Gas Chromatography-quadrupole Mass Spectrometry Research Articles

Comparative Investigation of Aroma-Active Volatiles in ("Ruixue", "Liangzhi", "Crystal Fuji," and "Guifei") Apples by Application of Gas Chromatography-Mass Spectrometry-Olfactometry (GC-MS-O) and Two-Dimensional Gas Chromatography-Quadrupole Mass Spectrometry (GC × GC-qMS) Coupled with Sensory Molecular Science.

Aroma dramatically impacts the overall flavor profiles and consumer acceptance; therefore, it is necessary to conduct a comprehensive analysis of the aroma characteristics of apples. In this study, the aroma differences among four popular apple varieties ("Ruixue", "Liangzhi", "Crystal Fuji," and "Guifei") were compared using two extraction methods (headspace-solid phase microextraction, and solvent-assisted flavor evaporation) coupled with gas chromatography-mass spectrometry-olfactometry (GC-MS-O) and two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-qMS). A total of 82 odorants were identified via GC-MS-O, and 143 volatiles were identified by GC× GC-qMS. Among them, 41 key aroma-active compounds (butanal, ethyl acetate, 3-methylbutanal, methyl butanoate, 2-methylpropyl acetate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, butyl acetate, hexanal, 2-methylbutyl acetate, 1-butanol, 2-methylpropyl butanoate, 3-methylbutyl acetate, (E)-2-hexenal, butyl butanoate, butyl 2-methylbutanoate, hexyl acetate, hexyl butanoate, hexyl, 2-methylbutanoate, 1-octen-3-ol, 3-methylthiopropanol, 1,3-octanediol, linalyl acetate, and so on) with high odor activity values (OAVs) and AI value (odor activity values ≥1 or aroma intensity ≥3) were identified. Partial least-squares-discriminant analysis showed that Ruixue exhibited a high "fruity" note, Guifei and Crystal Fuji had the greatest "wood," "floral," and "sweet" notes, while Liangzhi presented a significant "green" note. This study provided flavor chemistry support for the apple quality control and production.

Revealing the evolution of lipid extracts from tilapia (Oreochromis mossambicus) during cold storage: Based on lipid metabolism analysis via GC-Q-MS and characterization of lipid oxidation

Lipid oxidation of tilapia is unavoidable during cold storage. Therefore, this study revealed the lipid metabolism process of tilapia using gas chromatography-quadrupole-mass spectrometry (GC-Q-MS) based lipid metabolism analysis, analyzed the free radicals, and characterized the lipid oxidation and free fatty acids (FFAs) to clarify the contribution of lipid in tilapia during cold storage. Three important metabolic pathways including biosynthesis of unsaturated fatty acids, fatty acids degradation, and fatty acids biosynthesis and differential metabolites were screened. A metabolic network map related to lipid metabolism was constructed. And from the indicators characterizing the lipid oxidation, free radicals, and the FAAs profiles displayed that the lipid was oxidized to a higher degree during cold storage. Overall, this study provided an explanation of lipid oxidation and the contribution of lipid metabolism in tilapia during cold storage, which helps in the insights on the improvement and regulation of quality.

Non-target screening and prioritization of organic contaminants in seawater desalination and their ecological risk assessment

The impact of desalination brine on the marine environment is a global concern. Regarding this, salinity is generally accepted as the major environmental factor in desalination concentrate. However, recent studies have shown that the influence of organic contaminants in brine cannot be ignored. Therefore, a non-targeted screening method based on comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-qMS) was developed for identifying organic contaminants in the desalination brine. A total of 404 compounds were tentatively identified from four seawater desalination plants (three reverse osmosis plants and one multiple effect distillation plant) in China. The identified compounds were prioritized based on their persistence, bioaccumulation, ecotoxicity, usage, and detection frequency. Twenty-one (21) compounds (seven phthalates, ten pesticides, four trihalomethanes) were then selected for further quantitative analysis and ecological risk assessment, including compounds from the priority list along with substances from the same chemical classes. Ecologically risky substances in brine include diisobutylphthalate and bis(2-Ethylhexyl) phthalate, atrazine and acetochlor, and bromoform. Most of the contaminants come from raw seawater, and no high risk contaminants introduced by the desalination process have been found except for disinfection by-products. In brine discharge management, people believed that all pollution in raw seawater was concentrated by desalination process. This study shows that not all pollutants are concentrated during the desalination process. In this study, the total concentration of pesticide in the brine increased by 58.42%. The concentration of ∑PAEs decreased by 13.65% in reverse osmosis desalination plants and increased by 10.96% in the multi-effect distillation plant. The concentration of trihalomethane increased significantly in the desalination concentrate. The change in the concentration of pollutants in the desalination concentrate was related to the pretreatment method and the chemical characteristics of the contaminants. The method and results given in this study hinted a new idea to identify and control the environmental impact factors of brine.

Development of an integrated high-voltage electron microscope-gas chromatograph-quadrupole mass spectrometer system for the operando analysis of catalytic gas reactions.

This paper describes the development of a gas chromatography-quadrupole mass spectrometry system attached to a differential-pumping-type environmental cell of the reaction science high-voltage electron microscopy instrument at Nagoya University to distinguish unambiguously between different gas species with the same mass-to-charge ratio. Several model experiments were used to verify the efficacy of the newly proposed system, confirming its ability to analyse the atomic-level structural changes during heterogeneous catalysts and the associated gas-reaction kinetics simultaneously, providing new insights into operando measurements in the field of environmental transmission electron microscopy. Graphical Abstract.

A GC×GC-MS method based on solid-state modulator for non-targeted metabolomics: Comparison with traditional GC-MS method

The formidable challenge posed by the presence of extremely high amounts of compounds and large differences in concentrations in plasma significantly complicates non-targeted metabolomics analyses. In this study, a comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC×GC-qMS) method with a solid-state modulator (SSM) for non-targeted metabolomics in beagle plasma was first established based on a GC-MS method, and the qualitative and quantitative performance of the two platforms were compared. Identification of detected compounds was accomplished utilizing NIST database match scores, retention indices (RIs) and standards. Semi-quantification involved the calculation of peak area ratios to internal standards. Metabolite identification sheets were generated for plasma samples on both analytical platforms, featuring 22 representative metabolites chosen for validating qualitative accuracy, and for conducting comparisons of linearity, accuracy, precision, and sensitivity. The outcomes revealed a threefold increase in the number of identifiable metabolites on the GC×GC-MS platform, with lower limits of quantitation (LLOQs) reduced to 0.5–0.05 times those achieved on the GC-MS platform. Accuracy in quantification for both GC×GC-MS and GC-MS fell within the range of 85–115%, and the vast majority of intra- and inter-day precisions were within the range of 20%. These findings underscore that relative to the conventional GC-MS method, the GC×GC-MS method developed in this study, combined with SSM, exhibits enhanced qualitative capabilities, heightened sensitivity, and comparable accuracy and precision, rendering it more suitable for non-targeted metabolomics analyses.

Unraveling the characteristic chestnut aroma compounds in MeiTanCuiYa green tea and their interaction mechanisms with broad-spectrum olfactory receptors using molecular docking

The important characteristics of chestnut aroma compounds in MeiTanCuiYa (MTCY) green tea were determined using gas chromatography-mass spectrometry-olfactometry (GC-MS-O), two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-qMS), chiral analysis, and partial least squares-discriminant analysis (PLS-DA). The results indicated that geraniol, (S)-(−)-furaneol, benzothiazole, 2-ethyl-3,6-dimethylpyrazine, coumarin, (R)-(−)-linalool, (E)-geranylacetone, phenylacetaldehyde, 2-pentylfuran, 2-ethyl-5-methylpyrazine, β-cyclocitral, benzyl alcohol, β-ionone, 2,5-dimethylpyrazine, furfural, etc. were closely related to the chestnut aroma. Furthermore, the molecular docking was used to analyze the region, binding energy, and force of the interaction between the chestnut aroma compounds (geraniol, (S)-(−)-furaneol, benzothiazole, 2-ethyl-3,6-dimethylpyrazine and coumarin) and ORs (OR1G1, OR1W2, OR52D1, OR5M3, OR5K1). The average binding energies of these compounds on the five receptors were −4.14 kcal/mol, −4.42 kcal/mol, −4.36 kcal/mol, −4.96 kcal/mol, and −5.79 kcal/mol, respectively. Hydrogen bonding, hydrophobic interactions and π-π stacking are important driving forces. The mechanism of formation of chestnut aroma was revealed, which provides theoretical guidance for the regulation of chestnut aroma in MTCY.

Depth-dependent variations of physicochemical properties of sedimentary dissolved organic matter and the influence on the elimination of typical pharmaceuticals

Sedimentary dissolved organic matter (DOM) could exert a significant influence on the transformation of trace organic contaminants. However, the variations of sedimentary DOM properties with depth and their impact on trace organic contaminants biodegradation remain unclear. In this study, the qualitative changes in DOM properties with depth were assessed using spectral techniques. Specifically, within the sediment range of 0–30 cm, humic acid and fulvic acid fractions exhibited higher degrees of humification and aromatization at 10–20 cm, while hydrophilic fractions showed higher degrees of humification and aromatization at 20–30 cm. Furthermore, electrochemical methods were employed to quantitatively assess the electron transfer capacity of sedimentary DOM at different depths, which displayed consistent variation trend with humification and aromatization degree. The high degree of humification and aromatization, along with strong electron-accepting capability of DOM, significantly enhanced the biodegradation rates of tetracycline and ritonavir. To gain deeper insights into the influence of molecular composition of DOM on its properties, two-dimensional gas chromatography-quadrupole mass spectrometry analysis revealed that quinones and phenolic hydroxyl compounds govern the redox reactivity of DOM. Simulated experiment of DOM-mediated biodegradation of typical pharmaceuticals confirmed the role of quinones and phenolic hydroxyl groups in the redox reactivity of DOM.

Comprehensive characterization of speciated volatile organic compounds (VOCs), gas-phase and particle-phase intermediate- and semi-volatile volatility organic compounds (I/S-VOCs) from Chinese diesel trucks

We established the comprehensive emission profiles of organic compounds for typical Chinese diesel trucks. The profiles cover the entire volatility range, including speciated volatile organic compounds (VOCs), intermediate-volatility organic compounds (IVOCs), and semi-volatile organic compounds (SVOCs). The VOCs and I/SVOCs were analyzed by one-dimensional gas chromatography quadrupole mass spectrometry (GC qMS) and two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-ToF-MS) separately. The impacts of starting mode and aftertreatment technology on the VOC, gaseous and particulate I/SVOC emissions, and the gas-particle partitioning were investigated. The emission factor (EF) of gas phase I/SVOCs was approximately 10 times higher than that of particle phase I/SVOCs and the chemical compositions and volatility distributions varied greatly. VOC, IVOC, and SVOC emissions significantly decreased when vehicles were equipped with advanced aftertreatment technologies. Diesel particulate filters (DPF) can remove >71 % VOC, 74 % gaseous, and 88 % particulate I/SVOCs, many of which are significant secondary organic aerosol (SOA) precursors. The chemical compositions and volatility distributions of the gaseous I/SVOCs and unburned diesel fuel were similar, revealing that diesel fuel is the main origin of the gaseous I/SVOCs. The I/SVOC emission profiles covering the whole volatility range, i.e., log10C* = −3 to 10 (C*: effective saturation concentration, μg m−3) were established.

Development of a method for analysis and risk assessment of residual pesticides in ginseng using liquid and gas chromatography-tandem mass spectrometry.

In this study, we developed a method for detecting 335 pesticides in ginseng using liquid chromatography quadrupole mass spectrometry (LC-MS/MS) and gas chromatography quadrupole mass spectrometry (GC-MS/MS). Additionally, the linearity, sensitivity, selectivity, accuracy, and precision of the method was validated. The limits of detection (LOD) and limits of quantification (LOQ) for the instrument used in these experiments was 0.1-5.8μg/kg and 0.3-17.5μg/kg, respectively. The average recovery was 71.6-113.4%. From 2016 to 2019, 467 ginseng samples were analyzed, of which 304 samples detected pesticide residues, but most of them were below the standard. It can be observed that the hazard quotient (HQ) of ginseng for detected pesticides wasless than1, thus implying that the risk was low. Hence, in this study, we developed a specific, reliable, and suitable method for a fast and simultaneous analysis of 335 pesticides in ginseng.

The Impact of Pigment-Epithelium-Derived Factor on MCF-7 Cell Metabolism in the Context of Glycaemic Condition.

Studies have demonstrated that pigment-epithelium-derived factor (PEDF) is a robust inhibitor of tumour growth and development, implying that this may serve as a promising target for therapeutic intervention. However, the precise impact of PEDF on cancerous cell metabolic pathways remains uncertain despite ongoing research. In this light, this study aimed to employ a metabolomics approach for understanding the metabolic reprogramming events in breast cancer across different glycaemic loads and their response to PEDF. Gas chromatography-quadrupole mass spectrometry (GC/Q-MS) analysis revealed metabolic alterations in ER+ human cell line MCF-7 cells treated with PEDF under varying glycaemic conditions. The identification of significantly altered metabolites was accomplished through MetaboAnalyst (v.5.0) and R packages, which enabled both multivariate and univariate analyses. Out of the 48 metabolites identified, 14 were chosen based on their significant alterations in MCF-7 cells under different glycaemic conditions and PEDF treatment (p < 0.05, VIP > 0.8). Dysregulation in pathways associated with amino acid metabolism, intermediates of the TCA cycle, nucleotide metabolism, and lipid metabolism were detected, and they exhibited different responses to PEDF. Our results suggest that PEDF has a diverse influence on the metabolism of MCF-7 cells in both normo- and hyperglycaemic environments, thereby warranting studies using patient samples to correlate our findings with clinical response in the future.

Unraveling the difference in flavor characteristics of Huangjiu fermented with different rice varieties using dynamic sensory evaluation and comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry.

To investigate the specific differences in flavor characteristics of Huangjiu fermented with different rice varieties, dynamic sensory evaluation, comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-qMS) and multivariate statistical analysis were employed. Dynamic sensory evaluation methods including temporal dominance of sensations (TDS) and temporal check all that apply (TCATA) were applied to explore the differences and variations in sensory attributes. The sensory results showed that the intensity of astringency and post-bitterness in the Huangjiu fermented with glutinous rice was weaker while ester and alcoholic aroma were more prominent than the one fermented with japonica rice. The results of free amino acids and aroma compounds analysis indicated that the amino acids were mainly sweet and bitter amino acids, and some key aroma compounds were predominant in the Huangjiu fermented with glutinous rice, such as ethyl butyrate (OAV: 38-59), 3-methylthiopropionaldehyde (OAV: 47-96), ethyl caprylate (OAV: 30-38), while nonanal, phenyl acetaldehyde and vanillin contributed significantly to the Huangjiu fermented with japonica rice. The multivariate statistical analysis further confirmed that 17 compounds (VIP > 1 and p < 0.05) could be supposed to be the key compouns that cause significant flavor differences in Huangjiu samples fermented with different brewing rice. Moreover, partial least-squares analysis revealed that most compounds (ethyl butyrate, 3-penten-2-one, isoamyl acetate, and so on) correlated with ester and alcoholic aroma. The results could provide basic data and theoretical basis for the selection of raw materials in Huangjiu.

866-P: Quantitative Analysis of Metformin-Induced Glucose Excretion in the Intestine

The enhancement of the uptake of 18F-labeled fluorodeoxyglucose (FDG) during [18F]FDG PET is a recently found metformin action in the gut. Taking advantage of PET-MRI, which provides better tissue registration and soft-tissue contrast than conventional PET-CT, we revealed that metformin enhanced FDG accumulation in the intestinal lumen. We now quantitatively analyzed the phenomenon with a newly developed protocol of PET-MRI. We also analyzed the intestinal glucose dynamics using 13C-labeled glucose and mass spectrometry in mice. We adopted imaging sequences of MR enterography to create 3D images of the intestinal tract, then superimposed the [18F]FDG PET images to obtain the 3D distribution of radioactivity. We conducted this test on type 2 diabetes subjects treated (N=5) or not (control, N=5) with metformin. Radioactivity was detected in the wall and lumen at similar extents in the control. However, in the metformin group, the radioactivity in the lumen, but not the wall, was three to four-fold greater than that in the control. We mathematically analyzed the data using a compartment model and calculated the glucose excretion rate (GER). GER of the control and metformin groups were 6.8 ± 1.2 mg/min and 26.1 ± 2.9 mg/min, respectively, the latter being comparable to glucose excretion into the urine induced by SGLT2 inhibitors. For mouse experiments, we intravenously injected 13C-glucose into C57/B6 mice and analyzed the feces 1 hour after injection with a gas chromatography-quadrupole mass spectrometry. We could not detect 13C-glucose in the feces, possibly because gut microbiota metabolizes glucose in the intestine. However, the content of 13C in short-chain fatty acids (SCFAs) was increased by the injection of 13C-glucose, and metformin augmented the incorporation of 13C into SCFAs. These results suggest that glucose in the circulation transfers to the intestinal lumen at a considerable rate and is metabolized by microbiota, at least partly, into SCFAs and that metformin augments the processes. Disclosure Y.Hosokawa: None. K.Sakaguchi: Research Support; Sumitomo Dainippon Pharma Co., Ltd. J.Ito: None. K.Sugawara: None. Y.Morita: None. W.Ogawa: Advisory Panel; Abbott Japan Co., Ltd., Research Support; Boehringer Ingelheim Japan, Inc., Eli Lilly Japan K.K., Novo Nordisk, Teijin Pharma Limited, Kowa Company, Ltd., Sumitomo Dainippon Pharma Co., Ltd., Abbott Japan Co., Ltd., Speaker's Bureau; Sumitomo Dainippon Pharma Co., Ltd. Funding Japan Society for the Promotion of Science (21K08578, 22K18393)

Effects of Protein Components on the Chemical Composition and Sensory Properties of Millet Huangjiu (Chinese Millet Wine).

Millet Huangjiu is a national alcoholic beverage in China. The quality of Chinese millet Huangjiu is significantly influenced by the protein components in the raw materials of millet. Therefore, in this study, the impact of different protein components on the quality of millet Huangjiu was investigated by adding exogenous proteins glutelin and albumin either individually or in combination. The study commenced with the determination of the oenological parameters of different millet Huangjiu samples, followed by the assessment of free amino acids and organic acids. In addition, the volatile profiles of millet Huangjiu were characterized by employing HS-SPME-GC/MS. Finally, a sensory evaluation was conducted to evaluate the overall aroma profiles of millet Huangjiu. The results showed that adding glutelin significantly increased the contents of total soluble solids, amino acid nitrogen, and ethanol in millet Huangjiu by 32.2%, 41.5%, and 17.7%, respectively. Furthermore, the fortification of the fermentation substrate with glutelin protein was found to significantly enhance the umami (aspartic and glutamic acids) and sweet-tasting (alanine and proline) amino acids in the final product. Gas chromatography-quadrupole mass spectrometry coupled with multivariate statistical analysis revealed distinct impacts of protein composition on the volatile organic compound (VOC) profiles of millet Huangjiu. Excessive glutelin led to an over-accumulation of alcohol aroma, while the addition of albumin protein proved to be a viable approach for enhancing the ester and fruity fragrances. Sensory analysis suggested that the proper amount of protein fortification using a Glu + Alb combination could enhance the sensory attributes of millet Huangjiu while maintaining its unique flavor characteristics. These findings suggest that reasonable adjustment of the glutelin and albumin contents in millet could effectively regulate the chemical composition and improve the sensory quality of millet Huangjiu.

Metabolomics Profiling Reveals the Role of PEDF in Triple-Negative Breast Cancer Cell MDA-MB-231 under Glycaemic Loading

Pigment epithelium-derived factor (PEDF) is a secreted glycoprotein that belongs to the serine protease inhibitor (serpin) family. An increase in PEDF activity has been shown to be a potent inhibitor of tumour progression and proliferation, suggesting a possible therapeutic target. There is still a great deal to learn about how PEDF controls metabolic pathways in breast cancer and its metastatic form. Given this, the primary purpose of this study was to use a metabolomics approach to gain a better understanding of the mechanisms driving the reprogramming of metabolic events involved in breast cancer pertaining to PEDF under various glycaemic loads. We employed gas chromatography-quadrupole mass spectrometry (GC-Q-MS) to investigate metabolic changes in the triple-negative breast cancer (TNBC) cell line MDA-MB-231 treated with PEDF under glycaemic loading. Multivariate and univariate analyses were carried out as indicative tools via MetaboAnalyst (V.5.0) and R packages to identify the significantly altered metabolites in the MDA-MB-231 cell line after PEDF exposure under glycaemic loading. A total of 61 metabolites were found, of which nine were selected to be distinctively expressed in MDA-MB-231 cells under glycaemic conditions and exhibited differential responses to PEDF (p < 0.05, VIP > 1). Abnormalities in amino acid metabolism pathways were observed. In particular, glutamic acid, glutamine, and phenylalanine showed different levels of expression across different treatment groups. The lactate and glucose-6-phosphate production significantly increased in high-glucose vs. normal conditions while it decreased when the cells were exposed to PEDF, confirming the positive influence on the Warburg effect. The TCA cycle intermediates, including malate and citric acid, showed different patterns of expression. This is an important finding in understanding the link of PEDF with metabolic perturbation in TNBC cells in response to glycaemic conditions. Our findings suggest that PEDF significantly influenced the Warburg effect (as evidenced by the significantly lower levels of lactate), one of the well-known metabolic reprogramming pathways in cancer cells that may be responsive to metabolic-targeted therapeutic strategies. Moreover, our results demonstrated that GC-MS-based metabolomics is an effective tool for identifying metabolic changes in breast cancer cells after glycaemic stress or in response to PEDF treatment.

Phytochemical Composition, Antioxidant and Antiproliferative Activities of Citrus hystrix, Citrus limon, Citrus pyriformis, and Citrus microcarpa Leaf Essential Oils against Human Cervical Cancer Cell Line

The essential oil derived from Citrus plants has long been used for medicinal purposes, due to its broad spectrum of therapeutic characteristics. To date, approximately 162 Citrus species have been identified, and many investigational studies have been conducted to explore the pharmacological potential of Citrus spp. oils. This study investigated the volatile constituents of essential oil distilled from the leaves of C. hystrix, C. limon, C. pyriformis, and C. microcarpa, using gas chromatography-quadrupole mass spectrometry. A total of 80 secondary compounds were tentatively identified, representing 84.88-97.99% of the total ion count and mainly comprising monoterpene (5.20-76.15%) and sesquiterpene (1.36-27.14%) hydrocarbons, oxygenated monoterpenes (3.91-89.52%) and sesquiterpenes (0.21-38.87%), and other minor chemical classes (0.10-0.52%). In particular, 27 compounds (1.19-39.06%) were detected across all Citrus species. Principal component analysis of the identified phytoconstituents and their relative quantities enabled differentiation of the Citrus leaf oils according to their species, with the loading variables contributing to these metabolic differences being identified. The Citrus leaf oils were tested for their antioxidant and antiproliferative activities using 2,2-diphenyl-1-picryl-hydrazylhydrate (DPPH) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. The results indicated that C. limon displayed the highest DPPH radical scavenging ability (IC50 value of 29.14 ± 1.97 mg/mL), while C. hystrix exhibited the lowest activity (IC50 value of 279.03 ± 10.37 mg/mL). On the other hand, all the Citrus oils exhibit potent antiproliferative activities against the HeLa cervical cancer cell line, with IC50 values of 11.66 μg/mL (C. limon), 20.41 μg/mL (C. microcarpa), 25.91 μg/mL (C. hystrix), and 87.17 μg/mL (C. pyriformis).

Aromatic Characteristics of Passion Fruit Wines Measured by E-Nose, GC-Quadrupole MS, GC-Orbitrap-MS and Sensory Evaluation

This study investigated the volatile composition and aromatic features of passion fruit wines using a combination of gas chromatography-quadrupole mass spectrometry (GC-qMS), gas chromatography-Orbitrap-mass spectrometry (GC-Orbitrap-MS), electronic nose (E-nose) and sensory evaluation. The results showed that these passion fruit wines possessed different aromatic features confirmed by E-nose. Seventeen sulfur compounds and seventy-eight volatiles were detected in these passion fruit wines using GC-Orbitrap-MS and GC-qMS, respectively. Forty-four volatiles significantly contributed to the overall wine aroma. These wines possessed passion fruit, mango, green apple, lemon and floral aromas confirmed by sensory evaluation. The partial least squares regression analysis indicated that sulfides, esters and terpenes, and terpenes mainly correlated to the passion fruit, mango and green apple aroma, respectively. Sulfur compounds significantly affected the aroma of passion fruit wine. The findings in this study could provide useful insight toward the quality control of passion fruit wine.

Microscale solid-liquid extraction: A green alternative for determination of n-alkanes in sediments

In this study, a green microscale solid-liquid extraction method using a miniaturized device combined with cleanup via dispersive micro-solid-phase extraction (MSLE-DµSPE) was developed for the determination by gas chromatography-quadrupole mass spectrometry (GC-MS) of n-alkanes in marine sediments. The main factors affecting the performance of this novel method were optimized using multivariate statistical tools. The MSLE-DµSPE method was validated considering the matrix-matched calibration, recovery, detection and quantification limits, ruggedness and accuracy. Under the optimum conditions, the method detection limits for n-alkanes ranged from 0.0051 to 0.0279 mg kg−1, and the quantification limits ranged from 0.0171 to 0.0930 mg kg−1. Correlation coefficients (R2) ≥0.99 were obtained for all compounds within the linear region (0.0025–0.200 mg L−1). The mean recovery for most n-alkanes ranged from 60.6 to 119%, with intraday and interday relative standard deviation (RSD) <20%. Evaluation of the MSLE-DµSPE method using Analytical Eco-Scale, Green Analytical Procedure (GAPI), and Analytical Greenness (AGREE) assessment metrics demonstrated the green potential of the developed method. Finally, the proposed method was successfully applied to marine sediment samples and the n-alkanes from C12 to C40 were detected with total concentrations in the range of 0.98–7.61 mg kg−1. This study represents the first application of a green microscale procedure to the analysis of n-alkanes in marine sediments.

Development and validation of a method for determining d-limonene and its oxidation products in vegetables and soil using GC–MS

A simple, rapid and effective gas chromatography–mass spectrometry method was developed for the simultaneous determination of d-limonene and its oxidation products in some vegetables and soils. Using the quick, easy, cheap, effective, rugged and safe (QuEChERS) method, the sample was extracted with n-hexane, purified with octadecylsilane (C18) and graphitized carbon black (GCB), and detected using gas chromatography-quadrupole mass spectrometry. The linear correlation coefficients of all analytes in the nine matrices were good (R2 > 0.995). At levels of 50, 100, and 1000 μg kg−1, the average recoveries ranged from 71.2 to 114.5%, while intra-day and inter-day precision were below 13.4%. The limits of detection (LODs) and the limits of quantification (LOQs) in all matrices for d-limonene and its five oxidation products were 1–16 and 4–48 μg kg−1, respectively. The residual levels of d-limonene can be well described by first-order kinetics. Dissipation in soil was microbially dominated, with half-lives of 1.95–2.84 days in the three soils and no residue in tomatoes. Its oxidation products were converted in soil mainly by microorganisms, with more trans-isomer production compared to cis-isomer. Moreover, no d-limonene residue was detected in tomatoes, and the persistence of d-limonene in soil was limited. The results of this study can provide data to understand the fate of d-limonene in tomato and soil and for further study its suitability as an environmentally friendly agrochemical.

Influence of Specific Power on the Solid and Liquid Products Obtained in the Microwave-Assisted Pyrolysis of End-of-Life Tires

In this work, chemical recycling as an alternative to conventional end-of-life treatments was studied. Two different types of end-of-life tires (ELT), truck tires and mix tires (50:50 mixture of passenger car and truck tires), were pyrolyzed in a batch microwave reactor. The influence of specific power (10, 20, and 30 W/g) on mass distribution was analyzed. The maximum liquid yield was attained at 10 W/g, while the maximum gas yield is obtained at 30 W/g. Liquid fractions were characterized by gas chromatography/quadrupole mass spectrometry (GC/qMS) to identify the main components, and major compounds were quantified. In all samples, limonene (3.76 ± 0.31–6.80 ± 2.37 wt. %) and BTEX (3.83 ± 0.20–1.19 ± 2.80 wt. %) were the main components. Major limonene concentration is obtained in oil produced from truck ELT while higher yields of aromatic compounds are obtained from mix ELT. The maximum BTEX concentration is obtained at 10 W/g being toluene the main compound with a concentration of 2.07 ± 0.42 and 4.63 ± 1.29 for truck and mix ELT, respectively. The separation and purification of these compounds will confer important value to these fractions. Higher yields of the solid fraction are produced when mix tires are pyrolyzed due to the higher concentration of ash in this type of ELT. Recovered carbon black was characterized by measuring the surface area.

Integrated differentiation of multiple trichloroethylene and tetrachloroethylene groundwater impacts using spatial concentration, biodegradation indices, chemical fingerprinting and carbon/chlorine isotope patterns

Conventional testing methods provide sufficient information to evaluate human or ecological risk. However, contaminant concentrations patterns alone provide only limited resolution of important liability issues, such as when and where did contaminant releases originate. Over the past few decades, scientists explored the isotope applications to better identify, delineate, and manage contaminants in the environment. Advanced chemical fingerprinting and isotope technologies revealed important linkages between isotope ratios and contaminant origins (e.g., chemical feedstock and manufacturing process). Studies of environmental weathering distinguished abiotic and biotic changes in the chemical composition and isotope patterns. The combined application of chemical and isotopic fingerprints offers powerful complementary lines of evidence for delineating contaminants, assessing risk, and identifying historical sources. This manuscript provides an integrated forensic approach that systematically links conventional environmental investigation data with specialized chemical fingerprinting and carbon/chlorine isotope methods for identifying the sources of groundwater impacts especially when multiple potential point and non-point sources exist. This paper focusses on chlorinated solvents. Specifically, it features the synoptic use of chemical concentration patterns and compound-specific isotope analysis (CSIA) as effective tools for confirming organic contaminant sources, characterizing environmental weathering, and answering a growing list of site-specific questions. Unlike conventional isotope methods, which can be both time-consuming and expensive, this paper presents an optimized analytical method for chlorine CSIA using gas chromatography-quadrupole mass spectrometry (GC-qMS). Chlorine isotopic composition for multiple analytes (e.g., tetrachloroethylene [PCE], trichloroethylene [TCE], dichloroethylene [DCE], and vinyl chloride [VC]) can be determined in one acquisition thus reducing analysis time and cost. Precise CSIA isotope values were achieved for chloroethylene concentrations between approximately 5 micrograms per liter (ug/l) and 100 ug/l for carbon and between approximately 30 ug/l to 1,000 ug/l for chlorine. The gradual improvement in CSIA methods better addresses the wide concentration range encountered in typical samples collected from groundwater aquifers with significant chlorinated solvent impacts. A case study is presented featuring a tiered forensic investigation using spatial chemistry and isotope patterns to evaluate commingled plumes of PCE and TCE.