the ppb range, while the instrument exhibits linear response in the ppt range as well. Detection limits as low as 1 ppt are accomplished. The potential applications of this new TOF MS instrument were demonstrated in a pilot atmospheric simulation chamber experiment.

Summary: Mass spectrometry is a widespread approach used to work out what the constituents of a material are. Atoms and molecules are removed from the material and collected, and subsequently, a critical step is to infer their correct identities based on patterns formed in their mass-to-charge ratios and relative isotopic abundances. However, this identification step still mainly relies on individual users' expertise, making its standardization challenging, and hindering efficient data processing. Here, we introduce an approach that leverages modern machine learning technique to identify peak patterns in time-of-flight mass spectra within microseconds, outperforming human users without loss of accuracy. Our approach is cross-validated on mass spectra generated from different time-of-flight mass spectrometry (ToF-MS) techniques, offering the ToF-MS community an open-source, intelligent mass spectra analysis. The bigger picture: Time-of-flight mass spectrometry (ToF-MS) is a mainstream analytical technique widely used in biology, chemistry, and materials science. ToF-MS provides quantitative compositional analysis with high sensitivity across a wide dynamic range of mass-to-charge ratios. A critical step in ToF-MS is to infer the identity of the detected ions. Here, we introduce a machine-learning-enhanced algorithm to provide a user-independent approach to performing this identification using patterns from the natural isotopic abundances of individual atomic and molecular ions, without human labeling or prior knowledge of composition. Results from several materials and techniques are compared with those obtained by field experts. Our open-source, easy-to-implement, reliable analytic method accelerates this identification process. A wide range of ToF-MS-based applications can benefit from our approach, e.g., hunting for patterns of biomarkers or for contamination on solid surfaces in high-throughput data.

Coffee, one of the most popular beverages in the world, attracts consumers by its rich aroma and the stimulating effect of caffeine. Increasing consumers prefer decaffeinated coffee to regular coffee due to health concerns. There are some main decaffeination methods commonly used by commercial coffee producers for decades. However, a certain amount of the aroma precursors can be removed together with caffeine, which could cause a thin taste of decaffeinated coffee. To understand the difference between regular and decaffeinated coffee from the volatile composition point of view, headspace solid-phase microextraction two-dimensional gas chromatography time-of-flight mass spectrometry (HS-SPME-GC×GC-TOFMS) was employed to examine the headspace volatiles of eight pairs of regular and decaffeinated coffees in this study. Using the key aroma-related volatiles, decaffeinated coffee was significantly separated from regular coffee by principal component analysis (PCA). Using feature-selection tools (univariate analysis: t-test and multivariate analysis: partial least squares-discriminant analysis (PLS-DA)), a group of pyrazines was observed to be significantly different between regular coffee and decaffeinated coffee. Pyrazines were more enriched in the regular coffee, which was due to the reduction of sucrose during the decaffeination process. The reduction of pyrazines led to a lack of nutty, roasted, chocolate, earthy, and musty aroma in the decaffeinated coffee. For the non-targeted analysis, the random forest (RF) classification algorithm was used to select the most important features that could enable a distinct classification between the two coffee types. In total, 20 discriminatory features were identified. The results suggested that pyrazine-derived compounds were a strong marker for the regular coffee group whereas furan-derived compounds were a strong marker for the decaffeinated coffee samples.

Objective: To isolate and identify chemical compounds in Harak, a Thai herbal formula widely used as an antipyretic drug in Thailand. Methods: Methanol extraction of the Harak formula and its five herbal components were separated by Ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. This method has been developed for “untargeted” profiling of this formula and its components. An online database was used to identify chemical compounds by comparing its empirical molecular formula, isotope pattern, and fragmentation pattern. Results: Nineteen chemical constituents were found from positive and negative electrospray ionization (ESI) modes. These compounds included flavonoids, hesperitine, and iso-corydine, which are known to possess antioxidant and anticancer activity. Moreover, data from the principle component analysis (PCA) score plot of positive and negative ESI modes showed that the chemical constituents of Thai herbal Harak formula were similar to those found in Ficus racemosa Linn. and Capparis micracantha DC. Conclusion: Under this optimization method, nineteen chemical constituents including phenolic and flavonoids were characterized in both positive and negative ESI mode.

Toxins - molecular weight compounds produced by microorganisms, animals, plants and possessing antigene properties. Recently due to the perceived threat of terrorist actions identification of a number of bacterial toxins is especially important. A new approach in the identification of toxins associated with the development of mass spectrometry and can be successfully used for analysis of most environmental toxins. The method of MALDI-MS allows the detection of toxins such as Shiga-toxin Escherichia coli, delta-toxin of Staphylococcus aureus, Bacillus cereus particular, botulinum neurotoxin, cholera toxin. Analytical and diagnostic characteristics of the method, the simplicity and speed studies indicate the long term implementation of a method in the practice of laboratory diagnostics in determining toxinproducing of the studied microorganisms.

MicroRNAs, which circulate in blood, are characterized by high diagnostic value; in biomedical research, they can be considered as candidate markers of various diseases. Mature microRNAs of glial cells and neurons can cross the blood–brain barrier and can be detected in the serum of patients with autism spectrum disorders (ASD) as components of macrovesicles, macromolecular protein and low-density lipoprotein particles. In our present study, we have proposed an approach, in which microRNAs in protein complexes can be concentrated on the surface of AFM chips with oligonucleotide molecular probes, specific against the target microRNAs. MicroRNAs, associated with the development of ASD in children, were selected as targets. The chips with immobilized molecular probes were incubated in serum samples of ASD patients and healthy volunteers. By atomic force microscopy (AFM), objects on the AFM chip surface have been revealed after incubation in the serum samples. The height of these objects amounted to 10 nm and 6 nm in the case of samples of ASD patients and healthy volunteers, respectively. MALDI-TOF-MS analysis of protein components on the chip surface allowed us to identify several cell proteins. These proteins are involved in the binding of nucleic acids (GBG10, RT24, RALYL), in the organization of proteasomes and nucleosomes (PSA4, NP1L4), and participate in the functioning of the channel of active potassium transport (KCNE5, KCNV2).

Abstract Background Polydrug abuse is a known problem among opioid-dependent patients receiving opioid maintenance treatment (OMT). However, improved laboratory diagnostics is required to reveal polydrug abuse in its current scope. Furthermore, there are few studies focusing on the relationship between polydrug abuse and adequacy of the dose of OMT medicine. This study aimed to evaluate the polydrug abuse among opioid-dependent patients receiving OMT with inadequate (Group IA) and adequate (Group A) doses of OMT medicine as experienced by the patients. Craving for opioids and withdrawal symptoms were evaluated as indicators of the adequacy rating. Methods This is a retrospective register-based study of 60 OMT patients on either methadone or sublingual buprenorphine/naloxone medication, whose polydrug abuse was studied from urine samples by means of a comprehensive high-resolution mass spectrometry method. Results Inadequate doses of the OMT medicines were associated with higher subjective withdrawal scores and craving for opioids. Six groups of abused substances (benzodiazepines, amphetamines, opioids, cannabis, new psychoactive substances, and non-prescribed psychotropic medicines) were found among OMT patients. Group IA patients showed significantly more abuse of benzodiazepines and amphetamines than the Group A patients. All the new psychoactive substances and most of the non-prescribed psychotropic medicines were detected from the Group IA patients. There was no difference in the doses of the OMT medicine between Groups IA and A patients. Conclusions Polydrug abuse, detected by definitive laboratory methods, was widespread and more common among Group IA than Group A patients, emphasizing the requirement for individual OMT medicine dose adjustment.

This study applied an untargeted–targeted (UT) fingerprinting approach, based on comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOF MS), to assess the effects of rainfall and temperature (both seasonal and elevational) on the tea metabolome. By this strategy, the same compound found in multiple samples need only to be identified once, since chromatograms and mass spectral features are aligned in the data analysis process. Primary and specialized metabolites of leaves from two Chinese provinces, Yunnan (pu′erh) and Fujian (oolong), and a farm in South Carolina (USA, black tea) were studied. UT fingerprinting provided insight into plant metabolism activation/inhibition, taste and trigeminal sensations, and antioxidant properties, not easily attained by other analytical approaches. For example, pu′erh and oolong contained higher relative amounts of amino acids, organic acids, and sugars. Conversely, black tea contained less of all targeted compounds except fructose and glucose, which were more similar to oolong tea. Findings revealed compounds statistically different between spring (pre-monsoon) and summer (monsoon) in pu′erh and oolong teas as well as compounds that exhibited the greatest variability due to seasonal and elevational differences. The UT fingerprinting approach offered unique insights into how differences in growing conditions and commercial processing affect the nutritional benefits and sensory characteristics of tea beverages.

Due to the rapid development of nanotechnologies, engineered nanomaterials (ENMs) and nanoparticles (ENPs) are becoming a part of everyday life: nanotechnologies are quickly migrating from laboratory benches to store shelves and industrial processes. As the use of ENPs continues to expand, their release into the environment is unavoidable; however, understanding the mechanisms and degree of ENP release is only possible through direct detection of these nanospecies in relevant matrices and at realistic concentrations. Key analytical requirements for quantitative detection of ENPs include high sensitivity to detect small particles at low total mass concentrations and the need to separate signals of ENPs from a background of dissolved elemental species and natural nanoparticles (NNPs). To this end, an emerging method called single-particle inductively coupled plasma mass spectrometry (sp-ICPMS) has demonstrated great potential for the characterization of inorganic nanoparticles (NPs) at environmentally relevant concentrations. Here, we comment on the capabilities of modern sp-ICPMS analysis with particular focus on the measurement possibilities offered by ICP-time-of-flight mass spectrometry (ICP-TOFMS). ICP-TOFMS delivers complete elemental mass spectra for individual NPs, which allows for high-throughput, untargeted quantitative analysis of dispersed NPs in natural matrices. Moreover, the multi-element detection capabilities of ICP-TOFMS enable new NP-analysis strategies, including online calibration via microdroplets for accurate NP mass quantification and matrix compensation.

An analytical procedure is proposed for determining three cyanotoxins (microcystin RR, microcystin LR, and nodularin) and two phycotoxins (domoic and okadaic acids) in seawater and algae-based food supplements. The toxins were first isolated by a salting out liquid extraction procedure. Since the concentration expected in the samples was very low, a dispersive liquid–liquid microextraction procedure was included for preconcentration. The ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate (80 mg) was used as green extractant solvent and acetonitrile as disperser solvent (0.5 mL) for a 10 mL sample volume at pH 1.5, following the principles of green analytical chemistry. Liquid chromatography with electrospray ionization and quadrupole time of flight-mass spectrometry (LC-Q-TOF-MS) was used. The selectivity of the detection system, based on accurate mass measurements, allowed the toxins to be unequivocally identified. Mass spectra for quadrupole time of flight-mass spectrometry (Q-TOF-MS) and Q-TOF-MS/MS were recorded in the positive ion mode and quantification was based on the protonated molecule. Retention times ranged between 6.2 and 18.3 min using a mobile phase composed by a mixture of methanol and formic acid (0.1%). None of the target toxins were detected in any of the seawater samples analyzed, above their corresponding detection limits. However, microcystin LR was detected in the blue green alga sample.

Positive photoresists are widely used in lithographic process in microelectronics and in optics for the fabrication of relief components. With the aim of identifying molecular modifications among positive photoresists unexposed and previously exposed to ultraviolet light the electron stimulated ion desorption technique coupled to time-of-flight mass spectrometry was employed in the study of the AZ-1518 photoresist. Mass spectra were obtained as a function of the electron beam energy, showing specific changes related to the photochemical decomposition of the photoresist. This reinforces the applicability of the technique to investigate and characterize structural changes in photosensitive materials.

The photodissociation of small organic molecules, namely methyl iodide, methyl bromide, and methyl chloride, adsorbed on a metal surface was investigated in real time by means of femtosecond-laser pump–probe mass spectrometry. A weakly interacting gold surface was employed as substrate because the intact adsorption of the methyl halide molecules was desired prior to photoexcitation. The gold surface was prepared as an ultrathin film on Mo(100). The molecular adsorption behavior was characterized by coverage dependent temperature programmed desorption spectroscopy. Submonolayer preparations were irradiated with UV light of 266 nm wavelength and the subsequently emerging methyl fragments were probed by photoionization and mass spectrometric detection. A strong dependence of the excitation mechanism and the light-induced dynamics on the type of molecule was observed. Possible photoexcitation mechanisms included direct photoexcitation to the dissociative A-band of the methyl halide molecules as well as the attachment of surface-emitted electrons with transient negative ion formation and subsequent molecular fragmentation. Both reaction pathways were energetically possible in the case of methyl iodide, yet, no methyl fragments were observed. As a likely explanation, the rapid quenching of the excited states prior to fragmentation is proposed. This quenching mechanism could be prevented by modification of the gold surface through pre-adsorption of iodine atoms. In contrast, the A-band of methyl bromide was not energetically directly accessible through 266 nm excitation. Nevertheless, the one-photon-induced dissociation was observed in the case of methyl bromide. This was interpreted as being due to a considerable energetic down-shift of the electronic A-band states of methyl bromide by about 1.5 eV through interaction with the gold substrate. Finally, for methyl chloride no photofragmentation could be detected at all.

Proanthocyanidins are complex polymers of flavan-3-ol monomers and play a key sensory and health role in foods and beverages. We describe here a novel method for characterizing wine proanthocyanidins using a theoretical database comprised of the chemical formula and exact mass of 996 compounds. The database was constructed using the four primary grape and wine proanthocyanidin monomers: (epi)catechin, (epi)catechin-3-O-gallate, (epi)gallocatechin, and (epi)gallocatechin-3-O-gallate, each combined in all possible combinations up to a polymerization of 10. The database was queried against spectra collected using ultrahigh performance liquid chromatography (UHLPC) with a hydrophilic interaction liquid chromatography (HILIC) column and coupled to a high-resolution accurate mass quadrupole time-of-flight mass spectrometer (Q-TOF MS). Two wine samples produced with different post fermentation maceration were analyzed using the presented method to demonstrate application for analysis of diverse proanthocyanidins. The first sample was pressed immediately at the end of fermentation when all sugar had been utilized and the second received eight weeks of post fermentation maceration. The HILIC column combined with high resolution tandem mass spectrometry and database matching provided tentative identification of 89 compounds with excellent resolution and without the need for two-dimensional separations. The identified compounds were visualized with Kendrick mass analysis, a simple technique allowing for rapid visualization of which compounds are present in a given sample.

Matrix-assisted laser desorption/ionization (MALDI), a soft ionization method, coupling with time-of-flight mass spectrometry (TOF MS) has become an indispensible tool for analyzing macromolecules, such as peptides, proteins, nucleic acids and polymers. However, the application of MALDI for the analysis of small molecules (

Natural products still constitute a prolific source of lead compounds for the development of novel drugs. Due to their unmatched structural diversity they represent an indispensable complement to synthetic compound collections and virtual libraries. However, the tremendous changes which have taken place in the drug discovery process over the last decade have introduced completely new requirements for natural product research. The classical bioactivity-guided approach no longer matches the timelines and the workflow of modern drug discovery. More targeted approaches are needed in order to identify promising candidate molecules at an early stage, and to accelerate the follow-up process. We describe herein our strategy for tracking bioactive components in complex mixtures, and discuss the potential of accurate mass measurements for natural product identification and the impact of mass-controlled preparative HPLC on the isolation process of bioactive compounds.