Gas Chromatography Research Articles

An exploratory study of volatile and semi-volatile organic compounds in PM2.5 atmospheric particles from an outdoor environment in Brazil.

The development of methods for determining volatile and semi-volatile organic compounds in public spaces has become necessary to identify potential health and environmental risks. This study presents a practical methodology for sampling, extracting, detecting, and identifying these compounds in a vehicular traffic region in Belo Horizonte, Brazil. The methodology uses direct-immersion solidphase microextraction (DI-SPME) and static headspace (SHS) to extract SVOCs/VOCs. Comprehensive time-of-flight gas chromatography mass spectrometry (GC×GC/Q-TOFMS) and gas chromatography coupled to mass spectrometry (GC/MS) were used to detect and identify compounds. The analysed samples, collected with a high-volume sampler (Hi-Vol) with quartz filters and in which particulate matter (PM2.5) was retained, showed the presence of more than 200 compounds, both biogenic (natural origin) and anthropogenic (human origin). Regarding the distribution of chemical classes, aromatic compounds were predominantly found at 29.2%, followed by esters at 20.8%, non-aromatic hydrocarbons at 5.6%, and carboxylic acids at 9.4%. Static headspace gas chromatography (HS-GC) enabled the identification and quantification of 21 volatile compounds, including BETX, dichloromethane, chloroform, and naphthalene, which are currently regulated by the US Environmental Protection Agency (EPA).

The Emergence of a Novel Synthetic Nicotine Analog 6-Methyl Nicotine (6-MN) in Proclaimed Tobacco- and Nicotine-Free Pouches Available in Europe.

A new nicotine delivery system in the form of tobacco-free nicotine pouches was introduced in Europe in 2019. These nicotine bags did not fall under the Tobacco Products Directive (TPD) II, which brought forward regulatory requirements for both cigarettes, related products, and e-liquids. As these pouches did not fall under the scope of the TPD, it was up to the member states to decide which action to be taken if any. Some EU member states banned these nicotine pouches, while others put restrictions on the amount of nicotine, warning messages, and presentation and packaging of the product, and some member states did not take any action. Likely as a result of the ban or restrictions, soon after also, tobacco and nicotine-free pouches became available in the European Union (EU). Early 2024, "NoNIC" pouches, claiming to be tobacco- and nicotine-free, became available on the European market. These pouches are promoted online and clearly target a younger population with a youth-appealing package design and enticing flavors. Upon analysis of different samples utilizing gas chromatography coupled to MS (GC-MS), liquid chromatography coupled to high-resolution tandem mass spectrometry (HRAM LC-MS2), and nuclear magnetic resonance spectroscopy (NMR), it was demonstrated that these pouches were indeed devoid of nicotine but contained the synthetic nicotine homolog 6-methyl nicotine (6-MN) and this up to 20 mg per pouch. Nonetheless, a part of a likely unaware/misled young adult subpopulation has easy access to these products, containing a novel molecule for which limited to no clinical effects are known.

Improved Method for Methane Pyrolysis Rate Measurement using Molten Metal Catalysts for Turquoise Hydrogen Production

Abstract To develop low-$$\hbox {CO}_2$$ CO 2 emission ferrous metallurgical process, $$\hbox {H}_2$$ H 2 -based ironmaking processes are being actively developed. Several technologies are being developed to provide a sufficient mass of $$\hbox {H}_2$$ H 2 in an environmentally friendly manner. One of such processes is “turquoise” $$\hbox {H}_2$$ H 2 , based on a natural gas pyrolysis such as $$\hbox {CH}_4$$ CH 4 (g) $$\rightarrow $$ → 2$$\hbox {H}_2$$ H 2 (g) + C(s), thereby minimizing $$\hbox {CO}_2$$ CO 2 emission. The reaction could be catalyzed using molten metals in a bubble column reactor. Therefore, the selection of the molten metal catalyst is important for enhancing the reaction efficiency and for minimizing the production cost. In the previous research of the present authors, a new methodology for the pyrolysis rate measurement was introduced by employing an electromagnetic levitation heating of catalytic molten metals followed by quadrupole mass spectrometer (QMS) analysis to assist in the selection of the catalyst metal. However, a potential source of error in this technique was identified. Therefore, two modifications of the methodology are reported in the present study: (1) changing the heating and feed gas supply patterns and (2) gas analysis technique from QMS to Gas Chromatography (GC). Accordingly, the reported pyrolysis rate of pure In, Ga, Bi, Sn, and Cu of the previous study was revised in the present study. It was revealed that Ga and In emitted non-negligible amounts of $$\hbox {H}_2$$ H 2 upon heating, even without the fuel gas ($$\hbox {CH}_4$$ CH 4 ). This was regarded as a noise in the $$\hbox {H}_2$$ H 2 signal measured by GC. On the other hand, Cu, Sn, and Bi did not show the noticeable $$\hbox {H}_2$$ H 2 (noise). The modified method provides $$\hbox {H}_2$$ H 2 production rate by the pyrolysis, by separating the noise in the regime of the chemical reaction control at the surface of the molten metals. $$1^\text {st}$$ 1 st -order reaction was confirmed. Graphical Abstract

Refinement of Retention Indices in Gas Chromatography for a Number of Substituted Phenols

Substituted phenols, including chlorophenols, are important analytes, particularly in the context of environmental analysis. Chlorophenols are formed during the disinfection of drinking water by chlorination and are important water pollutants. Gas chromatography–mass spectrometry (GC-MS) is an important method for the analysis of chlorophenols. Retention indices are used in GC-MS analysis to improve the accuracy of identification. Our research reveals that the retention indices currently available for substituted phenols are erroneous in a number of cases. We report reliable retention index values for pentafluorophenol, 5-methoxy-2-nitrophenol, 4-cyanophenol (stationary phase: 5%-phenyl-polymethylsiloxane), 3-methoxyphenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2,3-dichlorophenol, 2,5-dichlorophenol, 2,6-dichlorophenol, 3,4-dichlorophenol, 3,5-dichlorophenol, 2,3,5-trichlorophenol, 2,3,6-trichlorophenol, 2,4,5-trichlorophenol, and 2,4,6-trichlorophenol (stationary phase: polyethylene glycol modified with 2-nitroterephthalic acid). The structures of the standard samples were confirmed, and measurements were performed under various conditions. The analysis of the causes of the incorrect records appearing in the well-known NIST database was also carried out.

Wound healing potential of mouth gel containing isopimarane diterpene from Kaempferia galanga rhizomes for treatment of oral stomatitis

Background Oral ulcers have an impact on 25% of the global population including patients who are suffering from chemotherapy and radiotherapy treatments. Kaempferia galanga L. has been traditionally used for treatment of mouth sores and tongue blisters. However, the wound healing study of isopimarane diterpenes isolated from K. galanga is still limited. Objective This study aims to evaluate the wound healing potential of 6β-acetoxysandaracopimaradiene-1α,9α-diol (KG6), a compound isolated from Kaempferia galanga, by examining its biological activities. Additionally, we investigate the physicochemical and biological properties of (KG6) in formulated mouth gels. Methods The KG6 mouth gels at 0.10%, 0.25% and 0.50% w/w were formulated using sodium carboxymethylcellulose as a gelling agent, and their physicochemical and biological stabilities were assessed through a heating-cooling acceleration test. The quantification of KG6 contents in KG6 mouth gels was determined using gas chromatography. Both KG6 and KG6 mouth gels were evaluated for their wound healing properties including cell proliferation, cell migration, and antioxidant activity (H2O2-induced oxidative stress) in human gingival fibroblast (HGF-1-ATCC CRL-2014) (HGF-1). In addition, the anti-inflammatory activity against nitric oxide (NO) production was investigated in macrophage cells (RAW 264.7). Results After KG6 mouth gels were incubated under heating-cooling acceleration condition, the physicochemical properties of the KG6 mouth gels remain stable across various parameters, including appearance, color, smell, texture, pH, viscosity, separation, and KG6 content. The biological studies indicated that the KG6 compound possessed good wound healing potential. The 0.50% KG6 mouth gel exhibited marked anti-inflammatory effect by inhibiting NO production with an IC50 of 557.7 µg/ml, comparable to that of Khaolaor mouth gel, a positive control. The 0.25% KG6 mouth gel increased HGF-1 cell proliferation to 101.7–103.5%, whereas all formulations of KG6 mouth gel enhanced HGF-1 cell migration to 94.7–98.9%, higher than Khaolaor mouth gel (73.5%). Moreover, 0.50% KG6 mouth gel also showed a good antioxidant effect under H2O2-induced oxidative stress. Conclusion This study substantiates the significant biological activities related to the wound healing property of 0.50% KG6 mouth gel for treatment of aphthous ulcers and oral stomatitis from chemotherapy and radiotherapy treatments.

Sijunzi San alleviates the negative energy balance in postpartum dairy cows by regulating rumen fermentation capacity

IntroductionPostpartum dairy cows are susceptible to negative energy balance caused by decreased feed intake and the initiation of lactation. Sijunzi San, a famous Chinese traditional herbal formulation, can promote gastrointestinal digestion and absorption and improve disorders of intestinal microbiota. Therefore, we hypothesized that Sijunzi San might alleviate negative energy balance in postpartum dairy cows by modulating the structure of the rumen microbiota and enhancing its fermentation capacity.MethodsLiquid chromatography-mass spectrometry (LC–MS/MS) was utilized in vitro to identify the main active ingredients in the Sijunzi San. Techniques including in vitro ruminal fermentation, gas chromatography, and 16S rRNA high-throughput sequencing were employed to evaluate their effects on the structure of the rumen microbiota. To test their in vivo effects, sixteen postpartum Holstein dairy cows, with similar body condition and parity, were randomly assigned to two groups, with 8 cows per group. The CONT group was fed a basic diet, while the SJZS group received an additional 300 g/d of Sijunzi San along with the basic diet, continuously for 7 days. ELISA and untargeted metabolomics using ultra-high-performance liquid chromatography-tandem mass (UHPLC–MS/MS) were employed to assess the impacts on immunoglobulin levels, fat mobilization, and the blood metabolome in postpartum dairy cows.ResultsDoses of 100 to 500 mg of the Sijunzi San significantly enhanced gas production, microbial protein (MCP), and short-chain fatty acid (SCFA) levels, while notably reducing pH and NH3-N content (p < 0.05), exhibiting a significant dose-dependent relationship. The results revealed that 500 mg of the prescription significantly increased the abundances of the Succiniclasticum and Prevotella genera and notably decreased the abundances of the Christensenellaceae_R-7_group, Muribaculaceae, UCG-005, Comamonas, and F082 genera (p < 0.05). Succiniclasticum and Prevotella showed a significant positive correlation with ruminal SCFAs, whereas UCG-005 exhibited a significant negative correlation with them (p < 0.05). Additionally, Luteolin and Glycitein were significantly positively correlated with Prevotella, while Licochalcone B and Liquoric acid were significantly negatively correlated with Comamonas (p < 0.05). Subsequently, the prescription significantly increased the concentrations of IgA, IgM, and microsomal triglyceride transfer protein (MTTP) in the blood (p < 0.01), while reducing the levels of ketones (KET) (p < 0.05), non-esterified fatty acids (NEFA), and triglycerides (TG) (p < 0.01). Notable alterations were observed in 21 metabolites in the blood metabolome (p < 0.05). Additionally, metabolic pathways associated with linoleic acid metabolism and steroid hormone biosynthesis were significantly affected.DiscussionThe findings suggest that administering Sijunzi San to dairy cows during the postpartum period can ameliorate negative energy balance by stimulating rumen fermentation and modifying the composition and abundance of the rumen microbiota.

Synergistic Pain-Reducing Effects of Bixa orellana (Chronic® and Chronic In®) and Cannabidiol-Rich Cannabis sativa Extracts in Experimental Pain Models

Background: The present study aimed to evaluate the potential synergy between pharmaceutical formulations containing Bixa orellana L. (granulated—CHR OR and injectable nanodispersion—CHR IN) in conjunction with a cannabidiol (CBD)-rich extract of Cannabis sativa L. (CSE) on experimental pain models in Wistar rats. Methods: Chemical analysis was performed using gas chromatography (GC-MS). The pain tests employed were acetic acid-induced writhing (injection i.p. of 0.9% acetic acid), formalin (solution 1%), hot plate (55 ± 0.5 °C), and cold-water tail withdrawal tests. Results: Chemical analyses by chromatography confirmed that the oil from B. orellana is rich in δ-tocotrienol (72.0 ± 1.0%), while the oil from Cannabis sativa highlighted the presence of cannabidiol (CBD). The results from the experimental pain tests indicated that the combined administration of formulations containing Bixa orellana and C. sativa, such as the granulated CHR OR (400 mg/kg, orally) with CSE (40 mg/kg, orally) or the nanodispersion CHR IN (10 mg/kg, intramuscularly) with CSE (40 mg/kg, orally), demonstrated significant results (p < 0.001) in pain reduction. Although the formulations containing Bixa orellana extract showed statistical significance in the tests when used in isolation, their effects were inferior compared to the combined use with CSE or the isolated use of CSE. These findings suggest that combining formulations containing extracts of these plant species may represent a viable therapeutic option, considering the synergistic action in reducing pain under the experimental conditions employed. Conclusions: these results imply that combining the phytocomplexes present in B. orellana and C. sativa may be a promising approach for pain treatment.

GC–MS, 1H and 13C NMR, and physiochemical properties of oils of Dacryodes Edulis and Persea Americana

A comparative investigation was carried out on the seed oils of P. americana and D. edulis for their physiochemical properties and spectroscopic properties. Oils were extracted from the respective powdered seeds using Soxhlet extraction technique giving 18.63% and 45.49% yields for P. americana and D. edulis, respectively. The seed oils were subjected to physiochemical analysis using standard protocols as prescribed by the American Oil Chemist Society (AOCS) and the American Society for Testing and Materials (ASTM). The fatty acid content was determined using Gas Chromatography, Proton (1H) and Carbon-13 (13C) Nuclear Magnetic Resonance spectroscopy. The results indicates that linoleic acid is the most unsaturated fatty acid, while stearic acid is the most saturated fatty acid in both oils. Unsaturated fatty acid peaks for olefinic H were observed at 5.34 and 5.31 ppm for P. americana and at 5.43 and 5.32 ppm for D. edulis oils in 1H-NMR. For 13C-NMR, the presence of C with triple bond attached to an alkyl group was observed at 85 ppm for the P. americana, while similar peak was observed for D. edulis at 128.21 to 130.1 ppm. The chemical characterization of the oils gave iodine values of 51.86 mgI2/g for P. americana oil and 48.72 mgI2/g for D. edulis oil. Similarly, acid values of 3.45 mg KOH/kg and 5.76 mg KOH/kg were obtained for P. americana and D. edulis seed oils respectively. The physiochemical and spectroscopic results obtained showed that P. americana and D. edulis seed oils have the potential for use in a number of industrial applications.

Selective Adipose Cryolysis for Reduction of Lingual Tissue in a Porcine Model.

Oropharyngeal fat volume is associated with obstructive sleep apnea (OSA) severity. Selective adipose cryolysis may produce cold-induced adipose cell death while sparing surrounding tissues. This study explored (1) similarities in tongue fat between porcine and human models and (2) the feasibility and potential reduction of lingual fat using selective adipose cryolysis. Porcine model. Preclinical research laboratory under IACUC-approved protocols. Anatomical, histological, and biochemical characterizations of tongue tissue from 6 porcine and 4 human cadaver specimens were conducted to establish comparative frameworks. Comparison of fat distribution and composition was conducted via image analysis of histological sections as well as gas chromatography analysis of fatty acid composition. Safety and efficacy of selective adipose cryolysis were evaluated in an additional 16 porcine animals using a prototype cooling system. Histological analysis examined tissue response at 3, 6, 30, and 45 d posttreatment. Comparative analysis revealed similar fat distribution and composition between human and porcine tongues. Selective adipose cryolysis induced progressive reduction in treated area tongue fat content at all timepoints, from 42% at baseline to 32% (t = 3 d) and 14% (t = 30 d), accompanied by macrophage infiltration, crown-like structure formation, and tissue remodeling. Selective adipose cryolysis holds promise as a targeted therapeutic approach for reducing lingual fat in humans. The porcine model may provide valuable insight into treatment mechanisms and support initial translational work. Further research is warranted to elucidate long-term treatment outcomes and optimize clinical implementation strategies, with the goal of improving management of OSA in humans.

Assessment of heavy metals, PAHs, and pesticide levels in yerba mate on the European market.

Although yerba mate has been known and used for hundreds of years, not all of its properties have been fully understood yet. Yerba mate is a source of many desirable substances, but it may also contain toxic metals and other substances that are harmful to health. Fifteen samples of yerba mate tea from three South American countries were analyzed. The content of Cr, Ni, and Cd was determined using the AAS technique, while the PHA's content was determined with the gas chromatography method. Our studies show that some of the analyzed substances present in Ilex paraguariensis may exceed their acceptable levels specified in European standards established for the given substances. All analyzed samples contained the determined metals, where the concentrations of individual elements ranged from 1.92 ± 0.38 to 0.12 ± 0.05µg/g (for Cr), from 4.86 ± 0.28 to 1.72 ± 0.14µg/g (for Ni), and from 0.0008 ± 0.000 to 0.0695 ± 0.0745µg/g (for Cd). The total PAH content ranged from 0.064 to 0.585mg/kg. Yerba mate samples from Brazil were characterized by a lower PAH content (0.064-0.254mg/kg), compared with mate from Argentina and Paraguay (0.084-0.374 and 0.197-0.585mg/kg, respectively). Pesticide residues were found only in samples from Argentina and Paraguay, while samples from Brazil did not contain those compounds. Only four active substances belonging to the group of herbicides, fungicides, and insecticides were detected, two of them not approved for use in the EU: chlorpyrifos and fenbuconazole. The most frequently detected compounds in yerba mate samples were pendimethalin (in four samples), fluazifop-p-butyl and fenbuconazole (detected in two samples), and chlorpyrifos (in one sample).

Chemical Composition and Biological Activities of St John’s Wort (Hypericum perforatum L.) Essential Oil from Bulgaria

Since ancient times, essential oils obtained from various aromatic plants have been utilized as bioactive ingredients in medicines, foods and cosmetics. The present study aimed to investigate the chemical composition and biological activities of St John’s Wort (Hypericum perforatum L.) essential oil (SJW EO) from Bulgaria, which is known to possess various biological properties. Gas chromatography and mass spectrometry (GC–MS) analysis, determination of antioxidant activity (by the ABTS method), an antimicrobial activity test and an in vitro anti-inflammatory activity test were performed. The main classes of compounds identified by GC–MS analysis were monoterpenes (43.55%), followed by sesquiterpenes (36.81%) and alkanes (16.92%). The predominant chemical components of SJW EO were α-pinene (27.52%), followed by β-pinene (10.08%), β-caryophyllene (6.77%), germacrene D (6.37%) and caryophyllene oxide (4.48%). The highest antibacterial activity was observed against the Gram-negative bacteria Klebsiella pneumoniae ATCC 13883 (inhibition zone of 12.0 mm) and Pseudomonas aeruginosa ATCC 9027 (inhibition zone of 11.0 mm). SJW EO exhibited significant in vitro anti-inflammatory activity, as the results demonstrated that its anti-inflammatory effect was stronger than those of the conventional anti-inflammatory drugs Prednisolon Cortico and acetylsalicylic acid (Aspirin), which were used as controls (all in concentration of 1 mg/mL). The obtained results demonstrated that Bulgarian SJW EO can be used as an active ingredient in the composition of new products for the pharmaceutical and cosmetic industries.

Classification of Plant-Based Drinks Based on Volatile Compounds

The increasing popularity of plant-based drinks has led to an expanded consumer market. However, available quality control technologies for plant-based drinks are time-consuming and expensive. Two alternative quality control methods, gas chromatography with ion mobility spectrometry (GC-IMS) and an electronic nose, were used to assess 111 plant-based drink samples. Principal component analysis (PCA) and linear discriminant analysis (LDA) were used to compare 58 volatile organic compound areas of GC-IMS gallery plots and 63 peptide sensors of the electronic nose. PCA results showed that GC-IMS was only able to completely separate one sample, whereas the electronic nose was able to completely separate seven samples. LDA application to GC-IMS analyses resulted in classification accuracies ranging from 15.4% to 100%, whereas application to electronic nose analyses resulted in accuracies ranging from 96.2% to 100%. Both methods were useful for classification, but each had drawbacks, and the electronic nose performed slightly better than GC-IMS. This study represents one of the first studies comparing GC-IMS and an electronic nose for the analysis of plant-based drinks. Further research is necessary to improve these methods and establish a rapid, cost-effective food quality control system based on volatile organic compounds.

Effect of Phosphorus Deprivation on Fatty Acid Synthesis in Scenedesmus subspicatus Microalgae from Rostherne Mere

Numerous studies have examined the feasibility of using microalgae as a long-term source of biofuel. This helped us to determine how different amounts of phosphorus changed the growth of lipids in Scenedesmus subspicatus, a freshwater microalga. This study examined the effects of various phosphorus concentrations on the biochemical makeup of algae, particularly the production of proteins and carbohydrates. When there was insufficient phosphorus, the investigation observed a significant increase in lipids and productivity of S. subspicatus. Additionally, gas chromatography was used to examine the fatty acid profiles of the green algae thoroughly. When Scenedesmus species were tested at different cell densities, the highest amount of chlorophyll was found to be 0.89 mg/L. The amounts of fatty acids in algae grown with 0.4 and 0.04 P of phosphorus were strongly correlated, as shown by the Pearson linear correlation coefficients. Gas chromatography analysis revealed that the major saturated fatty acids were stearic acid (C18:0) and palmitic acid (C16:0). In addition, confirming the presence of several unsaturated fatty acids (C16:3, C18:1, C18:2, and C18:3) has helped us learn more about S. subspicatus’s complex lipid profile of S. subspicatus and how well it can be used to produce biofuels.

Nutritional and Antinutritional Evaluation of the Pulp and Seed of Terminalia catappa l. (Tropical Almond) Fruit and Physicochemical Properties of Its Seed Oil

Aims: This study aimed at determining the nutritional and antinutritional composition of the pulp and seeds as well as physicochemical characteristics of the seed oil of Terminalia catappa L. (tropical almond). Methodology: The analyses were done in the Agroecology and life science laboratory of the University of Buea between June 2023 and May 2024. The experimental design was employed. Oil was extracted using soxhlet method. UV-visible spectrophotometer was used for nutritional and antinutritinal analyses; while gas chromatography and titrimetry were used to analyse the fatty acid profile and physicochemical properties of the seed oil respectively. Results: Results revealed that the seeds recorded more concentrated energy (596.28 Kcal/100g) than the pulps (403.42 Kcal/100g). Total phenolic (133.70 ± 0.15 mg/100g), tannin (77.90 ± 0.01 mg/100g), oxalate (15.01 ± 0.01 mg/100g) and phytic acid (2.81 ± 0.06 mg/100g) contents were displayed by the pulp and 29.70 ± 0.25, 18.00 ± 0.07, 20.92 ± 0.07 and 1.88 ± 0.01 mg/100g, respectively for seeds. The abundant minerals in the pulp were K, Ca, Na, and P, those in the seeds were Mg, K, P and Fe. The Acid value, Saponification value, Iodine value, Peroxide value and P-anisdine value of the seed oil were 2.24 ± 1.16 mgKOH/g, 222.2 ± 3.11 mgKOH/g, 78.50 ± 0.54 gI2/100g, 5.50 ± 0.71 mEq/kg and 3.65 ± 0.23, respectively. Fatty acid profiling showed 66.68% unsaturated fatty acids of which 19.86% and 9.81% were linoleic and linolenic, respectively and 33.32% saturated. Conclusion: The pulps and seeds of T. catappa have a significantly high content of macro and micronutrients that can meet up the nutritional needs of a population and the quality assessment of the oil suggests that it can be recommended as suitable for industrial usage.

Resistant Rhodococcus for Biodegradation of Diesel Fuel at High Concentration and Low Temperature

The resistance of 16 Rhodococcus strains to diesel fuel was studied. The minimal inhibitory concentrations of diesel fuel against Rhodococcus were 4.0–64.0 vol. % and 0.5–16.0 vol. % after 7 days of incubation in Luria–Bertani broth and a mineral “Rhodococcus-surfactant” medium, respectively. The three most resistant strains (R. ruber IEGM 231, IEGM 442 and Rhodococcus sp. IEGM 1276) capable of overcoming the toxicity of diesel fuel at a high (8.0 vol. %) concentration and at a low (4 °C) temperature were selected. Respiration activities, growth kinetics, and changes in the diesel fuel composition during the biodegradation process were elucidated using gas chromatography with mass spectrometry, respirometry, and Bradford analysis. Growth conditions were optimised for the improved biodegradation of diesel fuel by Rhodococcus cells using multifactor analysis. They included the simultaneous addition of 1.3 g·L−1 of granular sugar and 0.25 g·L−1 of yeast extract. The twofold stimulation of the biodegradation of individual hydrocarbons in diesel fuel (n-pentadecane, n-hexadecane and n-heptadecane) was demonstrated when glycolipid Rhodococcus-biosurfactants were added at a concentration of 1.4 g·L−1. A total removal of 71–91% of diesel fuel was achieved in this work.

Discrimination Among New Vegetative Materials of Passiflora edulis Sims. From Canary Islands by Their Volatile Profile

ABSTRACTThis study shows the successful discrimination among different passion fruit samples cultivated in the Canary Islands, specifically purple, yellow, and a new cultivar labelled as purple selection (obtained to ensure disease resistance, yield, and adequate taste of the cultivated materials), based on their distinctive volatile profile. The headspace solid‐phase microextraction (HS‐SPME) method (using under optimum conditions the commercial CAR/PDMS fibre at 62°C for 60 min and 15% (w/w) NaCl with 10 mL of juices of passion fruit samples) was applied to estimate the volatile profile of up to eighteen passion juice fruit samples, coupling the technique to gas chromatography tandem mass spectrometry (GC–MS). The method permitted the identification of up to 135 volatile compounds such as esters, terpenes and alcohols, among others. The qualitative study indicated that the most abundant compounds in yellow and purple passion fruit are the same (hexyl hexanoate (21%–14%), hexyl butanoate (19%–11%) and ethyl hexanoate (11%–6%)), while the most abundant compounds for this new vegetative material are ethyl octanoate (with almost 53%), hexyl hexanoate and ethyl 3‐hexanoate. Advanced statistical techniques, such as linear discrimination analysis (LDA), were used to explore each data sample, with samples analysed by HS‐SPME‐GC–MS in quadruplicate. 106 peaks were coincident in all chromatograms of the samples, but only 13 variables (compounds) were sufficient to discriminate the new vegetative species. Besides, the HS‐SPME‐GC–MS method proved to be efficient and sustainable, with application of modern metrics of greenness, particularly when compared with other techniques commonly applied for this type of analysis.

Targeted metabolomics investigation of metabolic markers of Mycobacterium tuberculosis in the cerebrospinal fluid of paediatric patients with tuberculous meningitis.

To investigate metabolic markers linked to Mycobacterium tuberculosis (M. tb) in the cerebrospinal fluid (CSF) of a South African cohort of paediatric tuberculous meningitis (TBM). Targeted proton magnetic resonance (1H-NMR) spectroscopy and two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GCxGC-TOFMS) metabolomics approaches were used to evaluate M. tb-linked metabolites in the CSF of 21 definite cases of TBM and 25 control cases. Uni- and multivariate statistical analyses were performed. Four statistically significant metabolites were identified to discriminate TBM cases from controls. Mannose and arabinose were found at lower concentrations in the TBM group. Nonanoic acid and propanoic acid were found in higher concentrations in the definite TBM group. We identified the novel presence of nonanoic acid for the first time as a M. tb-linked marker in the CSF of cases of TBM, possibly as a degradation product of the M. tb cell wall. Propanoic acid can be related to perturbed brain neuro-energetics and neuro-inflammation in TBM cases and is likely a host-response metabolite. Mannose and arabinose-supposed surrogates for lipoarabinomannan, a component of the M. tb cell wall-were not reliable markers for M. tb. Further research should focus on the analysis of fatty acids in the CSF of patients with TBM.

Comparison of Fecal Microbiota and Metabolites Between Captive and Grazing Male Reindeer

The reindeer (Rangifer tarandus) is a circumpolar member of the Cervidae family, and has adapted to a harsh environment. Summer is a critical period for reindeer, with peak digestibility facilitating body fat accumulation. The gut microbiota plays a pivotal role in nutrient metabolism, and is affected by captivity. However, differences in the composition of the gut microbiota and metabolites between captive and grazing reindeer during summer remain poorly understood. Here, we conducted a comparative study of the fecal microbiota and metabolites between captive (n = 6) and grazing (n = 6) male reindeer, using full-length 16S rRNA gene sequencing and gas chromatography–time-of-flight mass spectrometry, respectively. Our results indicated that Prevotella, Phocaeicola, Papillibacter, Muribaculum, and Bacteroides were the predominant genera in the feces of reindeer. However, microbial diversity was significantly higher in captive reindeer compared to their grazing counterparts. Principal coordinate analysis revealed significant differences in the fecal microbiota between captive and grazing reindeer. In captive reindeer, the relative abundances of the genera Clostridium, Paraprevotella, Alistipes, Paludibacter, Lentimicrobium, Paraclostridium, and Anaerovibrio were significantly higher, while those of the genera Prevotella, Phocaeicola, Pseudoflavonifractor, and Lactonifactor were significantly lower. A comparison of predicted functions indicated that pathways involved in fat digestion and absorption, histidine metabolism, lysine biosynthesis, and secondary bile acid biosynthesis were more abundant in captive reindeer, whereas the pathways of fructose and mannose metabolism and propanoate metabolism were less abundant. An untargeted metabolomic analysis revealed that 624 metabolites (e.g., amino acids, lipids, fatty acids, and bile acids) and 645 metabolites (e.g., carbohydrates and purines) were significantly increased in the feces of captive and grazing reindeer, respectively. In conclusion, we unveiled significant differences in fecal microbiota and metabolites between captive and grazing male reindeer, with the results suggesting a potentially enhanced ability to utilize plant fibers in grazing reindeer.

Unveiling the Gold Facet Effect in Selective Oxidation of 5-Hydroxymethylfurfural and Hydrogen Production.

Direct oxidation of 5-hydroxymethylfurfural (HMF) to 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), crucial for medical supply production, is hindered by overoxidation. We synthesized gold nanomaterials with distinct single-crystal facets, {111} in octahedra (OC), {100} in nanocubes (NCs), and {110} in rhombic dodecahedra (RD), to investigate the facet-dependent HMF oxidation. The Au RD achieved the spontaneous oxidation of HMF to HMFCA with stoichiometric hydrogen production, maintaining 95% carbon balance, 91% yield, and 98% selectivity. In contrast, Au OC and NCs were inert. The superior performance is due to the absence of a C-H activation energy barrier on the Au(110) facet. Furthermore, gas chromatography and isotope experiments supported that the intermediate is oxidized to produce H2 via H- transfer, rather than H2O via H+ transfer. Oxygen was essential for scavenging electrons, thereby closing the reaction loop. The Au RD exhibited remarkable stability, operating for 240 h without performance degradation, indicating its potential for efficient HMFCA production.

Assessment of Characteristic Flavor and Taste Quality of Sugarcane Wine Fermented with Different Cultivars of Sugarcane

In order to explore the variation in volatile compounds and aroma profiles of different varieties of sugarcane wine, volatile compounds of 14 different varieties of sugarcane wine were analyzed by headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS) and an electronic sensory system. The differences in flavor substances of different cultivars of sugarcane were assessed by orthogonal partial least squares discriminant analysis (OPLS-DA) discriminant model and relative odor activity value (ROAV) combined with multivariate statistical methods. The results showed that a total of sixty major volatile compounds, i.e., 27 esters, 15 alcohols, eight acids, three phenols, four aldehydes and ketones, and four others, were identified in 14 types of sugarcane wine. Seven key aroma compounds were screened out: ethyl caprylate, ethyl caprate, ethyl acetate, ethyl laurate, n-decanoic acid, 2,4-di-tert-butylphenol, and 2-phenylethanol and three differential aromas, i.e., ethyl palmitate, isobutyl alcohol, and caprylic acid. The electronic nose and electronic tongue analysis technology can effectively distinguish the aroma and taste of 14 sugarcane wines. It is confirmed that the aroma and taste of 14 sugarcane wines have differences in distribution patterns, and the results are consistent with the analysis and assessment of volatile compounds of sugarcane wine. The results of this study provide technical support for the production and quality improvement of sugarcane wine.