Use Of High-resolution Mass Spectrometry Research Articles

The construction of Z-scheme heterojunction ZnIn2S4@CuO with enhanced charge transfer capability and its mechanism study for the visible light degradation of tetracycline

In this study, copper oxide (CuO) was prepared by the microwave-assisted hydrothermal technique subsequently, CuO was grown in situ onto different rare metal compounds to prepare Z-scheme heterojunctions to improve the degradation efficiency of tetracycline (TC) in water environments. Various characterization proved the successful synthesis of all composite materials, and the formation of tight heterojunction interfaces, among which, the core–shell structure ZnIn2S4@CuO exhibited excellent photocatalytic degradation capability. Research results indicated that the degradation efficiency of ZnIn2S4@CuO for TC (50 mg/L) in the water environment reached 95.8 %, and the degradation rate is 2.41 times and 12.93 times that of CuO and ZnIn2S4 alone, respectively, the reason is because of the introduction of ZnIn2S4, Z-scheme heterojunction structures and internal electric field (IEF) is constructed and formed to extend the visible light response range of photocatalysts to improve electron-hole separation efficiency, and enhance charge transfer. In addition, ZnIn2S4@CuO-2 exhibited good stability and reproducibility, with no significant loss of activity after five cycles. Finally, the precise locations of free radical attack on TC were investigated by the combined use of high-resolution mass spectrometry (HR-MC) and frontier electron densities (FEDs), and a reasonable degradation pathway was provided. The results of this research provide a new and viable approach to overcome the limitations of conventional photocatalytic materials in terms of limited visible light absorption range and fast carrier recombination rates, which offers promising prospects for a wide range of applications in the field of wastewater purification.

Per- and Polyfluoroalkyl Substances (PFAS) or Interference? Using High-Resolution Mass Spectrometry as an Investigative Tool in Food Analysis

Accurate quantification of per- and polyfluoroalkyl substances (PFAS) in food is necessary to understand potential dietary exposure. While beneficial for most applications, quantification of PFAS using low-resolution triple quadrupole instruments can be complicated by the presence of co-eluted interferences, which can result in false positives or inaccurate PFAS concentrations. This article discusses the use of high-resolution mass spectrometry (HRMS) to distinguish between matrix interferences and PFAS compounds in a variety of food matrices, and incorporation of these interferences into routine triple quadrupole methods for monitoring.

Review of analytical methods for screening and quantification of fentanyl analogs and novel synthetic opioids in biological specimens.

Fentanyl, fentanyl analogs, and other novel synthetic opioids (NSO), including nitazene analogs, prevail in forensic toxicology casework. Analytical methods for identifying these drugs in biological specimens need to be robust, sensitive, and specific. Isomers, new analogs, and slight differences in structural modifications necessitate the use of high-resolution mass spectrometry (HRMS), especially as a non-targeted screening method designed to detect newly emerging drugs. Traditional forensic toxicology workflows, such as immunoassay and gas chromatography mass spectrometry (GC-MS), are generally not sensitive enough for detection of NSOs due to observed low (sub-μg/L) concentrations. For this review, the authors tabulated, reviewed, and summarized analytical methods from 2010-2022 for screening and quantification of fentanyl analogs and other NSOs in biological specimens using a variety of different instruments and sample preparation approaches. Limits of detection or quantification for 105 methods were included and compared to published standards and guidelines for suggested scope and sensitivity in forensic toxicology casework. Methods were summarized by instrument for screening and quantitative methods for fentanyl analogs and for nitazenes and other NSO. Toxicological testing for fentanyl analogs and NSOs is increasingly and most commonly being conducted using a variety of liquid chromatography mass spectrometry (LC-MS)-based techniques. Most of the recent analytical methods reviewed exhibited limits of detection well below 1 μg/L to detect low concentrations of increasingly potent drugs. In addition, it was observed that most newly developed methods are now using smaller sample volumes which is achievable due to the sensitivity increase gained by new technology and new instrumentation.

Use of high-resolution mass spectrometry for veterinary drug multi-residue analysis

National and international food and feed safety authorities are shifting from routine-to risk-based monitoring. Risk-based monitoring requires flexibility in the scope of analytes, matrices, and sampling. Also, risk-based monitoring implies a desire for retrospective analysis using different scope(s) to follow trends, identify new food safety threats, and monitor the effectiveness of policy interventions. The current availability of sensitive and accurate high-resolution mass spectrometry (HRMS) fits within this approach. This writing reviews the applicability of HRMS techniques for food control laboratories in the analysis of veterinary medicinal products and hormones in food, using HRMS and legislative background. Different HRMS measurement and data evaluation strategies are identified and discussed. Among them, routine screening and confirmation, suspect screening, semi-untargeted analysis (common mass pattern search), metabolite and degradation product identification, profiling for deviating samples, physiological markers or treatments, and identification of unknowns can be found. The food safety competent authorities could shift from methods with predefined scope to real risk-based monitoring by implementing HRMS for routine food and feed analysis.

Heterogeneous chemistry of ozone with floor cleaning agent: Implications of secondary VOCs in the indoor environment

Human daily activities such as cooking, and cleaning can affect the indoor air quality by releasing primary emitted volatile organic compounds (VOCs), as well as by the secondary product compounds formed through reactions with ozone (O3) and hydroxyl radicals (OH). However, our knowledge about the formation processes of the secondary VOCs is still incomplete. We performed real-time measurements of primary VOCs released by commercial floor-cleaning detergent and the secondary product compounds formed by heterogeneous reaction of O3 with the constituents of the cleaning agent by use of high-resolution mass spectrometry. We measured the uptake coefficients of O3 on the cleaning detergent at different relative humidities in dark and under different light intensities (320 nm < λ < 400 nm) relevant for the indoor environment. On the basis of the detected compounds we developed tentative reaction mechanisms describing the formation of the secondary VOCs. Intriguingly, under light irradiation the formation of valeraldehyde was observed based on the photosensitized chemistry of acetophenone which is a constituent of the cleaning agent. Finally, we modeled the observed mixing ratios of three aldehydes, glyoxal, methylglyoxal, and 4-oxopentanal with respect to real-life indoor environment. The results suggest that secondary VOCs initiated by ozone chemistry can additionally impact the indoor air pollution.

Highly sensitive MS/MS detection for confident identification of potent novel synthetic opioids and their metabolites

The aim of this presentation is to demonstrate the use of high-resolution mass spectrometry as a unique tool for the untargeted detection and identification of new emerging substances, with little or no method optimization necessary. The presentation will demonstrate how accurate mass instruments are providing extra levels of confidence in analyte identification by reliably obtaining comprehensive MS/MS spectral fragment information that can be used for identification, confirmation, and/or library matching of potent drugs and metabolites present in discarded authentic case samples. NSO compounds were extracted from human whole blood using a liquid-liquid extraction (LLE) procedure. HPLC separation was performed on an ExionLC system using a Phenomenex Kinetex C18 column Mobile phases were ammonium formate and formic acid in methanol and acetonitrile. The flow rate was 0.4 mL/min with a total LC runtime of 15.5 minutes. The injection volume was 10 μL. MS and MS/MS data were collected for each sample using Zeno IDA for optimal sensitivity on the ZenoTOF 7600 system. Data acquisition consisted of a TOF MS scan to collect accurate mass precursor ions from 100 to 700 Da, followed by a TOF MS/MS full scan ranging from 25 to 700 Da to ensure all fragments were captured for identification using a maximum of 16 candidate ions. Data was acquired using SCIEX OS software 2.1. A series of 9 calibrator solutions were prepared by spiking control human whole blood samples with the 6 targeted analytes at final concentrations ranging from 10 pg/mL to 100 ng/mL. The series of calibrator solutions were injected to evaluate the quantitative performance of the system and its ability to accurately measure low level analytes with a high level of precision and accuracy in TOF MS mode. Each calibrator was injected in triplicate. LLOQs of between 10 and 50 pg/ml were observed for all compounds analysed. Accuracies at LLOQ ranged from 86–111% and imprecision was < 15% for all compounds analysed. In addition, the use of specific technologies afforded by the new SCIEX ZenoTOF 7600 system generated an average 9x sensitivity improvement on spectral data providing significantly improved library matching. A comprehensive and highly sensitive method for the screening and identification of potent NSO in human whole blood is described. The significant gains in MS/MS sensitivity on the SCIEX ZenoTOF 7600 system yielded an improvement in confident identifications of low-level analytes through spectral library matching. The observed sensitivity gains resulted in a 9x improvement, on average, in TOF MS/MS sensitivity across the drugs positively identified in the authentic case samples analyzed. This improvement enabled confident identification of key drugs and metabolites at trace levels that were not previously achievable. The MS/MS sensitivity levels afforded by ZenoTOF 7600 system provide a means to monitor low levels of ultra-potent NSO in poly-drug intake scenarios.

Tropical peat fire emissions: 2019 field measurements in Sumatra and Borneo and synthesis with previous studies

Abstract. Peat fires in Southeast Asia are a major source of trace gases and particles to the regional-global atmosphere that influence atmospheric chemistry, climate, and air quality. During the November 2015 record-high Ocean Niño Index (ONI, 2.6) our mobile smoke sampling team made the first, or rare, field measurements of numerous trace gases, aerosol optical properties, and aerosol chemistry and mass emissions for fires burning only peat in the Indonesian province of Central Kalimantan (on the island of Borneo). The measurements used Fourier transform infrared spectroscopy (FTIR), whole air sampling (WAS), photoacoustic extinctiometers (PAX, 401 and 870 nm), and detailed off-line analyses of particulate matter (PM) collected on filters. In September–November 2019 we measured peat fire trace gas emissions again, using WAS only, under El Niño–Southern Oscillation (ENSO)-neutral conditions (ONI, 0.3) in more remote areas of Central Kalimantan and also the Indonesian provinces of Riau, Jambi, and South Sumatra, all on the island of Sumatra. The 2019 measurements significantly expanded the geographic range and climate conditions sampled. This paper presents the 2019 results and synthesizes them with the previous fieldwork to converge on more robust regional average emission factors (EFs; grams of compound per kilogram of biomass burned) for authentic peat fires. In addition, samples of peat imported from Indonesia were burned in US laboratories, and the EFs and optical properties were characterized in more detail than in the field by a larger suite of instrumentation. We use the improved knowledge of regional emissions based on the expanded field measurements to select the most representative lab data and compute a synthesized, more “chemically complete” set of EFs and aerosol optical properties for tropical peat fires. The modified combustion efficiency (MCE) values for the peat smoke sampled in 2019 were within the range of MCEs sampled in 2015, but with a lower average in 2019 (0.718±0.021, range 0.687–0.736) than 2015 (0.772±0.035, range 0.693–0.835). Averaging the new and older data together suggests an updated MCE for tropical peat fires of ∼0.76. Despite the difference in MCE, the study-average methane emission factors (EF CH4) were remarkably similar across the 2 years probing different regions: 9.42±2.51 g kg−1 in 2019 and 9.51±4.74 g kg−1 in 2015. When parsing the 2019 samples by province, the EFs for non-methane organic gases (NMOGs) were about 3 times higher in South Sumatra and Central Kalimantan than in Jambi and Riau, but the overall 2019 study average was only ∼15 % higher than the 2015 study average. South Sumatra peat fires emitted higher amounts of carbonyl and dimethyl sulfide, suggesting a volcanic or marine influence or effects of agricultural chemicals. The lab and fieldwork taken together provide EFs for 230 trace gases including CO2 (1544 g kg−1), CO (315 g kg−1), and CH4 (9.8 g kg−1). These are significant adjustments to IPCC-recommended EFs, −9 %, +50 %, and −53 %, respectively. We also report EFs for numerous NMOGs, 46 N-containing compounds, and 14 sulfur- or halogen-containing species. The use of high-resolution mass spectrometry in the lab allowed measurement of 82 % more NMOG mass than in the field. Gravimetrically measured EF PM2.5 in the field in 2015 (17.3±5.8 g kg−1) was ∼20 % lower than the average from lab studies (22.4±10.4 g kg−1), perhaps due to higher field temperatures. Taken together the lab and field data show that the single-scattering albedo (SSA) was largely independent of wavelength and MCE in the visible (∼0.998), but lower at low MCE at 401 and 405 nm with a value of 0.958 at the study-average MCE. The absorption Ångström exponent (AAE) at the average MCE was 5.7. By far the largest PM component was weakly absorbing insoluble organic carbon.

Complementarity of two approaches based on the use of high-resolution mass spectrometry for the determination of multi-class antibiotics in water. Photodegradation studies and non-target screenings

The development of analytical methodologies to monitor different antibiotic families in water and the implementation of alternatives for their efficient elimination are a great challenge. The aim of this research was to develop a method based on solid-phase extraction followed by ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry to analyse multi-class antibiotics, including macrolides, cephalosporins, fluoroquinolones, sulfonamides and diaminopyrimidines, in waters. Several parameters affecting the extraction such as the sample pH, type of sorbent and cartridge, elution volume and breakthrough volume were optimized. The method was validated in real samples, and matrix effect was assessed, demonstrating that the use of isotopically labelled surrogate compounds was mandatory to avoid standard addition calibration for each individual samples. Urban and hospital wastewater samples, as well as natural waters, were analysed, confirming the presence of 12 of the 14 target compounds at concentrations up to 3.5 µg L−1. Non-target analysis based on data-independent workflow was also performed, enabling the identification of 94 pollutants. Preliminary photodegradation experiments were also assessed, revealing the total removal of many target compounds after the first 5–10 min of UVC irradiation. In addition, 20 by-products formed after photolysis could be identified using a non-target approach.

Use of high-resolution mass spectrometry for the first-time identification of gerberin as a tentative marker of the fraudulent organic production of tomatoes

Solanum lycopersicum cv. Ramyle was cultivated using different amounts of synthetic and natural crop protection agents, combined with organic and chemical fertilisers. Chemometric studies on the LC-Q-Orbitrap metabolite profiles of tomatoes distinguished a compound [M+H]+ at m/z 291.1075 (C12H19O8+, 0.0 ppm). The compound, identified as gerberin, is a possible marker to distinguish between organic and conventional cultivation. To our knowledge, this is the first time gerberin has been identified in tomato. A combination of HRMS, in silico, and chemical experiments, allowed the structure elucidation. Target MS2 experiments of the 291.1075 peak showed a clear breakdown to a base peak at m/z 129.0546 Da, consistent with the gerberin aglycone proton adduct (C6H9O3). Acid hydrolysis of the extract showed the disappearance of all gerberin adducts remaining the 129.0546 ion only, which matched with a commercial standard of gerberin aglycone. The levels of gerberin in the samples correlated negatively with the presence of synthetic chemicals. Gerberin content variation correlated to the application of synthetic fertilisers (T1, T2, T3, and T4, from lowest to greatest application). δ15N IRMS measurements were insufficient to discern between agricultural practices, demonstrating that fraud in organic produce using synthetic fertilisers is possible if discrimination is based on IRMS only.

Development and Validation of a Rapid Method for Identification of New Synthetic Cannabinoids in Hair Based on High-Performance Liquid Chromatography-Ion Trap Mass Spectrometry Using a Simplified User Interface.

The penetration of the new psychoactive substances (NPSs) into the market of clandestine drugs is highly dynamic, causing potentially false-negative results using the current analytical instrumentation, particularly in the screening phase. At present, the suggested approach to perform a comprehensive screening requires the use of high-resolution mass spectrometry (MS) with associated high costs of purchase and maintenance and need of skilled and dedicated personnel. Here we describe the development and validation of a simplified approach based on a high-performance liquid chromatography-ion trap MS system with a user-friendly interface dedicated to toxicological analysis. The system, originally intended for a broad toxicological screening, was tuned to identify new synthetic cannabinoids in hair. After a washing step with dichloromethane, hair (about 50 mg) was incubated for 3 h with 1.5 mL ethanol. One milliliter of this solution was then dried, reconstituted with mobile phase and injected. The peak identification was based on the chromatographic retention times and MS2/MS3 data using a database which included up to 158 NPSs. The method was validated according to international guidelines on a selected panel of NPSs, namely methyl 2-[[1-(5-fluoropentyl)indazole-3-carbonyl]amino]-3,3-dimethylbutanoate (5F-ADB), 1-Pentyfluoro-1H-indole-3-carboxylic acid 8-quinolinyl ester (5F-PB 22), N-[(2S)-1-amino-3-methyl-1-oxobutan-2-yl]-1-(5-chloropentyl)indazole-3-carboxamide (5Cl-AB-PINACA), (S)-N-(1-amino-1-oxo-3-phenylpropan-2-yl)-1-(5-fluoropentyl)-1H-indole-3-carboxamide [5F-APP-PICA (PX-1)],: (R)-N-(1-amino-1-oxo-3-phenylpropan-2-yl)-1-(5-fluoropentyl)-1H-indazole-3-carboxamide [5F-APP-PINACA (PX-2)], N-[(2S)-1-Amino-3-methyl-1-oxobutan-2-yl]-1-(cyclohexylmethyl)indazole-3-carboxamide (AB-CHMINACA), N-[(2S)-1-Amino-3-methyl-1-oxobutan-2-yl]-1-[(4-fluorophenyl)methyl] indazole-3-carboxamid (AB-FUBINACA), methyl (2S)-2-[[1-(cyclohexylmethyl)indole-3-carbonyl]amino]-3,3-dimethylbutanoate (MDMB-CHMICA), (S)-Methyl 2-(1-(5-fluoropentyl)-1H-indole-3-carboxamido)-3-methylbutanoate (MMB-2201) and (1-pentylindol-3-yl)-(2,2,3,3-tetramethylcyclopropyl)methanone (UR-144). The tested analytical method showed detection limits between 0.065 and 0.125ng/mg. The intraday imprecision of the method showed average values within the range of 7.3-20%. The estimation of the trueness (bias) of method showed average values within the range of 1.5-12.3%. The analytical performance was also successfully assessed by four proficiency test samples containing NPS. No synthetic cannabinoids were detected in application to 82 hair samples from forensic cases previously analyzed with liquid chromatography-MS triple quadrupole.

Liquid Chromatography High-Resolution Mass Spectrometry in Forensic Toxicology: What are the Specifics of Method Development, Validation and Quality Assurance for Comprehensive Screening Approaches?

The use of high-resolution mass spectrometry (HRMS) has increased over the past decade in clinical and forensic toxicology, especially for comprehensive screening approaches. Despite this, few guidelines in this field have specifically addressed HRMS issues concerning compound identification, validation, measurement uncertainty and quality assurance. To fully implement this technique, certainly in an era in which the quality demands for laboratories are ever-increasing due to various norms (e.g. the International Organization for Standardization's ISO 17025), these specific issues need to be addressed. This manuscript reviews 26 HRMSbased methods for qualitative systematic toxicological analysis (STA) published between 2011 and 2021. Key analytical data such as samples matrices, analytical platforms, numbers of analytes and employed mass spectral reference databases/libraries as well as the studied validation parameters are summarized and discussed. The article further includes a critical review of targeted and untargeted data acquisition approaches, available HRMS reference databases and libraries as well as current guidelines for HRMS data interpretation with a particular focus on identification criteria. Moreover, it provides an overview on current recommendations for the validation and determination of measurement uncertainty of qualitative methods. Finally, the article aims to put forward suggestions for method development, compound identification, validation experiments to be performed, and adequate determination of measurement uncertainty for this type of wide-range qualitative HRMSbased methods.

Identifying active xenobiotics in humans by use of a suspect screening technique coupled with lipidomic analysis.

Lipidomic analysis has been proven to be a powerful technique to explore the underlying associations between xenobiotics and health status of organisms. Here, we established a strategy that combined the lipidomic analysis with high-throughput suspect contaminant screening technique with an aim to efficiently identify active xenobiotics in humans. Firstly, in the light of single liquid phase equilibrium of chloroform-methanol-water (15:14:2, v/v/v), we developed an efficient method that was able to simultaneously extract both polar and nonpolar lipids in serum samples. By use of this method, targeted and non-targeted lipid analyses were conducted for n=120 serum samples collected from Wuxi city, China. Secondly, we established a suspect database containing 1450 contaminants that have been previously reported in human samples, and contaminants in this database were screened in the same batch of serum samples by use of high-resolution mass spectrometry (HR-MS). Thirdly, the underlying associations between suspect contaminants and lipids were explored and discussed, and we observed that levels of some lipids were statistically correlated with concentrations of numerous contaminants. Among these active contaminants, 23 ones were identified on the basis of HR MS1 and MS2 characteristics, and these contaminants belonged to the classes of phthalates, phenols, parabens, or perfluorinated compounds (PFCs). Three active xenobiotics were fully validated by comparison with authentic standards, and they were perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and diethyl phthalate (DEP). There were statistically significant changes in levels of triglyceride (TG), lysophosphocholine (LPC), and sphingomyelin (SM) as peak areas of xenobiotics increase. We also observed that, among target lipid molecules, 18:0 lysophosphatidylethanolamine (LPE(18:0)) was very sensitive, and this lipid responded to exposure of various contaminants. Our present study provides novel knowledge on potential alteration of lipid metabolism in humans following exposure to xenobiotics, and provides an efficient strategy for efficiently identifying active xenobiotics in humans.

Systematic Review of Recent Lipidomics Approaches Toward Inflammatory Bowel Disease.

Researchers have endeavored to identify the etiology of inflammatory bowel diseases, including Crohn’s disease and ulcerative colitis. Though the pathogenesis of inflammatory bowel diseases remains unknown, dysregulation of the immune system in the host gastrointestinal tract is believed to be the major causative factor. Omics is a powerful methodological tool that can reveal biochemical information stored in clinical samples. Lipidomics is a subset of omics that explores the lipid classes associated with inflammation. One objective of the present systematic review was to facilitate the identification of biochemical targets for use in future lipidomic studies on inflammatory bowel diseases. The use of high-resolution mass spectrometry to observe alterations in global lipidomics might help elucidate the immunoregulatory mechanisms involved in inflammatory bowel diseases and discover novel biomarkers for them. Assessment of the characteristics of previous clinical trials on inflammatory bowel diseases could help researchers design and establish patient selection and analytical method criteria for future studies on these conditions. In this study, we curated literature exclusively from four databases and extracted lipidomics-related data from literature, considering criteria. This paper suggests that the lipidomics approach toward research in inflammatory bowel diseases can clarify their pathogenesis and identify clinically valuable biomarkers to predict and monitor their progression.

Lipid Peroxide-Derived Short-Chain Aldehydes are Involved in Aluminum Toxicity of Wheat (Triticum aestivum) Roots.

Lipid peroxidation is a common event during aluminum (Al) toxicity in plants, and it generates an array of aldehyde fragments. The present study investigated and compared the profile and physiological functions of lipid peroxide-derived aldehydes under Al stress in two wheat genotypes that differed in Al resistance. Under Al stress, the sensitive genotype Yangmai-5 suffered more severe plasma membrane damage and accumulated higher levels of aldehydes in roots than the Al-tolerant genotype Jian-864. The complementary use of high-resolution mass spectrometry and standard compounds allowed the identification and quantification of 13 kinds of short-chain aldehydes sourced from lipids in wheat roots. Among these aldehydes, acetaldehyde, isovaldehyde, valeraldehyde, (E)-2-hexenal (HE), heptaldehyde, and nonyl aldehyde were the predominant species. Moreover, it was found that HE in the sensitive genotype was over 2.63 times higher than that in the tolerant genotype after Al treatment. Elimination of aldehydes using carnosine rescued root growth inhibition by 19.59 and 11.63% in Jian-864 and Yangmai-5, respectively, and alleviated Al-induced membrane damage and protein oxidation. Exogenous aldehyde application further inhibited root elongation and exacerbated oxidative injury. The tolerant genotype Jian-864 showed elevated aldehyde detoxifying enzyme activity and transcript levels. These results suggest that lipid peroxide-derived short-chain aldehydes are involved in Al toxicity, and a higher aldehyde-detoxifying capacity may be responsible for Al tolerance.

Verification of Exposure to Novichok Nerve Agents Utilizing a Semitargeted Human Butyrylcholinesterase Nonapeptide Assay

Novichok (NV) nerve agents were recently added to the list of Schedule 1 chemicals of the Chemical Weapons Convention. There is a well-accepted method for assessment of nerve agent exposure based on mass spectrometric analysis of a nonapeptide with the serine-198 residue modified by the nerve agent, but this approach has not yet been reported for the class of NV agents and requires the availability of reference standards, which may be a limitation for NV agent exposure assessment. Thus, a goal of this study was to first verify the utility of the nonapeptide method for the characterization of human plasma samples exposed in vitro to the NV agents A-230, A-232, and A-234. A second aim was to evaluate the possibility of identifying unknown exposures by applying precursor ion scanning in combination with high resolution mass spectrometry (HRMS). Thus, precursor ion scanning, with a generic fragment ion (m/z 778) of the nonapeptide, was used to pinpoint any modified nonapeptide, while HRMS was used for structural elucidation of the adduct moiety. By this approach, use of HRMS enabled differentiation between adducts of agents with similar molecular masses. A new unique feature that could be exploited for NV nonapeptide analysis was that the modification was released from the peptide during fragmentation in the mass spectrometer and was detected in the low-mass region of the mass spectrum. This low-mass region was extremely informative and contributed to the assignment of the structure of the particular agent used, which is especially important in case no reference materials are available. The presented method is important for verification purposes by the Organisation for Prohibition of Chemical Weapons (OPCW), e.g., in case of investigations of alleged use of NV agents, and for regular forensic investigations.

Development and Application of a Novel Semi-quantification Approach in LC-QToF-MS Analysis of Natural Products.

Use of high-resolution mass spectrometry (HRMS) including a MS calibration method has enabled simultaneous identification and quantification of knowns/unknowns. This has expanded our knowledge about the existing sample relevant chemical space in a way beyond reconciliation with a quantification task. This is largely due to fact that reference standards are not always available to achieve quantitative analysis. In this scenario, a semi-quantitative approach can fill the gap and provide a rough estimation of concentration. This research aimed to develop and compare several semi-quantification approaches based on chemical similarity or properties. The ionization efficiency scale was created for several groups of natural products. Advanced modeling approach based on a support vector machine was conducted to learn from the experimental ionization efficiency and apply it to unknowns or suspected compounds to predict their ionization efficiency in electrospray ionization mode. The developed semi-quantification workflows could be useful in most HRMS based "omics" areas, especially in natural products discovery.

Bio-activation of simeprevir in liver microsomes and characterization of its glutathione conjugates by liquid chromatography coupled to ultrahigh-resolution quadrupole time-of-flight mass spectrometry

Liquid chromatography coupled to a triple quadrupole and, alternatively, to an ultrahigh-resolution quadrupole time-of-flight (UHR-QqTOF) mass spectrometers was used to collect qualitative and quantitative information from incubations of the anti-hepatitis C drug simeprevir with human and rat liver microsomes, respectively, supplemented with NADPH and glutathione. For this, different chromatographic methods using two different chromatographic columns, Kinetex® 2.6 µm C18 (50 × 3 mm) and Atlantis T3 (100 Å, 3 µm, 4.6 mm × 150 mm), have been employed. For determination and structural characterization of the reactive metabolites, we used information obtained from high-resolution mass spectrometry, namely accurate mass data to calculate the elemental composition, accurate MS/MS fragmentation patterns for confirmation of structural proposals, and the high mass spectral resolution to eliminate false-positive peaks. In this study, the use of high-resolution mass spectrometry (HR-MS) enabled the identification of 19 simeprevir metabolites generated by O- respectively N-demethylation, oxidation, dehydrogenation, hydrolysis, and formation of glutathione conjugates. The in silico study provides insights into the sites of simeprevir most amenable to reactions involving cytochrome P450. The developed methods have been successfully applied to analyze simeprevir and its metabolites simultaneously; based on this data, potential metabolic pathways of simeprevir are discussed. In general, the obtained results demonstrate that simeprevir is susceptible to form reactive simeprevir-glutathione adducts and cyclopropansulfonamide, which may explain the implication of simeprevir in idiosyncratic adverse drug reactions (IADRs) or hepatotoxicity.

Improving the simultaneous target and non-target analysis LC-amenable pesticide residues using high speed Orbitrap mass spectrometry with combined multiple acquisition modes

The use of high-resolution mass spectrometry (HRMS) for the simultaneous target and non-target analysis of pesticide residues in food control is a subject that has been studied over the last decade. However, proving its efficacy compared to the more established triple quadrupole mass spectrometers (QQQ-MS2) is challenging. Various HRMS platforms have been evaluated, seemingly showing this approach not to be as effective as QQQ-MS2 for quantitative analysis, especially in routine food testing laboratories. The two main reasons are (i) the lower sensitivity especially in the case of the fragment ions produced and (ii) the lack of familiarity and an understanding of the most appropriate combination of HRMS acquisition modes to use. In fact, the number of different acquisition modes can appear as a puzzle to inexperienced users. This work was therefore focused on obtaining experimental data to gain a better understanding of the extended acquisition capabilities of a new Q-Orbitrap platform. Experimental data were obtained for 244 pesticides and their degradation products in commodities of varying matrix complexity (tomato, onion, avocado, and orange) using various combinations of acquisition modes. The best results for targeted analysis were obtained with a combination of full scan (FS), all-ions fragmentation (AIF) and target MS2 (tMS2) modes, and for non-target analysis using full scan (FS) and data-dependent MS2 (ddMS2) modes. All these acquisition modes (FS, AIF, tMS2, and ddMS2) could be applied simultaneously with cycle times ≤ 1 s. The tMS2 especially, proved to be a very powerful approach to increase sensitivity for MS2 fragments and identification rates. Overall, the results for the various pesticide-commodity combinations were fully satisfactory in terms of limit of quantitation (LOQ) repeatability and identification when considered against the SANTE EU Guideline criteria. In addition, the screening capabilities were evaluated for a non-target survey with the use of spectral libraries, the presence of non-target compounds was detected, thus proving the efficacy of the proposed approach. Another issue often overlooked is the optimization of use of spectral libraries, but in our experiments the compounds present in these libraries were not blindly sought in the screening analyses. To minimize the potential for false positives detects in our study, the extractability of the compounds present in the libraries, was also taken into account. The extractability of compounds using a QuEChERS acetonitrile procedure was estimated based on the physicochemical properties of target compounds. By removing compounds that will not be extracted, reduces the occurrences of false detects, reducing the time required for data processing and thus improving the efficiency of the overall screening workflow.

Determination of dextromethorphan and dextrorphan solar photo-transformation products by LC/Q-TOF-MS: Laboratory scale experiments and real water samples analysis

This work discusses the identification of the transformation products (TPs) generated during the photolytic degradation of dextromethorphan (DXM) and its metabolite dextrorphan (DXO), under simulated solar radiation in aqueous solutions (Milli-Q water and river water) in order to determinate its behavior into the aquatic environment. Tentative identification of the TPs was performed by liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QTOF-MS), following a suspect screening approach. The use of high resolution-mass spectrometry (HRMS) allowed the tentative identification of DXM and DXO photoproducts based on the structure proposed by an in silico software, the accurate mass measurement, the MS/MS fragmentation pattern and the molecular formula finding. A total of 19 TPs were found to match some of the accurate masses included in a suspect list, and they were all tentatively identified by their characteristic MS-MS fragments. Most of the TPs identified showed a minor modified molecular structure like the introduction of hydroxyl groups, or demethylation. The time-evolution of precursors and TPs were monitored throughout the experiments, and degradation kinetics were presented for each analyte. Finally, the occurrence of DXM, DXO, and their tentatively proposed photodegradation TPs was evaluated in both surface and wastewater. In all real matrices, the results showed that the highest concentration was detected for DXO, followed by TP-244 (N-desmethyldextrorphan) and DXM.

Identification of Unique 4-Methylmethcathinone (4-MMC) Degradation Markers in Putrefied Matrices†.

Drug degradation as a consequence of putrefactive bacterial activity is a well-known factor that affects the identification and quantitation of certain substances of forensic interest. Current knowledge on putrefaction-mediated degradation of drugs is, however, significantly lacking. This study aimed to investigate the degradation of 4-methylmethcathinone (4-MMC or mephedrone) and to detect its degradation products in putrefied biological matrices containing 4-MMC. The bacteria species Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris were grown in brain-heart infusion broth, spiked with 4-MMC and incubated at 37°C for 24h. Postmortem human blood and fresh porcine liver macerate were also left to putrefy in sample tubes at room temperature for 1week. Structural elucidation was based on modern spectroscopic analyses including the use of high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. All four putrefactive bacteria were capable of degrading 4-MMC extensively under the experimental conditions explored. Of particular interest was the discovery of a novel degradation product common to all four bacterial species, which was assigned as 2-hydroxy-1-(4-methylphenyl)propan-1-one (HMP) based on the spectroscopic data. This degradation product was detectable in both postmortem human blood and porcine liver samples. The stability of the identified degradation products, especially HMP, should be further investigated to assess their validity of serving as marker analytes for monitoring 4-MMC in postmortem toxicology.