Search Results (95)

Oil spills in inland rivers pose a significant threat to the surrounding environment, and the emergency response differs greatly from that in ocean or coastal areas. In this study, we focused on several commonly used emergency water treatment strategies in China’s inland oil spills, as well as the spilled washing oil in a serious accident case. We investigated the changes in oil-related chemical components before and after water treatment using GCxGC-TOF MS (Comprehensive Two-dimensional Gas Chromatography Time of Flight Mass Spectrometer). We tracked the shifts of microbial communities in the microcosms incubated with clean river water, simulated oil-contaminated water, and the treatment effluent. The results revealed that typical components, especially nitrogen-containing heterocyclic compounds, had different removal efficiencies among treatments. The diversity, composition, and potential functions of microbial communities responded differently to the treatments, and could be related to various substances, including PAHs (polycyclic aromatic hydrocarbons) and heterocyclic compounds. A few genera, such as SC-I-84, exhibited a high correlation with washing oil-related components and could serve as an indicator in such an oil spill emergency response. Our findings indicated that simply using petroleum oil or PAHs to evaluate oil spills was likely to underestimate the ecological impact, especially when the spilled substances were coal chemical products widely used in China. This will provide an important scientific basis for decision-making and strategy evaluation in emergency responses to inland oil spills. Full article

China is the place of origin and main producer of black tea worldwide, with Dianhong (DH), Chuanhong (CH), and Keemunhong (KH) being the famous Chinese black teas. The contents of various odor components in black teas differ with their origins. However, the effects of these differences on the presentation of distinctive odor characteristics in various products remain unclear. We aimed to elucidate the odor characteristics and odor compounds of these three black teas; to this end, we performed a sensory evaluation and multivariate statistical analysis based on comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC-MS) results. The sensory evaluation revealed that the odor characteristics of DH were floral and fruity, whereas sweet and herbal-like odors were more intense in CH and QH. A total of 119 volatile compounds were detected, with alcohols, aldehydes, and esters being the main volatile compounds. Among them, 41 volatile compounds were identified with an odor activity value (OAV) of >1, and 24 of them were selected through principal component analysis, hierarchical cluster analysis, and orthogonal partial least squares discriminant analysis as marker substances to distinguish the three teas; thus, 24 volatile compounds are important odor compounds of DH, CH, and QH. Full article

The most efficient technique for resolving the issue of plastic waste disposal is by converting the wastes into high-quality liquid oils through thermal and catalytic pyrolysis. The objective of this work was to study the composition of liquid oils obtained by thermal and catalytic degradation of plastic wastes containing polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). The clay catalysts were characterized by N₂ adsorption–desorption isotherms (BET), Scanning Electron Microscopy (SEM) and Fourier transform Infrared Spectrometry (FTIR), Polarized Optical Microscopy (POM), Atomic Force Microscopy (AFM). The effect of temperature and clay catalyst type on the yields of the end-products resulting in thermo-catalytic degradation of PS has been evaluated. Degradation of PS showed the highest liquid oil production at 86.85% in comparison to other plastic types. The characterization of the liquid oils was performed by comprehensive two-dimensional gas chromatography coupled with single quadrupole mass spectrometry (GC × GC-qMS). In liquid oils of PS, eighteen principal compounds (of groups: linear hydrocarbons, mono-aromatics, and di-aromatics) were identified. In the liquid oils of the plastic waste mixture, twenty-four principal compounds (of groups: linear hydrocarbons, mono-aromatics, oxygen-containing aromatic, di-aromatics, and tri-aromatics) were identified. The liquid oils were investigated in order to reconvert them as styrene monomers or other chemicals in energy recovery. Full article

This publication reports the controlled cultivation of Zanthoxylum chiloperone var. angustifolium Engl. (Rutaceae) in several growth substrates under controlled greenhouse conditions. This plant is well-known for its anti-Chagas (trypanocidal) activity, related to the presence of several β-carboline alkaloids. The metabolomic study of Z. chiloperone seedlings over two years of growth (2018–2020) was performed using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS). The canthin-6-one alkaloids, canthin-6-one and 5-methoxy-canthin-6-one, were putatively identified in Z. chiloperone extracts. Finally, in vitro and in silico studies of trypanocidal activity were performed, suggesting that canthin-6-one alkaloids could interact with the main pharmacological targets against Trypanosoma cruzi, cruzain protease, dihydroorotate dehydrogenase, lanosterol 14-alpha-demethylase, farnesyl diphosphate, and squalene synthases. Full article

As an important crop in the world, dried pepper is widely used in various foods. However, the sensory quality, fruit shape index, edible index, nutrition index, and volatile components of dried pepper have not been comprehensively analyzed. This study elucidated the differences between different varieties of dried pepper and provided the basis for the selection of raw materials for different varieties of dried pepper products. The varieties with high scores in sensory evaluation were Henan new generation, Neihuang new generation, Chengdu Erjingtiao, India S17, and Honglong 12. The varieties with the highest fruit shape index, edible rate, and nutrition index were Chengdu Erjingtiao and Guizhou Erjingtiao. A total of 380 volatile organic compounds were identified by comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry with headspace sampling (HS-GC-TOF MS), including 62 alcohols, 50 aldehydes, 68 ketones, 60 hydrocarbons, 99 esters, 18 acids, and 23 other substances such as pyrazoles and ethers. Full article

A comprehensive understanding of the compositions and physicochemical properties of coal-based liquids is conducive to the rapid development of multipurpose, high-performance, and high-value functional chemicals. However, because of their complex compositions, coal-based liquids generate two-dimensional gas chromatography (GC × GC) chromatograms that are very complex and very time consuming to analyze. Therefore, the development of a method for accurately and rapidly analyzing chromatograms is crucial for understanding the chemical compositions and structures of coal-based liquids, such as direct coal liquefaction (DCL) oils and coal tar. In this study, DCL oils were distilled and qualitatively analyzed using GC × GC chromatograms. A deep-learning (DL) model was used to identify spectral features in GC × GC chromatograms and predominantly categorize the corresponding DCL oils as aliphatic alkanes, cycloalkanes, mono-, bi-, tri-, and tetracyclic aromatics. Regional labels associated with areas in the GC × GC chromatograms were fed into the mask-region-based convolutional neural network’s (Mask R-CNN’s) algorithm. The Mask R-CNN accurately and rapidly segmented the GC × GC chromatograms into regions representing different compounds, thereby automatically qualitatively classifying the compounds according to their spots in the chromatograms. Results show that the Mask R-CNN model’s accuracy, precision, recall, F1 value, and Intersection over Union (IoU) value were 93.71%, 96.99%, 96.27%, 0.95, and 0.93, respectively. DL is effective for visually comparing GC × GC chromatograms to analyze the compositions of chemical mixtures, accelerating GC × GC chromatogram interpretation and compound characterization and facilitating comparisons of the chemical compositions of multiple coal-based liquids produced in the coal and petroleum industry. Applying DL to analyze chromatograms improves analysis efficiency and provides a new method for analyzing GC × GC chromatograms, which is important for fast and accurate analysis. Full article

Since the 1950s, the screening of the body volatilome has proven to be a powerful tool for preventing diseases from spreading. Following the COVID-19 crisis, several studies began investigating the connection between viruses and the body volatilome, gradually identifying potential biomarkers, which varied depending on the study. To try to elucidate potential sources of inconsistency in biomarker findings, we decided to set up a study taking into consideration the factors often overlooked in previous studies. The VOCs constituting the body volatilomes of 40 COVID-19 patients and 13 healthy subjects were sampled by using PowerSorb^® as the sorbent phase. Thermodesorption, followed by comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (TD-GC×GC/TOF MS), was utilized for the analysis. A non-targeted biomarker research methodology compared Covid(+) and Covid(−) chromatograms, assessing statistical significance and peak area changes. Out of the 25 compounds highlighted, 13 associated with cosmetic products were excluded, and 8 linked to air pollution in urban settings were also excluded. Finally, after having quantitatively evaluated the potential sources of the compounds (cosmetic or environmental), 4 compounds remained and their relevance was assessed using ROC curves. Among them, hexanoic acid, 2-ethyl- identification was confirmed with standard and led to an area-under-the-curve value of 92%. More in-depth studies are needed to investigate the specificity of the biomarker in relation to COVID-19, but the strategy of this study shows how to avoid obtaining data that are biased by exogenous factors. Full article

Background/Objectives: This study evaluates the applicability of a comprehensive two-dimensional gas chromatography−flame ionisation detection (GC×GC−FID) approach for the simultaneous determination of 12 underivatised psychoactive drugs, including new psychoactive substances, that comprised of amphetamine, methamphetamine, mephedrone, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, α-pyrrolidinovalerophenone, n-ethylpentylone (ephylone), norketamine, ketamine, 3,4-methylenedioxypyrovalerone, methadone, and cocaine. Methods: Separation was effected using a non-polar first dimension (¹D) and a polar second dimension (²D) column, demonstrating an improved separation of drug compounds compared to a polar/non-polar column configuration. Interference-free baseline separation of all psychoactive compounds in a urine matrix was achieved within 8 min. The GC×GC−FID method was validated according to the guidelines defined by Standard Practices for Method Validation in Forensic Toxicology. Results: The calibration curves for the 12 psychoactive drugs were well correlated (r² > 0.99) within the concentration ranges of 50–1500 ng mL⁻¹. Detection limits of 10–20 ng mL⁻¹ were obtained, and good repeatability and reproducibility (CV < 11.4%) were attained for retention times and peak areas. Method recoveries for the small-scale solvent extraction procedure ranged from 96.9 to 114.5%, and bias was between −3.1% and 14.5%. Conclusions: The validated approach was successfully applied for the determination of these illicit compounds in spiked urine samples of different concentrations, highlighting its potential for rapid forensic drug screening. Full article

Background: Plants constantly produce primary and secondary metabolites, and a significant fraction of these are volatile organic compounds (VOCs). Factors including the life stage of the plant, temperature, environment, and stress influence the abundance and types of VOCs emitted. The analysis of VOCs released by plants during different stages or with different conditions provides insight into plant metabolism and stress responses. Collecting the VOC profiles of plants in vivo makes it possible to obtain a representative sample of the entire plant volatilome under controlled conditions with minimal invasiveness. In addition, in vivo sampling can also be used to compare the impacts of different environmental conditions or stressors on plants, i.e., the presence/absence of a pest or amount of nitrogen in soil. Methods: In this study, an in vivo plant sampling technique is introduced and validated using active sampling and thermal desorption (TD) tubes with comprehensive two-dimensional gas chromatography coupled to a time-of-flight mass spectrometer (TD-GC×GC-TOFMS). The purpose of this work is to highlight a novel technique to analyze headspace secondary plant metabolites with a minimal invasiveness. Results: It was concluded that in vivo active sampling onto TD tubes provides a wider global coverage of compounds and larger peak areas when compared to extraction by solid-phase microextraction (SPME). Additionally, the Horwitz ratio of active sampling onto TD tubes was 0.893, demonstrating this technique to be a reliable and reproducible method. Lastly, a variety of plants were sampled to assess the versatility of this technique across various plant species with different sizes and volatile profiles. Hundreds of compounds were measured with this analysis, including terpenes, aldehydes, ketones, terpenoids, and alcohols. Conclusions: This novel in vivo active sampling method provides an additional technique for extracting and analyzing volatile secondary plant metabolites. Full article

The essential oil components of traditional Chinese medicine in-hospital preparation were complex, and one-dimensional chromatographic separation was difficult to completely separate them due to the limited peak capacity. This study was carried out to establish a comprehensive two-dimensional chromatographic separation and analysis method based on countercurrent chromatography (CCC) and gas chromatography (GC). In this paper, we focused on the separation of the essential oil of the traditional Chinese medicine in-hospital preparation Wenjing Tongluo San by CCC × GC, and explored the orthogonality between the two chromatographic techniques to provide the new technical support for the screening of the active ingredients. A solvent system composed of n-hexane-ethyl acetate-methanol-water (9.5:0.5:8.5:1.5, v/v) was chosen for the first-dimensional CCC separation. All the fractions collected from CCC were transferred to GC for plotting two-dimensional contours map. The calculated capacity of the two-dimensional separation system exceeded 3000, which was 8 times more than that of the one-dimensional separation system. High orthogonality (r = 0.42) and spatial coverage factor (70.42%) were obtained. Meanwhile, all the fractions were identified by GC-MS. Our research provided a new methodology for separating essential oils in traditional Chinese medicine as well as an approach for evaluating the quality of traditional Chinese medicinal in-hospital preparation based on two-dimensional chromatographic fingerprints. Full article

Stool is a mixture of excrement, microbiota, enzymes, undigested material, and small molecules. Fecal metabolomics has gained interest recently, owing to advances in metabolomics and growing research into both the host’s physiology and the gut microbiome. One challenge with fecal metabolomics is preserving the sample integrity from collection until analysis, as the microbiota and enzymes continue to alter the metabolome following defecation. Currently, flash-freezing or lyophilization are utilized to minimize post-collection metabolome changes; however, this requires complex equipment and immediate processing, precluding the possibility for at-home sampling. Commercial devices containing stabilizing solvents have been developed to facilitate at-home collection, ambient transport, and sample storage. Here, we explore the efficacy of a commercially available stool collection device with a stabilization reagent tailored to fecal metabolomics. Stool samples from six donors were either processed shortly post-collection or stored at room temperature for seven days in the tube, with and without the stabilization reagent. Comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS)-based untargeted metabolomics was utilized for analyzing extracted metabolites. Chemometric analysis was used to evaluate the performance of the device. We found that the device with the stabilization reagent minimized changes in the metabolite profile relative to unstabilized stool left at room temperature for one week. Full article

Despite the numerous benefits of intensive air transport development, many activities associated with the operation of airports contribute to environmental pollution. The purpose of this research was the development, optimization, and validation of a headspace–solid-phase microextraction–comprehensive two-dimensional gas chromatography–time of flight–mass spectrometry (HS-SPME-GC × GC-TOF-MS)-based procedure for determining anti-corrosive compounds in airport stormwater. Optimized HS-SPME conditions include: 45 min extraction time, 100 °C temperature, 1.0 g salt addition, and 10 min desorption time at 270 °C. The developed procedure is sensitive, selective, accurate (recoveries ≥ 80.0%), and precise (the coefficient of variation (CV) ≤ 14.9%), making it a highly suitable tool for extensive airport stormwater quality monitoring. The validated analytical protocol was successfully used to detect pollutants, including 1H-BT, 4-MeBT, 5-MeBT, and 5,6-diMe-1H-BT, in stormwater from various European airports with different flight capacities. Throughout the sampling period at the investigated airports, 1H-benzotriazole was found in the highest concentrations, ranging from below the MQL to 467 mg/L. An ecotoxicological risk assessment revealed that 69% of the sites exhibited high risk levels (Risk Quotient ≥ 1). The developed procedure and carried out environmental risk assessments of benzotriazoles in airport stormwater enable an evidence-based approach to sustainable airport stormwater management. Full article

Beer is a popular alcoholic beverage worldwide. However, limited research has been conducted on identifying key odor-active components in lager-type draft beers for the Chinese market. Therefore, this study aims to elucidate the odor characteristics of the four most popular draft beer brands through a sensory evaluation and an electronic nose. Subsequently, the four draft beers were analyzed through solid-phase microextraction and liquid–liquid extraction using a two-dimensional comprehensive gas chromatography–olfactometry–mass spectrometry analysis (GC×GC–O–MS). Fifty-five volatile odor compounds were detected through GC×GC–O–MS. Through an Aroma Extract Dilution Analysis, 22 key odor-active compounds with flavor dilution factors ≥ 16 were identified, with 11 compounds having odor activity values > one. An electronic nose analysis revealed significant disparities in the odor characteristics of the four samples, enabling their distinct identification. These findings help us to better understand the flavor characteristics of draft beer and the stylistic differences between different brands of products and provide a theoretical basis for objectively evaluating the quality differences between different brands of draft beer. Full article

Disinfection during tertiary municipal wastewater treatment is a necessary step to control the spread of pathogens; unfortunately, it also gives rise to numerous disinfection byproducts (DBPs), only a few of which are regulated because of the analytical challenges associated with the vast number of potential DBPs. This study utilized polydimethylsiloxane (PDMS) passive samplers, comprehensive two-dimensional gas chromatography (GC×GC) coupled with time-of-flight mass spectrometry (TOFMS), and non-negative matrix factorization (NMF) spectral deconvolution for suspect screening of DBPs in treated wastewater. PDMS samplers were deployed upstream and downstream of the chlorination unit in a municipal wastewater treatment plant located in Abu Dhabi, and their extracts were analyzed using GC×GC-TOFMS. A workflow incorporating a multi-tiered, eight-filter screening process was developed, which successfully enabled the reliable isolation of 22 candidate DBPs from thousands of peaks. The NMF spectral deconvolution improved the match factor score of unknown mass spectra to the reference mass spectra available in the NIST library by 17% and facilitated the identification of seven additional DBPs. The close match of the first-dimension retention index data and the GC×GC elution patterns of DBPs, both predicted using the Abraham solvation model, with their respective experimental counterparts—with the measured data available in the NIST WebBook and the GC×GC elution patterns being those observed for the candidate peaks—significantly enhanced the accuracy of peak assignment. Isotopic pattern analysis revealed a close correspondence for 11 DBPs with clearly visible isotopologues in reference spectra, thereby further strengthening the confidence in the peak assignment of these DBPs. Brominated analogues were prevalent among the detected DBPs, possibly due to seawater intrusion. The fate, behavior, persistence, and toxicity of tentatively identified DBPs were assessed using EPI Suite™ and the CompTox Chemicals Dashboard. This revealed their significant toxicity to aquatic organisms, including developmental, mutagenic, and endocrine-disrupting effects in certain DBPs. Some DBPs also showed activity in various CompTox bioassays, implicating them in adverse molecular pathways. Additionally, 11 DBPs demonstrated high environmental persistence and resistance to biodegradation. This combined approach offers a powerful tool for future research and environmental monitoring, enabling accurate identification and assessment of DBPs and their potential risks. Full article