Search Results (63)

Although neonicotinoids (NEOs) insecticides have been extensively detected in environmental matrices, their electron ionization (EI) fragmentation patterns have never been systematically elucidated. Because of the poor thermal stability of NEOs, gas chromatography–mass spectrometry (GC-MS) is rarely used in analysis of NEOs. This work investigated eight representative NEOs by GC-MS using multiple isotopically labeled standards, including ²H and ¹³C labeled standards to clarify fragmentation routes and establish robust structural assignment criteria. We found two main factors affecting EI fragmentation patterns. (1) The pharmacophore controlled the backbone cleavage pathway. Specifically, nitroguanidines underwent transketolation with loss of N₂O, while cyanoamidines fragment via α-cleavage. (2) The heterocycle moiety determined the diagnostic fragment ion. A heterocyclic group with chloropyridine gave the diagnostic fragment ion of m/z 126, and a chlorothiazole moiety gave the diagnostic fragment ion of m/z 132. The lack of m/z 126 and m/z 132 ions in the case of dinotefuran (DNT), which contained neither of these two moieties, indirectly suggested the rules. This set of rules effectively bridged the gap in EI mass spectral interpretation, providing a basis for ion transition selection and fragment assignment during GC-MS method development. Moreover, it could provide supportive mass-spectrometric clues for potential application in the structural elucidation of related compounds. Full article

Bamboo leaves contain structurally diverse flavonoid glycosides; whereas, compound-level information for Bambusa textilis remains limited. In this study, a flavonoid-enriched 40% ethanol fraction prepared from B. textilis leaves by petroleum-ether partitioning and AB-8 resin adsorption was analyzed by ultra-high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UHPLC-ESI-Q-TOF-MS/MS) in negative-ion mode. Retention times and MS/MS spectra were compared with seven in-house reference standards, while the remaining constituents were annotated from accurate-mass measurements, diagnostic product ions, fragmentation behavior, and data from the literature. According to Metabolomics Standards Initiative criteria, seven compounds were assigned at Level 1 and twenty-four were reported as Level 3 annotations because their exact positional structures were not confirmed by additional standards or NMR. Thirty-one flavonoid-related constituents were annotated in the analyzed fraction, encompassing six glycoside classes; most annotations, by count, were apigenin- or luteolin-derived. These annotations add compound-level information for the analyzed B. textilis fraction and allow qualitative comparison with other bamboo flavonoid profiles. Because the sample was selectively enriched, the results do not describe the complete leaf metabolome or compound concentrations. Additional standards or NMR analysis are needed to confirm the glycosylation positions of tentatively annotated compounds. Full article

Cardiac glycosides from Periplocae Cortex are bioactive constituents, but isolating and structurally confirming their trace in vivo metabolites remains challenging because authentic standards are often unavailable. We developed a steroid-core fragment-guided strategy based on the diagnostic ion at m/z 355.2270 that integrates metabolite screening, targeted purification, and structural characterization. Periplocin-related analytes were detected in rat urine and plasma after oral periplocin administration using HPLC-QQQ-MS/MS and UPLC-Q-TOF-MS/MS. Guided by the diagnostic ion, 13 L of rat urine was fractionated using macroporous resin, Sephadex LH-20, ODS chromatography, and preparative HPLC. Two trace metabolites were isolated and identified as gomphogenin (M1, 4 mg) and 17α-asclepioside (M2, 8 mg) by HR-MS and NMR spectroscopy. Periplocin, periplogenin, and periplocymarin were confirmed using reference standards. Structural comparison supported a putative transformation pathway involving deglycosylation and steroid-core modification. In a hypoxia/reoxygenation-injured H9c2 cell model, M1 and M2 increased cell viability at 50 μM, supporting further evaluation using complementary cellular endpoints. This diagnostic-ion-guided workflow enables the targeted isolation of trace cardenolide metabolites from biological matrices and provides reference compounds for future pharmacokinetic and pharmacological studies. Full article

Canolol is a pivotal phenolic antioxidant in rapeseed oil, yet its specific antioxidant mechanism and stability determinants during storage remain poorly understood. This study elucidates the antioxidant pathway of canolol within a lipid autoxidation model and evaluates its stability during the 52-week storage (25 ± 2 °C) of microwave-pretreated rapeseeds under varying packaging conditions. Rapeseeds were packaged in polyamide/polyethylene (PA/PE) vacuum bags and polypropylene (PP) atmospheric bags, and then monitored for seed quality, oil oxidative indices, and micronutrient contents. Via high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (HPLC-Q-TOF/MS/MS), a canolol-derived dimeric oxidation product (C₂₀H₂₄O₇, m/z 375.1437) was tentatively identified in an 2,2’-azobis(isobutyronitrile) (AIBN)-initiated ethyl linoleate (EtL) autoxidation system. The MS/MS fragmentation pattern—characterized by neutral H₂O loss, sequential •CH₃ eliminations, and syringyl-type diagnostic ions—supports a mechanism involving hydrogen atom transfer (HAT) from canolol to lipid-derived peroxyl radicals. This is followed by the oxidative cross-coupling of a canolol-derived phenoxyl radical (ArO•) with a hydroxyethylated intermediate (Ar′O•), confirming canolol’s role as a chain-breaking antioxidant. Correlation analyses confirmed canolol as the primary antioxidant (r = −0.914, −0.984/−0.959, −0.883 with acid value/peroxide value, p < 0.01), with a synergistic effect relationship with tocopherols (r = 0.878, 0.966, p < 0.01). PA/PE vacuum packaging (low oxygen permeability) significantly mitigated canolol degradation (22.41% loss vs. 76.34% in PP), reducing tocopherol loss and oil oxidation. This study clarifies canolol’s antioxidant pathway in rapeseed oil, providing theoretical insights for phenolic antioxidant research and practical packaging guidance for the edible oil industry. Full article

Microgreens are increasingly promoted as sustainable, nutrient-dense foods, yet their content of potentially harmful specialized metabolites remains poorly explored. Here, we developed and applied a reversed-phase liquid chromatography–electrospray ionization high-resolution mass spectrometry (RPLC-ESI-HRMS) method for the detection of cyanogenic glycosides (CNGs) in edible microgreens. Method optimization, performed using dhurrin and lotaustralin as model standards, showed that positive ion detection of sodium adducts provided the most informative and selective HRMS/MS response, with diagnostic fragmentation patterns suitable for CNG recognition in complex matrices. Quantitative validation for lotaustralin showed excellent linearity (R² = 0.998), low detection/quantification limits (LOD 0.16 mg/L; LOQ 0.53 mg/L), good extraction recovery, and a negligible matrix effect. Application of the method revealed a clear species-dependent profile. No detectable CNGs were found in broccoli raab and kale microgreens, supporting their safety as ready-to-eat products in this respect. In contrast, flax microgreens contained four CNGs: linamarin, lotaustralin, linustatin, and neolinustatin. Monoglycosylated species predominated, with lotaustralin quantified at 5.5 ± 0.6 mg/g dry weight and linamarin estimated at even higher levels. Diglycosylated CNGs were present at much lower concentrations and displayed multiple chromatographic peaks, consistent with the occurrence of structurally related isomeric forms. These quantitative results are specific to the flax microgreen samples analyzed here, obtained by pooling the lyophilized material obtained from several plants; thus, they do not account for biological variability among individual plants. Based on the measured CNG levels, flax microgreens showed a non-negligible cyanogenic potential. Assuming 1, 10 and 25% conversion to hydrogen cyanide, the estimated release would be, respectively, about 3, 33 and 81 mg HCN/kg of fresh flax microgreens, values lower than the current EU limit (150 mg HCN/kg of edible product) for flaxseed intended for direct consumption but comparable to values reported for other foods. These findings highlight the need to complement the nutritional evaluation of novel microgreens with targeted toxicological screening. Full article

Background: Radish seeds are our model on glucosinolates (GSLs), which is a class of secondary metabolites in medicinal plants of the Brassicaceae family. Multilayer perceptron (MLP) network is highly effective in the study of complex plants. This study came up with a smart plan through the Python language. Methods: First, we used the MLP network to pick out GSL precursor ions, running them through a deep learning filter. Next, we set up an automated screening system and looked at how standard chemicals break down. To speed things up, we created a scoring system that flagged promising compounds. After that, we built a tracer molecular network, basically connecting compounds according to how the plant makes them, which helped us label everything accurately. Finally, we brought in a math-based tool that pieces together different chemical parts to predict new GSL structures. Results: With this workflow, we annotated 195 glucosinolate-related compounds in radish seeds. That includes 86 regular GSLs, 34 malonyl products, 40 sinapoyl compounds, and 35 diglycosides. Among them, eight compounds were confirmed by comparison with authentic standards (retention time and MS/MS data), whereas the remaining compounds were tentatively annotated based on accurate mass measurements, diagnostic fragment ions, Tracer Molecular Nnetworking, and literature/database matching. In addition, 36 compounds were considered putatively novel derivatives pending further structural confirmation. Conclusions: This new approach reduces the time spent on determining chemicals in complicated samples. This can be done with other vegetables and medicinal herbs by researchers. It assists us in knowing the chemistry of plants in a deeper manner. Full article

Traditional Chinese prescriptions are characterized by complex chemical constituents and wide variations in constituent content, which pose a substantial challenge to their comprehensive characterization. As a classic traditional Chinese prescription known for its heat-clearing and detoxifying properties, Huangqintang Decoction (HQD) is composed of Scutellariae Radix, Paeoniae Radix Rubra, Glycyrrhizae Radix et Rhizoma, and Jujubae Fructus. In this study, we developed an off-line two-dimensional liquid chromatography that addressed the limitations of traditional analysis of unfractionated extracts, such as restricted peak capacity, which often obscured trace components. By coupling with ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS), this study successfully performed rapid identification or characterization of the complete chemical profile of HQD. Notably, beyond high-throughput identification, this approach leveraged characteristic fragment ions and reversed-phase chromatographic behaviors to differentiate some isomers of flavonoid glycosides and triterpenoid saponins, demonstrating its depth in structural identification. Flavonoid glycoside isomers were distinguished by diagnostic neutral losses, while flavanones and chalcones were characterized by retro-Diels–Alder (RDA) and β-rearrangement, respectively. Isomers of triterpenoid saponins were inferred from aglycone-specific pathways alongside RDA cleavages. Ultimately, a total of 192 compounds were identified, including 88 flavonoids, 80 triterpenoids, 7 monoterpene glycosides, 3 fatty acid amides, 3 phenylethanoid glycosides, 4 coumarins, 3 saccharides, 1 organic acid, and 3 others. This study demonstrated that the off-line two-dimensional liquid chromatography analysis strategy significantly enhanced chromatographic resolution and expanded the coverage of trace components. It presented an effective strategy for comprehensive compound identification in complex traditional Chinese medicine prescriptions. Full article

Despite their significance as forensic targets, alkyl nitrites, classified as illegal drugs, have received little attention in forensic analysis due to their high volatility and chemical instability. Here, we present a high-performance analytical approach using a pulsed dc soft plasma ionization-quadrupole mass spectrometry (pulsed dc SPI-MS) system, uniquely designed to operate using ambient air as the discharge gas. In this system, the modulation of the duty ratio functions as a “structural probe” to identify reactive isomers. Unlike conventional dielectric barrier discharge (DBD) sources that typically operate at atmospheric pressure, our SPI system utilizes a controlled pressure regime of several kPa, where the nitrogen in the ambient air effectively functions as a third-body gas to suppress excessive internal energy. The control of the duty ratio in our pulsed dc SPI source allowed for the successful manipulation of ion–molecule reaction pathways for highly reactive analytes. By optimizing several parameters, including duty ratio and discharge pressure, we achieved a unique ionization regime where the molecular-related ion [2 M − 3 H]⁺ was predominantly detected as the base peak with minimal fragmentation. Notably, by reducing the duty ratio from 50% to 5%, both the target ion occupancy and signal intensity were significantly enhanced, achieving a limit of detection (LOD) as low as 0.16 parts per million by volume (ppmv). This sensitivity is several orders of magnitude higher than previously reported thresholds, enabling rapid identification of C4–C6 alkyl nitrite isomers. This method transforms the duty ratio into a powerful diagnostic tool for identifying reactive intermediates, providing a practical and efficient approach for the onsite identification of illegal alkyl nitrites in forensic and security fields. Full article

Kavalactones are psychoactive substances that naturally occur in some plants, such as Piper methysticum, Alpinia zerumbet, and Achyrocline satureioides, which are considered to have a significantly positive effect on human organisms. For example, Alpinia zerumbet is classified as a life-expanding plant. Although high-pressure liquid chromatography–mass spectrometry has been used for kavalactone analysis in plant material, the fragmentation pathways of protonated kavalactone molecules are not fully known and require further detailed study. In this paper, the fragmentation pathways of [M+H]⁺ ions of twelve kavalactones, including three pairs of isomers, are discussed in detail. Special emphasis has been placed on diagnostic product ions, which are characteristic of kavalactone structures. It has been demonstrated that diagnostic ions and structure–fragmentation relationships enable the differentiation of isomeric kavalactones and may be useful for the identification of other kavalactone conjugates, such as kavalactone dimers or kavalactone glycosides. Full article

Mass spectrometry-based analysis of post-translational modifications (PTMs) is a key strategy for characterizing protein regulation and identifying disease-associated targets, with endogenous PTMs serving as biomarkers for disease diagnosis and therapeutic response. More recently, chemical proteomic strategies have adapted PTM-focused workflows to measure engagement of covalent and photoactivatable small-molecule probes, expanding the scope of ligand discovery for these disease-associated targets. This review provides an overview of mass spectrometry-based PTM analysis workflows, including LC–MS/MS acquisition and post-acquisition data processing, with an emphasis on how modification-specific physicochemical properties influence PTM detection and identification. Common analytical challenges that limit PTM identification, including variable MS/MS fragmentation behavior and modification site localization, are discussed using modifications such as phosphorylation and photoaffinity labeling probe adducts as representative examples. Recent advances in acquisition strategies and computational tools that improve spectral quality and confidence in PTM assignment are also summarized. Additionally, approaches for the analytical validation of modification events, such as metabolic labeling strategies, are described. Together, this review outlines key considerations, capabilities, and limitations of MS-based PTM profiling and provides a framework for interpreting PTM datasets to support their effective integration into downstream biochemical and disease target validation studies. Full article

High-resolution mass spectrometry (HRMS) enables non-targeted detection of drugs and metabolites in complex matrices. Phase II metabolites—especially glucuronides—are often the only detectable biomarkers in late or postmortem samples but are underrepresented in commercial libraries. This work pursued the prediction of phase II-glucuronide conjugates in diluted urine samples by non-targeted/targeted LC-HRMS workflows. A simply “dilute-and-shoot” qualitative UHPLC-HRMS/MS method (Q Exactive HF, ddMS²) was integrated with Compound Discoverer^® software for data processing. The workflow incorporated predictive strategies such as exact mass suspect lists, Structured Query Language (SQL)-based filters, compound-class and diagnostic neutral-loss rules (including the characteristic loss of 176.0321 Da for glucuronides) and MS/MS confirmation using both in-house and public spectral libraries. An additional part of the application’s performance assessment involved its validation for diluted urine sample. A qualitative validated method for more than two hundred drugs in urine samples was performed, including the method’s selectivity/specificity, limit of identification, matrix effects, and potential carryover. Most analytes fulfilled the qualitative acceptance criteria, with more than 60% successfully identified at a concentration of at least 2.5 ng/mL. Matrix effects were within acceptable limits for most compounds, and no severe ion suppression was observed. A non-targeted workflow was applied to real forensic samples (n = 16), allowing a reduction of approximately 66,800 detected features to 225 glucuronide candidates, while a targeted workflow based on exact mass lists yielded 31 high-confidence identifications. Characteristic neutral losses and diagnostic fragment ions led to the tentative identification of some glucuronide phase II metabolites such as mirtazapine–glucuronide, morphine-6–glucuronide, and glucuronide conjugates of benzodiazepines and synthetic opioids. In conclusion, the integration of biotransformation knowledge with HRMS-based predictive filtering allows for the efficient and hydrolysis-free detection of glucuronide metabolites, thereby extending detection windows and enhancing toxicological interpretation in complex forensic scenarios. This adaptable and library-independent workflow also facilitates retrospective data mining, making it suitable for the identification of emerging substances and newly characterized metabolites. Full article

Background: Glucose, a central carbohydrate in higher organisms’ metabolism, can undergo extensive oxidative modification under conditions of excessive inflammation or elevated reactive oxygen and nitrogen species (RONS). Such modifications yield glucose oxidation products (GOPs) with potential biological relevance and toxicity. This study aimed to systematically characterize GOP formation under defined oxidative conditions generated by gas plasma treatment. Methods: D-glucose solutions were prepared at 0.25 mM (hypoglycemic/diabetic range), 2.5 mM (sub-physiological), and 25 mM (peritoneal dialysis fluid). Samples were exposed for up to 20 min to the atmospheric-pressure argon plasma jet kINPen, which produces a wide spectrum of RONS. Treatment time-dependent glucose oxidation was assessed by high-resolution mass spectrometry (HRMS) and tandem mass spectrometry (MS/MS) to identify the oxidation products. Results: Gas plasma exposure generated various oxidation products and their abundance profiles depended on initial glucose concentration and treatment duration. Identified products included 2-keto-D-glucose, 3-deoxyglucosone (3DG), 3,4-dideoxyglucosone-3-ene (3,4DGE), furaldehyde, methylglyoxal, and acetaldehyde. HRMS/MS analysis confirmed diagnostic fragment ions for each GOP and revealed distinct formation across the model scenarios. Conclusions: Cold gas plasma induces a spectrum of glucose oxidation products under biomedically relevant glucose levels. The identified GOPs, many of which have known cytotoxic or signaling properties, provide mechanistic insight into glucose oxidation in inflamed or oxidative microenvironments. These findings support the utility of plasma-based oxidative models for studying GOP-associated biological effects and potential pathophysiological consequences. Full article

Diabetic nephropathy (DNR) remains a major complication of type 2 diabetes with limited options to halt progression. We evaluated whether DNR (a sulfur-rich extract from Hongsan garlic) confers renoprotection in a db/db mouse model. Seventy male C57BLKS/J mice were randomized into seven groups (db/m control, db/db control, metformin 250 mg/kg, DNR 100/300/900 mg/kg, and metformin 250 mg/kg + DNR 300 mg/kg) and treated orally for eight weeks. Physiological, biochemical, urinary, histological, and immunohistochemical(IHC) endpoints were assessed, including serum creatinine, blood urea nitrogen(BUN), lipids, glucose, urinary microalbumin/albumin-to-creatinine ratio(ACR), glomerular area, mesangial expansion, and renal KIM-1 and TGF-β1 expression. Chemical profiling of the DNR extract by HPLC and LC–MS/MS identified allicin as a principal sulfur-containing constituent, exhibiting a distinct retention peak at 2.90 min and a protonated molecular ion at m/z 162.1 [M]⁺ with diagnostic fragment ions at m/z 145.1, 120.1, and 99.0. Allicin was qualitatively confirmed as a characteristic component of DNR, serving as a representative chemical marker for compositional characterization. DNR produced dose-dependent improvements: reductions in serum creatinine and BUN, improved lipid and glycemic profiles, decreased urinary microalbumin and ACR, and amelioration of glomerular hypertrophy and mesangial matrix expansion. IHC showed lower KIM-1 and TGF-β1 staining in treated groups. Effects at higher DNR doses were comparable to or additive with metformin for several endpoints. These findings indicate that DNR has promising renoprotective effects in this preclinical model. Full article

Background/Objectives: Animal and fungal sterols and stanols exhibit remarkable structural diversity, driven by variations in the number and position of C=C bonds within the steroidal tetracyclic core and side chain, along with diverse branching patterns of the latter. Similarly to phytosterols, these metabolites produce highly complex tandem mass spectra, whose interpretation has so far been limited. To address this gap, the fragmentation behavior of selected animal/fungal sterols and stanols was studied in this paper. Methods: Higher-Collisional-energy Dissociation–High-resolution tandem mass spectrometry (HCD-HRMS/MS) of protonated/dehydrated species generated via atmospheric pressure chemical ionization (APCI) was performed on structurally diverse compounds, including lathosterol, desmosterol, zymosterol, lanosterol, ergosterol, chalinasterol, and the stanols coprostanol and cholestanol. Results: Structurally diagnostic product ions originating from the side chains were unveiled, shedding light on the intramolecular migration of positive charge from the initial ionization site at C3 to alternative stable sites across the molecular structure, which is a typical mechanism also noted in cholesterol and phytosterols. In addition, characteristic fragmentation patterns related to the steroidal backbone were found and discussed for Δ⁷, Δ^5,7 and Δ⁸-sterols, and a novel elucidation of the fragmentation behavior of 4,4-dimethyl-Δ⁸-sterols, based on lanosterol as a model compound, was achieved. The relative intensities of diagnostic product ions allowed a correlation with specific structural motifs, and “cholesterol-like” and “stigmasterol-like” fragmentations pathways were recognized. These findings were integrated with prior data on cholesterol and plant sterol fragmentation acquired under identical analytical conditions. Moreover, as a proof of its relevance for novel sterol identification, MS/MS-related information was successfully applied to the identification of a positional isomer (Δ⁷) of zymosterol in baker’s yeast extract, along with typical fungal major sterols. Conclusions: The comprehensive archive of sterol/stanol fragmentations obtained by APCI-HCD-MS/MS might prove very useful for the future characterization of novel sterol/stanol species in complex matrices. Full article

Electrochemical energy storage technology, primarily lithium-ion batteries, has been widely applied in large-scale energy storage systems. However, differences in assembly structures, manufacturing processes, and operating environments introduce parameter inconsistencies among cells within a pack, producing complex, high-volume datasets with redundant and fragmented charge–discharge records that hinder efficient and accurate system monitoring. To address this challenge, we propose a hybrid ASW-UKF-TRF framework for the classification and compression of battery data collected from energy storage power stations. First, an adaptive sliding-window Unscented Kalman Filter (ASW-UKF) performs online data cleaning, imputation, and smoothing to ensure temporal consistency and recover missing/corrupted samples. Second, a temporally aware TRF segments the time series and applies an importance-weighted, multi-level compression that formally prioritizes diagnostically relevant features while compressing low-information segments. The novelty of this work lies in combining deployment-oriented engineering robustness with methodological innovation: the ASW-UKF provides context-aware, online consistency restoration, while the TRF compression formalizes diagnostic value in its retention objective. This hybrid design preserves transient fault signatures that are frequently removed by conventional smoothing or generic compressors, while also bounding computational overhead to enable online deployment. Experiments on real operational station data demonstrate classification accuracy above 95% and an overall data volume reduction in more than 60%, indicating that the proposed pipeline achieves substantial gains in monitoring reliability and storage efficiency compared to standard denoising-plus-generic-compression baselines. The result is a practical, scalable workflow that bridges algorithmic advances and engineering requirements for large-scale battery energy storage monitoring. Full article