Gas Chromatography Research Articles

Feedback control of an experimental electrically-heated steam methane reformer

Steam methane reforming (SMR) is the most common industrial process to produce hydrogen (H2) from methane and water vapor. The SMR reactions are overall highly endothermic and traditionally, fossil fuels are burned to provide the necessary heat of reaction. However, it was found that electrifying the tubular SMR reactors using renewable electrons instead of conventional heating gives the opportunity of producing H2 with lower carbon emissions, lower reactor volumes, and higher carbon conversion. While current studies in this new technology focus on improving the catalysts or heating sources, a more efficient process control scheme can also significantly contribute to the understanding of potential challenges and opportunities of combining renewables and natural gas in the production of H2 at industrial scales. In order to further develop the electrically-heated SMR process and the associated control strategies, we have constructed an experimental Joule-heated SMR system at UCLA. The system contains a tubular reactor with a washcoated Ni/ZrO2 catalyst, two thermocouples connected to the top and bottom of the reactor, a power supply for providing electrical heating, and an on-line gas chromatograph (GC) for measuring outlet gas concentrations. The synthesis procedure of the catalyst, SMR data collection, and thermal considerations for catalyst degradation are described in this paper and are all accounted for experimentally when using a proportional integral (PI) controller to gradually increase the reactor temperature without harming the catalyst. Advanced control strategies, such as model predictive control (MPC), require a process model that uses measurement feedback to make predictions of the process time-evolution in order to optimize the control actions in real-time. We have previously developed a lumped-parameter modeling strategy for the SMR process. The MPC objective is to control the H2 production rate by manipulating the current flowing through the outer reactor shell. However, to use this model in an MPC, feedback values for all state variables should be provided by the sensors. In our experimental system, the on-line GC only gives discrete measurements with a long sampling period. To this end, the process model is incorporated into an extended Luenberger observer (ELO) that uses the reactor temperature and GC measurements to provide estimates of all the variables needed by the MPC. The ELO-based MPC system is then experimentally implemented on the process and it is demonstrated to be more efficient in terms of speed of the closed-loop response than the PI controller using delayed, measurement feedback by the GC.

Differential metabolite analysis of the pharmacodynamic differences between different ratios of Dahuang ()-Taoren () herb pair.

To explore the material basis of the difference of efficacy of Dahuang (Radix Et Rhizoma Rhei Palmati)-Taoren (Semen Persicae) (DT) drugs with different proportions. Samples of different ratios of Dahuang (Radix et Rhizoma Rhei Palnati, DH) to Taoren (Semen Persicae, TR) (Group A 1:1, B 2:3, C 3:2) were analyzed based on gas chromatography time-of-flight mass spectrometry untargeted metabolomics technique. A total of 240 primary metabolites were detected. Forty-one differential metabolites involved nine differential metabolic pathways, of which four were closely related to the efficacy of DT in the treatment of heat and blood stasis syndrome. These pathways included the biosynthesis of amino acid (phenylalanine tyrosine and tryptophan), flavonoids, unsaturated fatty acids, and the glycolysis/glycogenesis pathway. There are significant differences in the efficacy of different ratios of DT drugs, and their optimal ratio for the treatment of heat and blood stasis syndrome should be 1:1.

Characterization of industrial TNT in ammunition shells: An in-depth study of artificial aging effects using Fourier-Transform infrared spectroscopy and gas chromatography–mass spectrometry

In this study, we comprehensively investigated the degradation of industrial trinitrotoluene (TNT), focusing on the effects of aging and direct contact with steel surfaces, mirroring real-world usage conditions. While practical knowledge exists regarding this degradation, the existing literature lacks in-depth insights into the underlying processes. To address this gap, we conducted experiments using small steel samples, representative of military ammunition casings, which were coated with TNT and subjected to 30 days of heating at 75 °C under vacuum conditions. A subset of these samples was coated with a protective red alkyd paint. After the aging process, the TNT was carefully removed from the metal surfaces and subjected to a comprehensive analysis encompassing scanning electron microscopy, Fourier-transform infrared spectroscopy, and gas chromatography-mass spectrometry. Our results reveal a remarkable preservation of the chemical integrity of industrial TNT, even in the presence of thermal stress and direct steel contact. Although superficial changes were observed in the TNT's appearance, all analytical data consistently demonstrated the maintenance of its chemical composition. Notably, the sole change in composition was attributed to the presence of degradation products associated with the alkyd paint coating, rather than intrinsic TNT degradation. These findings underscore the negligible impact of degradation processes on TNT in scenarios involving the solid-phase thermal stress of TNT in direct contact with metal, significantly enhancing our understanding of TNT safety when packaged within steel artifacts—a common context in military ammunition.

Short-term exposures to PM2.5, PM2.5 chemical components, and antenatal depression: Exploring the mediating roles of gut microbiota and fecal short-chain fatty acids

BACKGROUNDPM2.5 and its chemical components increase health risks and are associated with depression and gut microbiota. However, there is still limited evidence on whether gut microbiota and short-chain fatty acids (SCFAs) mediate the association between PM2.5, PM2.5 chemical components, and antenatal depression. The purpose of this study was to investigate the mediating role of maternal gut microbiota in correlations between short-term exposure to PM2.5, short-term exposure to PM2.5 chemical components, and antenatal depression. METHODSDemographic information and stool samples were collected from 75 pregnant women in their third trimester. Their exposure to PM2.5 and PM2.5 chemical components was measured. Participants were divided into the non-antenatal depression group or the antenatal depression group according to the cut-off of 10 points on the Edinburgh Postnatal Depression Scale (EPDS). The gut microbiota were analyzed using the 16S rRNA-V3/V4 gene sequence, and the concentration of PM2.5 and its chemical components was calculated using the Tracking Air Pollution in China (TAP) database. Gas chromatography–mass spectrometry was used to analyze SCFAs in stool samples. In order to assess the mediating effects of gut microbiota and SCFAs, mediation models were utilized. RESULTSThere were significant differences between gut microbial composition and SCFAs concentrations between the non-antenatal depression group and the antenatal depression group. PM2.5 and its chemical components were positively associated with EPDS scores and negatively associated with genera Enterococcus and Enterobacter. Genera Candidatus_Soleaferrea (β = -7.21, 95%CI -11.00 to -3.43, q = 0.01) and Enterococcus (β = -2.37, 95%CI -3.87 to -0.87, q = 0.02) were negatively associated with EPDS scores, indicating their potential protective effects against antenatal depression. There was no significant association between SCFAs and EPDS scores. The mediating role of Enterococcus between different lagged periods of PM2.5, PM2.5 chemical component exposure, and antenatal depression was revealed. For instance, Enterococcus explained 29.23% (95%CI 2.16% to 87.13%, p = 0.04) of associations between PM2.5 exposure level at the day of sampling (lag 0) and EPDS scores. CONCLUSIONOur study highlights that Enterococcus may mediate the associations between PM2.5, PM2.5 chemical components, and antenatal depression. The mediating mechanism through which the gut microbiota influences PM2.5-induced depression in pregnant women still needs to be further studied.

Investigation of the Molecular Mechanism Underlying the Therapeutic Effect of Perilla frutescens L. Essential Oil on Acute Lung Injury Using Gas Chromatography Mass Spectrometry and Network Pharmacology.

The present study aimed to investigate the molecular mechanism through which Perilla essential oil treats acute lung injury (ALI) through network pharmacology, molecular docking, and in vitro assays. Relevant ALI targets of the active ingredients of Perilla essential oil were predicted using the SwissTargetPrediction database and meta TarFisher database. These ALI targets were then screened using GeneCards and DisGeNET, and differentially expressed ALI target genes were identified using the Gene Expression Omnibus (GEO) database. Next, key targets were enriched using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Protein-protein interaction network analysis was performed to obtain targets with the highest degree values for molecular docking with Perilla essential oil active ingredients. For in vitro experiments, lipopolysaccharide (LPS) was used to induce an ALI inflammation model using RAW264.7 cells. The model cells were then treated with Perilla essential oil to detect the protein expression levels of vascular endothelial factor (NO), tumor necrosis factor (TNF-α), and p65 nuclear transcription factor in them. Sixty-eight key targets of Perilla oil were identified for the treatment of ALI. These targets were found to be involved in biological processes related to peptides, response to lipopolysaccharides, the positive regulation of cytokine production, etc., using GO. The signaling pathways found to be associated with the targets included the AGE-RAGE signaling pathway in diabetic complications, the NF-kappa B signaling pathway, and small cell lung cancer and other inflammatory signaling pathways. The five key targets that showed good binding activity with Perilla oil active ingredients included TNF, RELA, PARP1, PTGS2, and IRAK4. In vitro assays showed that Perilla essential oil could significantly reduce NO and TNF-α levels and inhibit the phosphorylation of nuclear transcription factor P65, thus inhibiting the activation of NF-κB signaling pathway. Conclusion Perilla essential oil can play a role in the treatment of ALI by inhibiting the activation of the NF-κB signaling pathway and preventing an excessive inflammatory response. This study thus provides a reference for the in-depth study of the mechanisms through which Perilla essential oil treats ALI.

Environmentally Friendly Processing of Forestry Biomass Side Streams – Coniferous Needles and Greenery

Replacement of fossil materials with renewable biomass is essential to address climate change challenges and implement bioeconomy as essential element of sustainable development model. A significant source of biomass is forestry, however besides timber significant amounts of forestry biomass side streams are formed and from circular bioeconomy perspective full utilisation of valuable resources is requested. One of side products of coniferous tree processing are needles and greenery and as these trees are dominant in Northern regions full use of their biomass can provide significant input to replace fossil resource-based substances and materials. Coniferous tree needles and greenery are a rich source of biologically active substances with wide application potential as resource for biopharma industries, for food and feed supplements and materials for diverse application. Traditionally for extraction of biologically active substances from coniferous needles and greenery toxic and hazardous solvents, such as organochlorine and hydrocarbon solvents has been used. The aim of the present study is to develop possibilities to use green chemistry approaches for coniferous needle and greenery extraction and following biorefinery to obtain biologically active components. For extraction of coniferous needle and greenery green solvents has been tested as well as so called intensive extraction methos has been used. The yield of extracts depends on extraction temperature, duration, solvent and other factors and optimal extraction conditions provide possibilities to obtain yield of extracts higher that use of traditionally used solvents. As a powerful tool to increase yields of extracts so called intensive extraction methods, such as treatment with ultrasound, microwaves, accelerated solvent extraction has been studied. The obtained extracts were characterised using gas chromatography with mass spectrometric detection, liquid chromatography and other methods. Possibilities of biorefinery of obtained extracts to isolate groups of substances or individual substances has been discussed.

PH-Optimized Biomethane Production: Evaluating Carrier Materials for Ex-situ Biomethanation

Choosing the appropriate carrier material for ex-situ biomethanation is a critical factor to consider when developing biogas upgrading technologies. The chosen material for biomethanation in a biotrickling filter reactor functions as a substrate that immobilises microorganisms, which act as catalysts in the reaction for producing biomethane. This study conducted experiments on waste-derived materials, including glass foam and vulcanised wood ash material, in addition to polyurethane foam and expanded clay pellets. Pretreratment of wood ash was done to lower the pH of material. The manometric test measured the rate of CH4 generation by quantifying pressure fluctuations. The validity of these results was confirmed by analysing product gas samples using a Shimadzu Nexis GC-2030 gas chromatograph, which was equipped with two parallel lines, a flame ionisation detector (FID) and a thermal conductivity detector (TCD). In order to enhance the biomethane concentration in the end product, two strains of Methanobacterium alcaliphilum were evaluated alongside biogas sludge as the inoculum. These strains of microorganisms are methanogens that utilise hydrogen and can thrive in a high pH environment. Thus, they have the potential to demonstrate improved biomethane production outcomes when a vulcanised wood ash filter is used as the carrier material.

Microwave-Assisted “One-Pot” Acidolysis and Extraction for the Rapid Determination of Mancozeb in Fruit and Vegetable Samples

Mancozeb is an extensively consumed fungicide, which often leaves high residue levels on agricultural products. The conventional method for detecting mancozeb involves a time-consuming process using gas chromatography (GC) after a 2-hour water-bath acidolysis, resulting in low efficiency and recovery rates. This study developed a rapid method for detecting mancozeb in fruits and vegetables using microwave-assisted acidolysis and extraction coupled with GC analysis. Mancozeb underwent “one-pot” acidolysis to generate CS2 gas and was subsequently extracted from samples using microwave treatment, requiring only 50 seconds of pretreatment time. The average recoveries of mancozeb ranged from 81% to 112%. The limit of detection and limit of quantification were 0.003 and 0.01 mg kg−1, respectively. The scanning electron microscope imaging showed that strong cell crumpling after microwave treatment improved the acidolysis rate significantly, where the acidolysis rate was 91.8% for mancozeb. In addition, this method is rapid, simple, and precise for detecting residues of mancozeb and other dithiocarbamate fungicides.

Urine as Biobased Fertilizer: The Netherlands as Case Study

Humankind has grown ever more dependent on mineral fertilizer to feed a growing world population. However, nutrients are rarely recovered and recycled after consumption, leading to environmental waste issues now and potential supply issues in the future. Urine is rich in these nutrients and therefore a prime candidate as precursor for biobased fertilizers. This work presents a case study to remove contaminants – predominantly pharmaceuticals – from human urine using activated carbon adsorbents in an effort to adhere to Dutch fertilizer legislation. In the urine, three pharmaceuticals were identified by target analysis and 11 other contaminants by suspect screening using liquid chromatography quadrupole time of flight mass spectrometry (LC-QTOF/MS). These were successfully removed by treatments with both granulated and powdered activated carbon, albeit with a loss of 16-17% and 2-4% of dissolved nutrients, respectively. Further screening of inorganic contaminants and persistent organic pollutants by inductively coupled plasma mass spectrometry (ICP-MS) and gas chromatography quadrupole-orbitrap mass spectrometry (GC-Q-Orbitrap/MS) showed that all prerequisites for fertilizer status are met, paving the way for its future legal use as biobased fertilizer in the Netherlands.

Density-mediated foraging behavioral responses of Rhyzopertha dominica (Coleoptera: Bostrichidae) and Tribolium castaneum (Coleoptera: Tenebrionidae)

Tribolium castaneum and Rhyzopertha dominica are cosmopolitan, destructive postharvest pests. Although research has investigated how high densities of T. castaneum affect attraction to the aggregation pheromone by conspecifics, research into the behavioral response of both species to food cues after high density exposure has been lacking despite its importance to foraging ecology. Our goal was to manipulate and observe the effects of crowding on the behavioral response of both species to common food and pheromonal stimuli and to determine how the headspace emission patterns from grain differed under increasing densities. Densities of colonies for both species was altered (10–500 adults) on a fixed quantity of food (10 g of flour or whole wheat), then the behavioral response to common food and pheromonal cues was evaluated in a wind tunnel and release-recapture experiment, while volatiles were examined through gas chromatography coupled with mass spectrometry. Importantly, at least for T. castaneum, crowded conditions attenuate attraction to food-based stimuli, but not pheromonal stimuli. Crowding seemed to have no effect on R. dominica attraction to food and pheromonal stimuli in the wind tunnel, but exposure to high density cues did elicit 2.1–3.8-fold higher captures in traps. The relative composition and abundance of headspace volatiles emitted varied significantly with different densities of beetles and was also species-specific. Overall, our results have implications for expanding our understanding of the foraging ecology of two economically important pests.

Characterization of Key Odor-Active Compounds in Draft Beers for the Chinese Market Using Molecular Sensory Science Approaches

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

Determination of chloropropanol esters and glycidyl esters in nutritional foods by gas chromatography–tandem mass spectrometry based on acid hydrolysis and solid-phase extraction

This study presents a method based on acid transesterification and the purification by solid-phase extraction (SPE) coupled with gas chromatography–tandem mass spectrometry for quantifying 3- and 2-monochloropropanediol esters (3-MCPDE, 2-MCPDE) and glycidyl esters (GE) in nutritional foods. The fat was extracted by liquid–liquid extraction with petroleum ether and diethyl ether after the sample was hydrolysed with ammonia. Then the extract was purified by a SPE cartridge filled with the aminopropyl sorbents. It was demonstrated that the optimal elution volume for 3-MCPDE, 2-MCPDE and GE greatly depended on the sample matrix and varied from 6 to 12 mL for four different kinds of food matrices. All three analytes in the sample solution could be fully collected in the first 10–12 mL of eluate. By this way, monoacylglycerols commonly present in the samples were fully removed. Therefore, the overestimation of GE quantification was effectively eliminated. The modified analytical procedure was fully validated in a single laboratory and has been recommended as a Chinese Food Safety National Standard. In addition, two derivatisation agents, heptafluorobutyrylimidazole and phenylboronic acid, were proved to be equivalent in method accuracy and precision for the quantification of three analytes.

An extended Monte Carlo simulation code for modeling gas chromatography experiments with superheavy elements and their homologs

AbstractMonte Carlo simulations are commonly used to model the behavior of chemical species of the heaviest elements and their homologs in gas chromatography experiments. In this paper, we present an extension of the fundamental Monte Carlo simulation proposed by Zvara in 1985. While preserving the core functionality, our code features two enhancements: first, it allows simulating experiments in which a primary radioisotope decays into a daughter isotope belonging to a different element, hence exhibiting different chemical properties. Second, it allows modeling scenarios where conversion of an initial chemical species to a different one can occur at temperatures high enough to overcome an activation barrier, facilitating simulations of related physisorption and chemisorption processes. This Monte Carlo code is applicable to open tubular and rectangular chromatography columns.

Seasonal influence on the essential oil chemical composition of Hyptis crenata Pohl ex Benth.: a valuable plant from Marajó, Brazil

Introduction: Essential oils (EOs) from the Hyptis genus have been reported as bactericides and fungicides. However, the properties of these oils can be affected by climatic factors, as well as the collection period, which promotes changes in the chemical composition of the oil. In this context, this study aimed to evaluate the climatological influences on the chemical composition of the essential oil from the leaves of Hyptis crenata.Methods: The leaves were collected in Marajó island (Brazil) monthly for a year. The EOs were obtained by hydrodistillation and analyzed by Gas Chromatography coupled to Mass Spectrometry (GC-MS). Pearson’s correlation was used to evaluate the relationship between climatic parameters, content, and chemical composition of essential oil; multivariate analysis was used to evaluate the interrelationship between samples and their chemical constituents.Results and Discussion: The constituents with the highest contents (>2.0%) in essential oils during the studied period were 1,8-cineole (28.48% ± 4.32%), α-pinene (19.58% ± 2.29%), camphor (11.98% ± 2.54%), β-pinene (9.19% ± 1.47%), limonene (6.12% ± 3.15%), α-terpineol (2.42% ± 0.25%) and borneol (2.34% ± 0.48%). β-Pinene significantly correlated (p < 0.05) with precipitation and humidity. According to the chemometric tools, two groups were formed: chemical profile I, marked by 1,8 cineole, α-pinene, β-pinene, borneol, α-terpineol, and limonene, while group II (July) presented a chemical type characterized by camphor. It is understood that the species in question can be a reliable source of biologically active components during different climatic periods in the Amazon. The chemical variability could have significant implications for the pharmaceutical industry and traditional medicine.

Assessment of artificial intelligence to detect gasoline in fire debris using HS-SPME-GC/MS and transfer learning.

Due to the complex nature of the chemical compositions of ignitable liquids (IL) and the interferences from fire debris matrices, interpreting chromatographic data poses challenges to analysts. In this work, artificial intelligence (AI) was developed by transfer learning in a convolutional neural network (CNN), GoogLeNet. The image classification AI was fine-tuned to create intelligent classification systems to discriminate samples containing gasoline residues from burned substrates. All ground truth samples were analyzed by headspace solid-phase microextraction (HS-SPME) coupled with a gas chromatograph and mass spectrometer (GC/MS). The HS-SPME-GC/MS data were transformed into three types of image presentations, that is, heatmaps, extracted ion heatmaps, and total ion chromatograms. The abundance and mass-to-charge ratios of each scan were converted into image patterns that are characteristic of the chemical profiles of gasoline. The transfer learning data were labeled as "gasoline present" and "gasoline absent" classes. The assessment results demonstrated that all AI models achieved 100 ± 0% accuracy in identifying neat gasoline. When the models were assessed using the spiked samples, the AI model developed using the extracted ion heatmap obtained the highest accuracy rate (95.9 ± 0.4%), which was greater than those obtained by other machine learning models, ranging from 17.3 ± 0.7% to 78.7 ± 0.7%. The proposed work demonstrated that the heatmaps created from GC/MS data can represent chemical features from the samples. Additionally, the pretrained CNN models are readily available in the transfer learning workflow to develop AI for GC/MS data interpretation in fire debris analysis.

FeCo‐oxalate Organic Framework as an Efficient Electrocatalyst for Oxygen Evolution Reaction

Developing nonprecious metallic electrocatalysts for water splitting is of vital importance for sustainable environment and energy technologies. As for oxygen evolution reaction (OER), FeCo‐based bimetallic catalysts have been found to act as promising candidates owing to their high intrinsic activity. Herein, a novel FeCo‐oxalate organic framework was grown on nickel foam (FeCo‐OA@NF) under mild conditions. The optimized electrocatalyst shows good OER performance with a low overpotential of 275 mV at the current density of 100 mA cm−2 in alkaline environment, comparable to that of commercial Ru‐based catalyst. Moreover, the quantification of produced oxygen by both gas chromatography and drainage method demonstrates nearly 100% Faradaic efficiency. Except for the contribution of Fe and Co species for the excellent OER catalytic activity, in‐situ Raman spectroscopy reveals that the positive effect of oxalate coordination also makes a difference, which can possibly reduce electron transport resistance and provide more active sites. This work provides a promising approach for the preparation of alkaline oxygen evolution electrocatalysts with low‐cost and high performance.

Assessment of Moroccan Cannabis sativa Seed Oil: Chemical Analysis and Evaluation of Antioxidant, Toxicological, and Antinociceptive Effects.

Cannabis sativa L. is a plant known locally as "El kif" of the Cannabaceae family. This study aimed to conduct a chemical analysis of Cannabis sativa seed oil (CSSO) and assess its acute toxicity, antioxidant properties, and analgesic effects. The chemical analysis was performed using gas chromatography and mass spectrometry (GC/MS) to identify its fatty acids (FAs) content. Antioxidant activity was evaluated in vitro using the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging method and the FRAP (ferric reducing antioxidant power) method. Concurrently, acute toxicity, along with antinociceptive activity, was studied through three distinct animal models: writhing test, formalin test, and hot plate test. The results revealed that linoleic acid, oleic acid, α-linolenic acid, and palmitic acid were the main components of CSSO. The LD50 of CSSO was greater than 5 g/kg, indicating low toxicity. Additionally, CSSO exhibited a significant content of flavonoids and total polyphenols, along with notable antioxidant activity with values. The results indicated a significant increase in thermal stimulus latency, a reduction in the number of writhes induced by acetic acid, and a decrease in licking time in both phases of the formalin test. In conclusion, this study suggests promising results for CSSO emphasizing its potential as a therapeutic agent.

Simultaneous quantification of terpenes and cannabinoids by reversed-phase LC-APCI-MS/MS in Cannabis sativa L. samples combined with a subsequent chemometric analysis.

Cannabis sativa L. has been the most discussed medicinal plant in recent years. In particular, the dynamic shift from a formerly illicit and tightly controlled substance to a plant recognized for both medicinal and recreational purposes has brought C. sativa into the global spotlight. Due to the ongoing international legalization processes, fast and convenient analytical methods for the quality control of C. sativa flowers for medicinal and recreational purposes are of tremendous interest. In this study, we report the development and validation of a liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method applying atmospheric pressure chemical ionization (APCI) to fully quantify 16 terpenes and 7 cannabinoids including their acidic forms by a single chromatographic method. The method presented here is unique and simple, as it eliminates the need for derivatization reactions and includes the unconventional analysis of volatile compounds by liquid chromatography. Samples were prepared by a simple and fast ethanolic extraction. Separation was accomplished within 25min on a reversed-phase C18 column. Method validation was conducted according to international guidelines regarding selectivity, accuracy, precision, robustness, and linearity. Detection was done in multiple reaction monitoring, which allowed the simultaneous quantification of co-eluting analytes applying two selective mass transitions. In addition, due to reproducible in-source decarboxylation, the acidic forms of cannabinoids were reliably quantified using mass transitions of the neutral forms. The accuracy given as the bias was below 15% for all analytes. Matrix effects for cannabinoids were studied by spiking Humulus lupulus extracts with the analytes at varying concentrations. APCI did not show susceptibility toward ion suppression or enhancement. In addition, the recovery effect after spiking was between 80 and 120% for terpenes. Further, 55 authentic C. sativa extracts were fully quantified, and the obtained results for the terpene profiles were compared to state-of-the-art gas chromatography coupled to flame ionization detection. Comparable results were achieved, emphasizing the method's applicability for cannabinoids and terpenes. Further, acquired metabolite patterns for C. sativa samples were studied, identifying a relationship between cannabinoid and terpene patterns, as well as the abundance of myrcene in CBD-dominant C. sativa strains.

The Influence of Cooking Methods and Muscle on Beef Aroma Profile and Consumer Satisfaction: Insights from Volatile Compound Analysis

The objective of this study is to determine the effect of two distinct cooking techniques, namely roasting and stewing, on the formation of volatile compounds in various beef muscles (Semimembranosus, Biceps femoris, and Rectus femoris) and how this relates to consumer acceptance. The research employs the concept of volatile “marker” compounds to discern the influence of cooking techniques on the flavor profile of beef. Eighteen “marker compounds” were selected to represent a number of the mechanisms of formation and quantified in beef subjected to two different cooking methods. While no statistically significant differences were observed in consumer evaluations between the two cooking methods, notable disparities emerged in the consumer assessments of specific muscle cuts. Notably, the Rectus femoris muscle received the highest ratings (p < 0.05) among other evaluated muscles. The utilization of Solid-Phase Microextraction (SPME) and gas chromatography–mass spectrometry (GC-MS) methods for the analysis of volatile “marker compounds” in beef proved effective in highlighting significant differences in flavor compound classes between cooking methods, and these differed between muscles. The main effect was of the cooking method with stewed beef aroma having approximately 39× more dimethyl trisulphide, 9× more dimethyl disulphide, 7× more pentanal, 3× more hexanal, and twice as much benzaldehyde and 2-methylthiophene. Dimethyldisulphide, dimethyltrisulphide, hexanal, and heptanal, therefore, emerged as characteristic volatile compounds associated with the stewing cooking technique, suggesting their potential as markers for lipid and other oxidation reactions. This work indicates that certain lipid oxidation compounds, Strecker aldehydes, and sulfur compounds can be markers for the undesirable and/or desirable flavors of cooked beef, but that this depends on the cooking method chosen. It shows that flavor differences may be understood through the analysis of volatile flavor compounds in association with palatability and other chemical measurements.

Natural Extracts and Essential Oils as Ingredients in Cosmetics: Search for Potential Phytomarkers and Allergen Survey

The increasing use of natural ingredients such as essential oils (EOs) and natural extracts (NEs) in cosmetics is an analytical and legislative challenge due to their complex composition, which includes recognized allergenic compounds. In this work, 17 EOs and NEs have been characterized by gas chromatography coupled to mass spectrometry (GC-MS) of dilutions of the original samples. Additionally, solid phase microextraction (SPME) was applied for the analysis of volatile components. The results obtained allowed the identification of more than 90 compounds, including 20 allergens, in the analyzed samples and the study of potential phytomarkers of the addition of EOs and ENs in cosmetics.