Chromatography-quadrupole Mass Spectrometry Research Articles

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.

Comprehensive Phytochemical Analysis and Bioactivity Evaluation of Padina boergesenii: Unveiling Its Prospects as a Promising Cosmetic Component.

Marine macroalgae, such as Padina boergesenii, are gaining recognition in the cosmetics industry as valuable sources of natural bioactive compounds. This study aimed to investigate the biochemical profile of P. boergesenii and evaluate its potential as a cosmetic ingredient. Fourier-transform infrared (FTIR), gas chromatography-mass spectrometry (GCMS), and high-resolution liquid chromatography-mass spectrometry quadrupole time-of-flight (HRLCMS QTOF) analyses were employed to assess the functional groups, phycocompounds, and beneficial compounds present in P. boergesenii. Pigment estimation, total phenol and protein content determination, DPPH antioxidant analysis, and tyrosinase inhibition assay were conducted to evaluate the extracts' ability to counteract oxidative stress and address hyperpigmentation concerns. Elemental composition and amino acid quantification were determined using inductively coupled plasma atomic emission spectrometry (ICP-AES) and HRLCMS, respectively. FTIR spectroscopy confirmed diverse functional groups, including halo compounds, alcohols, esters, amines, and acids. GCMS analysis identified moisturizing, conditioning, and anti-aging compounds such as long-chain fatty alcohols, fatty esters, fatty acids, and hydrocarbon derivatives. HRLCMS QTOF analysis revealed phenolic compounds, fatty acid derivatives, peptides, terpenoids, and amino acids with antioxidant, anti-inflammatory, and skin-nourishing properties. Elemental analysis indicated varying concentrations of elements, with silicon (Si) being the most abundant and copper (Cu) being the least abundant. The total phenol content was 86.50 µg/mL, suggesting the presence of antioxidants. The total protein content was 113.72 µg/mL, indicating nourishing and rejuvenating effects. The ethanolic extract exhibited an IC50 value of 36.75 μg/mL in the DPPH assay, indicating significant antioxidant activity. The methanolic extract showed an IC50 value of 42.784 μg/mL. Furthermore, P. boergesenii extracts demonstrated 62.14% inhibition of tyrosinase activity. This comprehensive analysis underscores the potential of P. boergesenii as an effective cosmetic ingredient for enhancing skin health. Given the increasing use of seaweed-based bioactive components in cosmetics, further exploration of P. boergesenii's potential in the cosmetics industry is warranted to leverage its valuable properties.

Characteristic Structures of Different Stilbenes Distinguish the Impact on Ochratoxin A Biosynthesis Intermediate Pathway and Metabolites of Aspergillus carbonarius.

In this paper, we accurately pinpointed the inhibition sites of ochratoxin A (OTA) synthesis pathway in Aspergillus carbonarius acted by stilbenes from the perspective of oxidative stress and comprehensively explored the relationship between the physical and chemical properties of natural polyphenolic substances and their biochemical properties of antitoxin. To facilitate the application of ultra-high-performance liquid chromatography and triple quadrupole mass spectrometry for real-time tracking of pathway intermediate metabolite content, the synergistic effect of Cu2+-stilbenes self-assembled carriers was utilized. Cu2+ increased the generation of reactive oxygen species to accumulate mycotoxin content, while stilbenes had the inhibitory effect. The impact of the m-methoxy structure of pterostilbene on A. carbonarius was found to be superior to that of resorcinol and catechol. The m-methoxy structure of pterostilbene acted on the key regulator Yap1, downregulated the expression of antioxidant enzymes, and accurately inhibited the halogenation step of the OTA synthesis pathway, thus accumulating the content of OTA precursors. This provided a theoretical basis for the extensive and efficient application of a wide range of natural polyphenolic substances for postharvest disease control and quality assurance of grape products.

A Newly Developed Method-Based Xanthine Oxidoreductase Activities in Various Human Liver Diseases.

Studies evaluating xanthine oxidoreductase (XOR) activities in comprehensive liver diseases are scarce, and different etiologies have previously been combined in groups for comparison. To accurately evaluate XOR activities in liver diseases, the plasma XOR activities in etiology-based comprehensive liver diseases were measured using a novel, sensitive, and accurate assay that is a combination of liquid chromatography and triple quadrupole mass spectrometry to detect [13C2, 15N2]uric acid using [13C2, 15N2]xanthine as a substrate. We also mainly evaluated the association between the plasma XOR activities and parameters of liver tests, purine metabolism-associated markers, oxidative stress markers, and an inflammation marker. In total, 329 patients and 32 controls were enrolled in our study. Plasma XOR activities were generally increased in liver diseases, especially in the active phase, such as in patients with hepatitis C virus RNA positivity, those with abnormal alanine transaminase (ALT) levels in autoimmune liver diseases, and uncured hepatocellular carcinoma patients. Plasma XOR activities were numerically highest in patients with acute hepatitis B. Plasma XOR activities were closely correlated with parameters of liver tests, especially serum ALT levels, regardless of etiology and plasma xanthine levels. Our results indicated that plasma XOR activity might reflect the active phase in various liver diseases.

Optimization of microwave-enhanced extraction parameters to recover phenolic compounds and antioxidants from Corchorus olitorius leaves.

The online version contains supplementary material available at 10.1007/s11696-023-02771-x.

Signatory metabolomics biomarkers of stress, anxiety, and depression: a proof of concept for precision health among university students: A cross-sectional study

Purpose: The highly competitive nature of tertiary education and the pressure to perform academically have increased psychological morbidity like emotional distress. Untargeted metabolomics was used to analyze serum samples of university students for biomarkers and perturbated metabolism due to stress, anxiety, and depression (SAD).Methods: Depression, Anxiety, Stress Scale 21 (DASS-21) was used to assess the severity of SAD in university students. The metabolite fingerprint of each subject was obtained using liquid chromatography-mass spectrometry quadrupole time-of-flight (LC/MS QTOF). The signature metabolites for each trait were determined by projections to latent structures discriminant analysis (PLS-DA) with variable importance for the projection (VIP) score > 1.0 (P<0.05) and subjected to analysis using the area under the receiver operating characteristic curve (AUROC). Potential biomarkers with an area under the curve (AUC) value exceeding 0.65 were identified.Results: Various groups of glycerophospholipids were upregulated in the studied traits. On the other hand, metabolites such as glycocholic acid was upregulated in depression, while hypoxanthine was upregulated in anxiety, and PE-Cer(d14:1(4E)/22:1(13Z)) was upregulated in stress.Conclusion: To our knowledge, this is the first study to assess the relationship of the differentially expressed metabolites in university students of different categories of SAD using the DASS-21 screening tool in Malaysia as we move forward with precision health.

Human exposure to polycyclic aromatic hydrocarbons in the atmosphere of an agricultural area of central Chile and inhalation cancer risk assessments

Polycyclic aromatic hydrocarbons (PAHs) are persistent toxic substances prone to long-range atmospheric transport. Even in low concentrations, environmental exposure to PAHs can impact human health. In this study we aimed to i) investigate the occurrence of 15 polycyclic aromatic hydrocarbons (∑15PAHs), from August 2016 to January 2018, in the atmosphere of Molina, using polyurethane foam disks (PAS-PUF) in central Chile; and ii) perform deterministic and probabilistic (using Monte Carlo simulations) inhalation cancer risk assessments.Gas chromatography and tandem quadrupole mass spectrometry (GC- MS/MS) measured target PAHs. Results showed ∑15PAHs ranging from 2 ng m-3 to 108 ng m-3, with four-ring PAHs as the prevalent compounds, including phenanthrene (44%) and fluoranthene (24%). Winter season showed the highest PAH levels (increasing factor up to ∼8 times). PAHs diagnostic ratios showed the prevalence of pyrogenic combustion (winter) and petrogenic combustion (summer). Lifetime cancer risk assessments, using BaP-eq values, indicated an increased cancer risk for the exposed population considering different risk assessment approaches. Younger individuals were the most affected by an increased cancer risk at all sampling sites. The Monte Carlo probabilistic assessment indicated that infants and toddlers could be exposed to PAH air concentrations exceeding the cancer risk threshold in over 94% of the simulations. The coldest months in the studied region are critical for human exposure and health risk due to intense wood combustion. Indoor air can be even more relevant due to the chronic inhalation of the smoke and associated chemicals.

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).

Analysis of 12 Chemical Compounds And Pattern Recognition of Different Parts of Angelicae Sinensis Radix by Liquid Chromatography-Tandem Mass Spectrometry And Chemometrics Methods.

To evaluate the quality and quantify bioactive constituents in different parts of Angelicae Sinensis Radix, an efficient, high-speed, high-sensitivity high-performance liquid chromatography and triple quadrupole mass spectrometry method was used for simultaneous detection of 12 chemical compounds including L-tryptophan, chlorogenic acid, caffeic acid, ferulic acid, isoferulic acid, senkyunolide I, guanosine, proline, L-glutamine, γ-aminobutyric acid, glutamic acid, and arginine in 52 batches of Angelicae Sinensis Radix from Gansu, China. The established methods were validated by good linearity (R2≥0.9921), limits of detection (0.0001-0.0156 μg/mL), limits of quantitation (0.0006-0.0781 μg/mL), stability (RSD≤7.77%), repeatability (RSD≤6.79%), intra- and interday precisions (RSD≤6.00% and RSD≤6.39%, respectively) and recovery (90.90-107.16%). According to the quantitative results, the contents of the hydrophilic compounds were higher in the head, while the medium and weak polar components were mainly concentrated in the tail. Finally, principal component analysis results revealed that Angelicae Sinensis Radix could be divided into different medicinal sites based on polar components such as amino acids, nucleosides. The combination of liquid chromatography-tandem mass spectrometry and principal component analysis is a simple and reliable method for pattern recognition and quality evaluation of Angelicae Sinensis Radix.

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.

Targeted Metabolomics Reveals Impact of N Application on Accumulation of Amino Acids, Flavonoids and Phytohormones in Tea Shoots under Soil Nutrition Deficiency Stress

The abundant amino acids and flavonoids in tea crucially contribute to its particular flavor and many health benefits. The biosynthesis of these compounds is significantly affected by carbon and nitrogen metabolism, which is regulated by the nitrogen conditions in the soil. However, exactly how N-starved tea plants use N absorbed from the soil for the biosynthesis of amino acids, flavonoids, and phytohormones is still little known. Here, tea plants that were deficient in nitrogen owing to long-term non-fertilization were subjected to a higher N application (300 kg/ha) or lower N application rate (150 kg/ha) as well as organic or inorganic N. The levels of 30 amino acids, 26 flavonoids, and 15 phytohormone compounds were analyzed using ultra-high-performance liquid chromatography quadrupole mass spectrometry (UPLC-Q-MS/MS). It was found that a continuous lack of fertilization generated a minimal availability of soil N; as a result, the yield and the theanine and soluble sugar contents were greatly decreased, while the accumulation of seven flavonoid compounds (e.g., epigallocatechin, vitexin, and genistein) increased notably. The levels of theanine, glutamate, and aspartate significantly increased with the supply of N, whereas multiple amino acids, such as alanine, phenylalanine, valine, etc., decreased, indicating that the absorption of nitrogen is preferentially used for the biosynthesis of theanine and glutamate-derived amino acids by a N-starved tea plant. Meanwhile, the changes in the accumulation of flavonoids in tea shoots with various N supplies clarified that a lower N application rate has a negative influence while higher N has a positive effect on the synthesis of flavonoids in a N-starved tea plant. In addition, following N supply, the N-deficient tea plant accumulated ABA (Abscisic acid), SA (Salicylic acid), JA (Jasmonic acid), CKs (Cytokinins), and ACC (1-Aminocyclopropanecarboxylic acid), at 2.03, 1.14, 1.97, 1.34, and 1.26 times, respectively, as high as those in a tea plant with normal fertilization. Furthermore, we performed the correlation network analysis among amino acids, flavonoids, and phytohormones. Its result confirmed that glutamate, aspartate, and hydroxyproline showed a significantly positive correlation with 8, 11, and 8 flavonoid compounds, respectively. Cis-OPDA (cis-12-oxo-phytodienoic acid) was also significantly negatively correlated with eight flavonoid compounds (e.g., naringenin, myricetin, and quercetin). Collectively, our tests suggested that a lower N application promotes the biosynthesis of the theanine and amino acids involved in theanine synthesis, thus inhibiting the accumulation of other amino acids, while greater N application promotes flavonoids in a N-starved tea plant.

Person-portable gas chromatography-toroidal ion trap mass spectrometry analysis of coffee bean volatile organic compounds

Analysis of roasted coffee bean volatile organic compounds (VOCs) was performed using person-portable gas chromatography–toroidal ion trap mass spectrometry (ppGC–TMS). Chromatographic separation performance and mass spectra were compared and contrasted with benchtop gas chromatography–quadrupole time-of-flight mass spectrometry (GC–QTOFMS) and gas chromatography–quadrupole mass spectrometry (GC–QMS). The tentative identification of about 50 analytes was established in benchtop analysis, based on accurate MS data, MS spectrum matching and retention indices, and contrasted with 20 individual analyte peaks similarly recognised in ppGC–TMS analysis. This study suggests the suitability of ppGC–TMS analysis for rapid coffee VOC profiling with minimal sample preparation, using selective key chemical markers, with potential use for on-site process monitoring and roasting optimisation.

Investigation of partition coefficients and fingerprints of atmospheric gas- and particle-phase intermediate volatility and semi-volatile organic compounds using pixel-based approaches

Ambient gas- and particle-phase intermediate volatility and semi-volatile organic compounds (I/SVOCs) of Beijing were analyzed by a thermal desorption comprehensive two-dimensional gas chromatography quadrupole mass spectrometry (TD-GC × GC-qMS). A pixel-based scheme combing the integration-based approach was applied for partition coefficients estimation and fingerprints identification. Blob-by-blob recognition was firstly utilized to characterize I/SVOCs from the molecular level. 412 blobs in gas-phase and 460 blobs in particle-phase were resolved, covering a total response of 47.5% and 43.5%. A large pool of I/SVOCs was found with a large diversity of chemical classes in both gas- and particle-phase. Acids (8.5%), b-alkanes (5.8%), n-alkanes (C8-C25, 5.3%), and aromatics (4.4%) were dominant in gas-phase while esters (7.0%, including volatile chemical product compounds, VCPs), n-alkanes (C9-C34, 5.7%), acids (4.6%), and siloxanes (3.6%) were abundant in particle-phase. Air pollutants were then evaluated by a two-parameter linear free energy relationship (LFER) model, which could be further implemented in the two-dimensional volatility basis set (2D-VBS) model. Multiway principal component analysis (MPCA) and partial least squares-discriminant analysis (PLS-DA) implied that naphthalenes, phenol, propyl-benzene isomers, and oxygenated volatile organic compounds (OVOCs) were key components in the gas-phase under different pollution levels. This work gives more insight into property estimation and fingerprints identification for complex ambient samples.

Extraction of glucocorticoids from water into acetonitrile using polyol induced extraction with ultra performance liquid chromatography and triple quadrupole mass spectrometry (PIE-UPLC-MS-MS)

Polyol-induced Extraction (PIE) was used for the extraction and UPLC-MS-MS was used for the analysis of glucocorticoids in water. The focus of this work was to demonstrate PIE as an effective technique that allows extraction of solutes between miscible solutes using a phase separating agent, with an example analysis of glucocorticoids. In this work glycerol is used as the mass separating agent in the extraction of glucocorticoids from water into acetonitrile. Eight glucocorticoids were extracted by PIE and analyzed by UPLC-MS-MS. Extraction conditions were optimized, and extraction results were compared to non-extracted glucocorticoid standards and to literature methods. Extraction was optimized at 0 °C, in 10 mL of a 1:1 ACN/Water mixture 2 mL of glycerol added as phase separating agent. Calibration curves showed overall correlation of r 2 > 0.99. Precent relative standard deviation below 4%was obtained for all analytes. Limits of detection were obtained between 3–4 ng/mL by the IUPAC method and 40–200 ng/mL by a propagation of errors method. PIE is demonstrated to be a simple and quick method for extracting glucocorticoids from water into a miscible polar solvent, acetonitrile.

Open Characterization of Vaping Liquids in Canada: Chemical Profiles and Trends.

Currently, there is a lack of comprehensive data on the diversity of chemicals present in vaping liquids. To address this gap, a non-targeted analysis of 825 vaping liquids collected between 2017 and 2019 from Canadian retailers was conducted. Prior to mass spectrometry analysis, samples were diluted 1:500 v/v with methanol or acetonitrile. Chemical compound separation and analysis was carried out using gas chromatography and triple quadrupole mass spectrometry (GC-MS/MS) systems operated in the full scan mode and mass range of 35–450 m/z. Mass spectrum for each sample was obtained in electron ionization at 70 eV and processed. Non-targeted identification workflow included use of automated mass spectral deconvolution and identification system (AMDIS), where required, as well as a number of commercially available spectral libraries. In order to validate identities, an in-house database of expected compounds previously detected in vaping liquids was used along with genuine analytical standards for compounds of interest. This resulted in a dataset of over 1,500 unique detected chemicals. Approximately half of these chemical compounds were detected only once in a single product and not in multiple products analyzed. For any sample analyzed, on average, 40% of the chemical constituents appeared to have flavouring properties. The remainder were nicotine and related alkaloids, processing, degradation or indirect additives, natural extractives and compounds with unknown roles. Data published here from the project on the Open Characterization of vaping liquids is unique as it offers a detailed understanding of products’ flavour chemical profiles, the presence and frequency of chemicals of potential health concern, as well as trends and changes in products’ chemical complexity over a three-year period. Non-targeted chemical surveillance such as this present valuable tools to public health officials and researchers in responding to emergent issues such as vaping associated lung injury or informing chemical based strategies which may be aimed at addressing product safety or appeal.

Comparison of gas- and liquid chromatography-mass spectrometry for trace analysis of anilines in groundwater

ABSTRACT Three chromatographic procedures were investigated regarding their potential for the quantification of aniline and 19 of its methylated and chlorinated derivatives in groundwater. These methods were based on liquid-liquid-extraction in combination with gas chromatography and single quadrupole mass spectrometry (GC/MS) according to German standard DIN 38407–16:1999 and its extension using tandem mass spectrometry (GC/MS-MS), both following liquid–liquid extraction, and as third alternative the direct injection of the water sample into a liquid chromatograph coupled to tandem mass spectrometry (LC/MS-MS). Results were compared using fortified water and real-world contaminated groundwater used in an interlaboratory comparison. It could be shown that GC/MS and GC/MS-MS yielded results deviating less than 10% from each other, while all three procedures displayed quantification results deviating less than 15% from the intercomparison reference values in case of each analyte in the concentration range between 1 and 45 µg L−1. Though GC/MS-MS displays a ten-fold higher sensitivity than single quadrupole GC/MS, the precision of both methods in the concentration range was similar. LC/MS-MS has the advantage of no further sample preparation due to direct injection and leads for methylanilines and meta-, para-substituted chloroanilines to results sufficiently equivalent to the standardised GC/MS method. However, LC/MS-MS is not suitable for ortho-chloroaniline derivatives due to significantly lower ion yields than meta- and para-substituted chloroanilines.

Unraveling the difference in aroma characteristics of Huangjiu from Shaoxing region fermented with different brewing water, using descriptive sensory analysis, comprehensive two-dimensional gas chromatography–quadrupole mass spectrometry and multivariate data analysis

To investigate the specific difference in aroma characteristics of Huangjiu (Chinese rice wine) in Shaoxing region fermented with different brewing water, descriptive sensory analysis, comprehensive two-dimensional gas chromatography–quadrupole mass spectrometry (GC × GC–qMS) and multivariate statistical analysis were employed. The descriptive sensory analysis proved that Huangjiu fermented with Jianhu water had higher overall aroma intensity, and was more prominent in ester, sweet and alcoholic aroma than those fermented with deionized water and Nenjiang water. The results of aroma components analysis by GC × GC–qMS showed that the Huangjiu fermented with Jianhu water had higher concentration of some key aroma compounds, such as ethyl butyrate (OAV: 29–196), isoamyl acetate (OAV: 11–18) and ethyl hexanoate (OAV: 38–47). The multivariate statistical analysis further confirmed that 14 compounds could be used as key markers to distinguish the Huangjiu samples fermented with different brewing water. The correlation network between the volatile compounds in Huangjiu and the inorganic components in water indicated that the ions played an important role in the formation of the difference in aroma characteristics among the samples.

Investigating Bacterial Volatilome for the Classification and Identification of Mycobacterial Species by HS-SPME-GC-MS and Machine Learning.

Species of Mycobacteriaceae cause disease in animals and humans, including tuberculosis and leprosy. Individuals infected with organisms in the Mycobacterium tuberculosis complex (MTBC) or non-tuberculous mycobacteria (NTM) may present identical symptoms, however the treatment for each can be different. Although the NTM infection is considered less vital due to the chronicity of the disease and the infrequency of occurrence in healthy populations, diagnosis and differentiation among Mycobacterium species currently require culture isolation, which can take several weeks. The use of volatile organic compounds (VOCs) is a promising approach for species identification and in recent years has shown promise for use in the rapid analysis of both in vitro cultures as well as ex vivo diagnosis using breath or sputum. The aim of this contribution is to analyze VOCs in the culture headspace of seven different species of mycobacteria and to define the volatilome profiles that are discriminant for each species. For the pre-concentration of VOCs, solid-phase micro-extraction (SPME) was employed and samples were subsequently analyzed using gas chromatography–quadrupole mass spectrometry (GC-qMS). A machine learning approach was applied for the selection of the 13 discriminatory features, which might represent clinically translatable bacterial biomarkers.