Lipidomic and Fatty Acid Biomarkers in Whole Blood Can Predict the Dietary Intake of Eicosapentaenoic and Docosahexaenoic Acidsin a Danish Population

BACKGROUND

The intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been associated with health benefits. Blood levels of these fatty acids, measured by gas chromatography (GC), are associated with their dietary intake, but the relationships with lipidomic measurements are not well defined.

OBJECTIVES

This study aimed to determine the lipidomic biomarkers in whole blood that predict intakes of EPA + DHA and examine the relationship between lipidomic and GC-based n-3 polyunsaturated fatty acid (n-3 PUFA) biomarkers.

METHODS

Lipidomic and fatty acid analyses were completed on 120 whole blood samples collected from Danish participants. Dietary intakes were completed using a web-based 7-d food diary. Stepwise multiple linear regression was used to identify the fatty acid and lipidomic variables that predict intakes of EPA + DHA and to determine lipidomic species that predict commonly used fatty acid biomarkers.

RESULTS

Stepwise regression selected lipidomic variables with an R2 = 0.52 for predicting EPA + DHA intake compared to R2 = 0.40 for the selected fatty acid GC-based variables. More predictive models were generated when the lipidomic variables were selected for females only (R2 = 0.62, n = 68) and males only (R2 = 0.72, n = 52). Phosphatidylethanolamine plasmalogen species containing EPA or DHA tended to be the most predictive lipidomic variables. Stepwise regression also indicated that selected lipidomic variables can predict commonly used fatty acid GC-based n-3 PUFA biomarkers as the R2 values ranged from 0.84 to 0.91.

CONCLUSIONS

Both fatty acid and lipidomic data can be used to predict EPA + DHA intakes, and fatty acid GC-based biomarkers can be emulated by lipidomic species. Lipidomic-based biomarkers appear to be influenced by sex differences, probably in n-3 PUFA and lipoprotein metabolism. These results improve our ability to understand the relationship between novel lipidomic data and GC fatty acid data and will increase our ability to apply lipidomic methods to fatty acid and lipid nutritional research.

A closer look at high-energy X-ray-induced bubble formation during soft tissue imaging

Improving the scalability of tissue imaging throughput with bright, coherent X-rays requires identifying and mitigating artifacts resulting from the interactions between X-rays and matter. At synchrotron sources, long-term imaging of soft tissues in solution can result in gas bubble formation or cavitation, which dramatically compromises image quality and integrity of the samples. By combining in-line phase-contrast imaging with gas chromatography in real time, we were able to track the onset and evolution of high-energy X-ray-induced gas bubbles in ethanol-embedded soft tissue samples for tens of minutes (two to three times the typical scan times). We demonstrate quantitatively that vacuum degassing of the sample during preparation can significantly delay bubble formation, offering up to a twofold improvement in dose tolerance, depending on the tissue type. However, once nucleated, bubble growth is faster in degassed than undegassed samples, indicating their distinct metastable states at bubble onset. Gas chromatography analysis shows increased solvent vaporization concurrent with bubble formation, yet the quantities of dissolved gasses remain unchanged. By coupling features extracted from the radiographs with computational analysis of bubble characteristics, we uncover dose-controlled kinetics and nucleation site-specific growth. These hallmark signatures provide quantitative constraints on the driving mechanisms of bubble formation and growth. Overall, the observations highlight bubble formation as a critical yet often overlooked hurdle in upscaling X-ray imaging for biological tissues and soft materials and we offer an empirical foundation for their understanding and imaging protocol optimization. More importantly, our approaches establish a top-down scheme to decipher the complex, multiscale radiation-matter interactions in these applications.

A high performance thin layer chromatography (HPTLC) method for the quality assessment of agarwood (Aquilaria malaccensis) oil from Northeast India

The high-value agarwood oil, largely used in perfumery is generally graded by the traditional method of sensorial assessment. The compositional complexity and variation made its quality control challenging. Besides, non-volatile contaminants and adulterants are the bottlenecks in gas-chromatographic detection. Herein, a HPTLC based technique was developed for the quality assessment of agarwood oil from Northeast India. A 'marker band' (anisylacetone and oxygenated sesquiterpene rich) on HPTLC profile, containing major peaks of the oil and characteristic agarwood aroma was quantified to assess the quality. The developed method was validated in terms of specificity, linearity, sensitivity, recovery and precision. The application of the method in test samples of three different grades indicated a positive correlation between 'marker band' quantity and oil quality. Its abundance in the superior grade oil was >50% and <20% in poor grade. It can be an efficient analytical tool for the quality assessment and grading of agarwood oil.

What is the role of current mass spectrometry in pharmaceutical analysis?

The role of mass spectrometry (MS) has become more important in most application domains in recent years. Pharmaceutical analysis is specific due to its stringent regulation procedures, the need for good laboratory/manufacturing practices, and a large number of routine quality control analyses to be carried out. The role of MS is, therefore, very different throughout the whole drug development cycle. While it dominates within the drug discovery and development phase, in routine quality control, the role of MS is minor and indispensable only for selected applications. Moreover, its role is very different in the case of analysis of small molecule pharmaceuticals and biopharmaceuticals. Our review explains the role of current MS in the analysis of both small-molecule chemical drugs and biopharmaceuticals. Important features of MS-based technologies being implemented, method requirements, and related challenges are discussed. The differences in analytical procedures for small molecule pharmaceuticals and biopharmaceuticals are pointed out. While a single method or a small set of methods is usually sufficient for quality control in the case of small molecule pharmaceuticals and MS is often not indispensable, a large panel of methods including extensive use of MS must be used for quality control of biopharmaceuticals. Finally, expected development and future trends are outlined.

Construction of Hierarchical Porous UiO-66-Br2@PS/DVB-Packed Columns by High Internal Phase Emulsion Strategy for Enhanced Separation of CF4/N2 and SF6/N2

Recovery and separation of anthropogenic emissions of electronic specialty gases (F-gases, such as CF4 and SF6) from the semiconductor sector are of critical importance. In this work, the hierarchical porous UiO-66-Br2@PS/DVB-packed column was constructed by a high internal phase emulsions strategy. UiO-66-Br2@PS/DVB exhibits a superior selectivity of CF4/N2 (2.67) and SF6/N2 (3.34) predicted by the IAST due to the diffusion limitation in the micropore and the gas-framework affinity. Especially, UiO-66-Br2@PS/DVB showed significant CF4 and SF6 retention and enabled the successful separation of CF4/N2 and SF6/N2 with a resolution of 2.37 and 8.89, respectively, when used as a packed column in gas chromatography. Compared with the Porapak Q column, the HETP of the UiO-66-Br2@PS/DVB-packed column decreased and showed good reproducibility. This research not only offers a convenient method for fabricating a hierarchical porous MOF-packed column but also showcases the prospective utilization of MOFs for the separation of the F-gas/N2 mixture.

Effect of Mechanical Damage in Green-Making Process on Aroma of Rougui Tea

Rougui Tea (RGT) is a typical Wuyi Rock Tea (WRT) that is favored by consumers for its rich taste and varied aroma. The aroma of RGT is greatly affected by the process of green-making, but its mechanism is not clear. Therefore, in this study, fresh leaves of RGT in spring were picked, and green-making (including shaking and spreading) and spreading (unshaken) were, respectively, applied after sun withering. Then, they were analyzed by GC-TOF-MS, which showed that the abundance of volatile compounds with flowery and fruity aromas, such as nerolidol, jasmine lactone, jasmone, indole, hexyl hexanoate, (E)-3-hexenyl butyrate and 1-hexyl acetate, in green-making leaves, was significantly higher than that in spreading leaves. Transcriptomic and proteomic studies showed that long-term mechanical injury and dehydration could activate the upregulated expression of genes related to the formation pathways of the aroma, but the regulation of protein expression was not completely consistent. Mechanical injury in the process of green-making was more conducive to the positive regulation of the allene oxide synthase (AOS) branch of the α-linolenic acid metabolism pathway, followed by the mevalonate (MVA) pathway of terpenoid backbone biosynthesis, thus promoting the synthesis of jasmonic acid derivatives and sesquiterpene products. Protein interaction analysis revealed that the key proteins of the synthesis pathway of jasmonic acid derivatives were acyl-CoA oxidase (ACX), enoyl-CoA hydratase (MFP2), OPC-8:0 CoA ligase 1 (OPCL1) and so on. This study provides a theoretical basis for the further explanation of the formation mechanism of the aroma substances in WRT during the manufacturing process.

Residues determination, risk assessment, and dissipation behavior of myclobutanil formulation on apple

This study aimed to investigate the dissipation pattern, risk assessment, and waiting period of myclobutanil on apple fruit (Malus domestica Borkh.) under temperate conditions in Kashmir, India. The study involved the application of myclobutanil 10 WP at a single recommended dosage (125 g a.i. ha-1) and double dosage (250 g a.i. ha-1) on Red Velox apple trees, 2 months before harvest. GC equipped with an electron capture detector was used to analyze myclobutanil residues in fruit samples. The study revealed that myclobutanil, at both recommended and double recommended doses, dissipated rapidly and became nondetectable after 55 and 60 days, respectively. The waiting period for myclobutanil application was determined to be 12.41 days for the single dose and 25.58 days for the double dose, respectively. These waiting periods were based on the maximum residue limit of 0.6 ppm as prescribed by the Codex Alimentarius Commission, Food Safety and Standards Authority of India, and European Commission. The study concludes that myclobutanil 10 WP is safe for consumers at both recommended and double recommended doses when applied 2 months before harvest. Risk assessment, considering the average daily apple consumption in India and theoretical maximum residue contributions (TMRCs), indicates negligible health hazards even at double the recommended dosage. The calculated TMRC values at Day 0 were significantly below the maximum permissible intake. For average and maximum myclobutanil residues at single and double doses, the TMRC values were found to be 0.0069 and 0.0070 mg day-1 person-1 and 0.0105 and 0.0106 mg day-1 person-1, respectively. These results indicate that myclobutanil, when used according to recommended dosages and waiting periods, poses minimal health risks to consumers. The study emphasizes the importance of prudent fungicide use to minimize fungicide residues on fruits, thereby ensuring their safety for consumption.

Determining Ultra-Low Organic Molecular Odor Thresholds in Air Helps Identify the Most Potent Fungal Aroma Compound

The determination of odor threshold values can be performed in various matrices, including air, and serves as a parameter to compare the potencies of odorous compounds. Typically, the odor thresholds in air are determined by gas chromatography-olfactory (GC-O) and referenced to an internal standard, most often (E)-dec-2-enal. Herein, a direct gas chromatography-flame ionization detector-olfactory analysis method for the determination of odor thresholds in air is reported. As model substrates for this novel approach, naturally occurring substances (R)-1-p-menthene-8-thiol as well as (3S,3aS,6R,7aS)-3,6-dimethyl-3a,4,5,6,7,7a-hexahydro-3H-1-benzofuran-2-one were used. The latter compound was synthesized from (-)-isopulegol and exhibited an extremely low odor recognition threshold of 1.9 × 10-6 ng L-1 air, the lowest value reported for a fungal aroma compound thus far.

Application of Chemical Ionization in the Analysis of Ethylphosphonic Acid Derivatives

The microsynthesis of 32 dialkyl derivatives of ethylphosphonic acid and the same number of monoalkyl derivatives was carried out to perform comparative studies using gas chromatography combined with mass spectrometry in chemical ionization mode which is one of the analytical techniques recommended by the Organisation for the Prohibition of Chemical Weapons (OPCW). The huge number of possible representatives makes it difficult to have complete spectral libraries of all substances in this class. Therefore, we decided to synthesize and instrumentally analyze only representatives of the selected series of homologues in this work. The analysis of the obtained results allowed us to find the rules for predicting mass spectra and the factors determining the retention parameters. Symmetrical diesters and monoesters of ethylphosphonic acid were selected for this study. During the conducted experiments using chemical ionization with methane as the reaction gas, protonated analyte molecules with high relative intensities were obtained; in many cases, these are base peaks in the spectrum. The obtained results allow grouping of the synthesized compounds depending on the introduced alkyl substituent. Retention data of the tested analytes were collected during the research by using electron ionization. The retention parameters of the tested compounds from each homologous series were also summarized and compared. Chemical Warfare Agents (CWA) analysis continues to be an important issue, especially in the context of the regular Proficiency Tests organized by the OPCW for identifying chemical compounds that are of interest to the Chemical Weapons Convention. Five compounds were synthesized whose spectra were not available in EI mass spectral libraries, and their retention indices were unknown. The identification of these substances was supported by the CI mass spectra and retention data, using previously developed relationships. Therefore, it is reasonable to conclude that the research method used is useful and effective.

Analyzing Alkyl Bromide Genotoxic Impurities in Febuxostat Based on Static Headspace Sampling and GC-ECD

Herein, a sensitive and selective gas chromatography-electron capture detector (GC-ECD) method was developed and validated for the quantification of trace levels of five bromo-containing genotoxic impurities in Febuxostat active pharmaceutical ingredient (API) after headspace sampling (HS). Multivariate experimental designs for the optimization of static headspace parameters were conducted in two stages using fractional factorial design (FFD) and central composite design (CCD). The optimum headspace conditions were 5 min of extraction time and a 120 °C extraction temperature. Baseline separation on the analytes against halogenated solvents was carried out using an Agilent DB-624 (30 m × 0.32 mm I.D., 1.8 μm film thickness) stationary phase under isothermal conditions. The method was validated according to ICH guidelines in terms of specificity, linearity, the limits of detection and quantification, precision and accuracy. The linearity was assessed in the range of 5-150% with respect to the specification limit. The achieved LOD and LOQ values ranged between 0.003 and 0.009 and 0.01 and 0.03 μg mL-1, respectively. The accuracy of the method (expressed as relative recovery) was in the range of 81.5-118.2%, while the precision (repeatability, inter-day) was less than 9.9% in all cases. The validated analytical protocol has been successfully applied to the determination of the impurities in various Febuxostat API batch samples.

Review of Developed Methods for Measuring Gas Uptake and Diffusivity in Polymers Enriched by Pure Gas under High Pressure

Gas emission and diffusion through polymeric materials play crucial roles in ensuring safety and monitoring gas concentrations in technology and industry. Especially, the gas permeation characteristics for O-ring material should be investigated for sealing application in a hydrogen infrastructure. To accommodate the requirements of different environments, we first developed four complementary effective methods for measuring the gas absorption uptake from polymers enriched by pure gas under high pressure and determining the gas diffusivity. The methods included the gravimetric method, the volumetric method, the manometric method, and gas chromatography, which are based on mass, volume, pressure, and volume measurements, respectively. The representative investigated results of the developed methods, such as gas uptake, solubility, and diffusivity are demonstrated. The measuring principles, measuring procedures, measured results, and the characteristics of the methods are compared. Finally, the developed methods can be utilized for testing transport properties, such as the leakage and sealing ability, of rubber and O-ring material under high pressure for hydrogen fueling stations and gas industry.

Covalent organic frameworks: spotlight on applications in the pharmaceutical arena

Covalent organic frameworks (COFs) have much potential in the field of analytical separation research due to their distinctive characteristics, including easy modification, low densities, large specific surface areas and permanent porosity. This article provides a historical overview of the synthesis and broad perspectives on the applications of COFs. The use of COF-based membranes in gas separation, water treatment (desalination, heavy metals and dye removal), membrane filtration, photoconduction, sensing and fuel cells is also covered. However, these COFs also demonstrate great promise as solid-phase extraction sorbents and solid-phase microextraction coatings. In addition to various separation applications, this work aims to highlight important advancements in the synthesis of COFs for chiral and isomeric compounds.

Molecular Docking and GC/MS-Based Approach for Identification of Anxiolytic Alkaloids from Griffinia (Amaryllidaceae) Species in a Zebrafish Model

Griffinia gardneriana Ravenna, Griffinia liboniana Morren and Griffinia nocturna Ravenna (Amarillydaceae) are bulbous plants found in tropical regions of Brazil. Our work aimed to determine the alkaloid profiles of Griffinia spp. and evaluate their anxiolytic potential through in vivo and in silico assays. The plants grown in greenhouses were dried and their ground bulbs were subjected to liquid-liquid partitions, resulting in alkaloid fractions that were analyzed by gas chromatography coupled to mass spectrometry (GC-MS). Anxiolytic activity was evaluated in zebrafish (Danio rerio) through intraperitoneal injection at doses of 40, 100 and 200 mg/kg in light-dark box test. GC-MS analyses revealed 23 alkaloids belonging to different skeleton types: lycorine, homolychorine, galanthamine, crinine, haemanthamine, montanine and narcisclasine. The chemical profiles were relatively similar, presenting 8 alkaloids common to the three species. The major component for G. gardneriana and G. liboniana was lycorine, while G. nocturna consisted mainly of anhydrolycorine. All three alkaloid fractions demonstrated anxiolytic effect. Furthermore, pre-treatment with diazepam and pizotifen drugs was able to reverse the anxiolytic action, indicating involving the GABAergic and serotonergic receptors. Molecular docking showed that the compounds vittatine, lycorine and 11,12-dehydro-2-methoxyassoanine had high affinity with both receptors, suggesting them to be responsible for the anxiolytic effect.

A Novel Method for the Determination of Squalene, Cholesterol and Their Oxidation Products in Food of Animal Origin by GC-TOF/MS

Cholesterol present in food of animal origin is a precursor of oxysterols (COPs), whose high intake through diet can be associated with health implications. Evaluation of the content of these contaminants in food is associated with many analytical problems. This work presents a GC-TOF/MS method for the simultaneous determination of squalene, cholesterol and seven COPs (7-ketocholesterol, 7α-hydroxycholesterol, 7β-hydroxycholesterol, 25-hydroxycholesterol, 5,6α-epoxycholesterol, 5,6β-epoxycholesterol, cholestanetriol). The sample preparation procedure includes such steps as saponification, extraction and silylation. The method is characterized by high sensitivity (limit of quantification, 0.02-0.25 ng mL-1 for instrument, 30-375 μg kg of sample), repeatability (RSD 2.3-6.2%) and a wide linearity range for each tested compound. The method has been tested on eight different animal-origin products. The COP to cholesterol content ratio in most products is about 1%, but the profile of cholesterol derivatives differs widely (α = 0.01). In all the samples, 7-ketocholesterol is the dominant oxysterol, accounting for 31-67% of the total COPs level. The levels of the other COPs range between 0% and 21%. In none of the examined products are cholestanetriol and 25-hydroxycholesterol present. The amount of squalene, which potentially may inhibit the formation of COPs in food, ranges from 2 to 57 mg kg-1.

Investigating the Effectiveness of Different Porous Nanoparticles as Drug Carriers for Retaining the Photostability of Pinosylvin Derivative

Pinosylvin monomethyl ether (PsMME) is a natural compound known for its valuable bioactive properties, including antioxidant and anti-inflammatory effects. However, PsMME's susceptibility to photodegradation upon exposure to ultraviolet (UV) radiation poses a significant limitation to its applications in the pharmaceutical field. This study, for the first time, introduces a strategy to enhance the photostability of PsMME by employing various nanoformulations. We utilized mesoporous silica nanoparticles (MSNs) coated with polydopamine via a poly(ethylene imine) layer (PDA-PEI-MSNs), thermally carbonized porous silicon nanoparticles (TCPSi), and pure mesoporous polydopamine nanoparticles (MPDA). All these nanocarriers exhibit unique characteristics, including the potential for shielding the drug from UV light, which makes them promising for enhancing the photostability of loaded drugs. Here, these three nanoparticles were synthesized and their morphological and physicochemical properties, including size and ζ-potential, were characterized. They were subsequently loaded with PsMME, and the release profiles and kinetics of all three nanoformulations were determined. To assess their photoprotection ability, we employed gas chromatography with a flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS) to assess the recovery percentage of loaded PsMME before and after UV exposure for each nanoformulation. Our findings reveal that MPDA exhibits the highest protection ability, with a remarkable 90% protection against UV light on average. This positions MPDA as an ideal carrier for PsMME, and by extension, potentially for other photolabile drugs as well. As a final confirmation of its suitability as a drug nanocarrier, we conducted cytotoxicity evaluations of PsMME-loaded MPDA, demonstrating dose-dependent drug toxicity for this formulation.

Compliance Testing of Hemp (Cannabis sativa L.) Cultivars for Total Delta-9 THC and Total CBD Using Gas Chromatography with Flame Ionization Detection

The United States Agriculture Improvement Act passed in December of 2018 legalized the growing of Cannabis sativa containing not more than 0.3% total Delta-9 tetrahydrocannabinol (THC) in the country. While Cannabis sativa has been cultivated for hundreds of years, the illegal status of the plant in the United States, and elsewhere, has hindered the development of plant cultivars that meet this legal definition. To assess sampling strategies, and conformance to the THC limit, 14 cultivars of hemp were grown and tested by using gas chromatography with flame ionization detection for total delta-9 THC and total cannabidiol (CBD) during 2020, 2021 and 2022. Each year, samples of fresh plant material were collected from each cultivar weekly, beginning in mid-August and ending in late October, to examine the rate of increase in THC and CBD for different cultivars and select individual plants. The sampling demonstrated that both CBD and THC increase rapidly over a 1-2-week time frame with maximum concentrations (about 16% and 0.6%, respectively) around late September to early October. The testing of individual plants on the same day for select cultivars showed that while the ratio of CBD to THC remains constant (about 20:1 in compliant hemp) during the growing season, the individual plants are highly variable in concentration. Whereas previous studies have shown cultivar-dependent variability in THC production, this study demonstrated a novel plant-to-plant variability in the levels of THC within the same hemp cultivar. Understanding variability within and between hemp cultivars is useful to determine field sampling strategies and to assess the risk of crop embargoes to growers by compliance regulators.

Impact of the Post-Harvest Period on the Chemical and Sensorial Properties of planifolia and pompona Vanillas

Vanilla production in Guadeloupe is expanding. The main species grown is Vanilla planifolia, but other species such as Vanilla pompona are also present and required by industries. To upgrade the value of vanilla production on this Caribbean Island, this study was performed to evaluate the aromatic specifies of these vanilla species according to the length of the post-harvest period (2 months and 9 months). For this purpose, Vanilla planifolia and Vanilla pompona were compared through scald and scarification transformation processes, as well as two different refining times (T1 and T2). For chemical characterization, 0.1 g of vanilla bean seeds was used for SMPE/GC-MS measurements, while 0.05 g of vanilla samples was subjected to infusion in milk (0.15%) for sensory evaluation. The latter involved generation of terms of aroma through olfaction and gustation sessions. The chemical results showed a significant difference between the two species, where vanillin was mostly present in Vanilla planifolia, unlike Vanilla pompona, where it was mainly rich in 4-methoxybenzyl alcohol. Interestingly, the second refining time was characterized by the appearance of two major components, 1,3-octadien and acetic acid. For sensory analysis, all the vanillas exhibited a high diversity of aromas including "sweet", "gourmand", "spicy" flavors and so on. The application of factorial correspondence analysis (FAC) as well as the agglomerative hierarchical clustering (AHC) showed differences between the vanilla samples according to both the species and refining time. The combination of these analyses makes it possible to establish a chemical and organoleptic profile of vanillas. Varietal and processing factors both have a major impact on the aroma profile of vanillas.

Antimicrobial Activity of Citrate-Coated Cerium Oxide Nanoparticles

The purpose of this study was to investigate the antimicrobial activity of citrate-stabilized sols of cerium oxide nanoparticles at different concentrations via different microbiological methods and to compare the effect with the peroxidase activity of nanoceria for the subsequent development of a regeneration-stimulating medical and/or veterinary wound-healing product providing new types of antimicrobial action. The object of this study was cerium oxide nanoparticles synthesized from aqueous solutions of cerium (III) nitrate hexahydrate and citric acid (the size of the nanoparticles was 3-5 nm, and their aggregates were 60-130 nm). Nanoceria oxide sols with a wide range of concentrations (10-1-10-6 M) as well as powder (the dry substance) were used. Both bacterial and fungal strains (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Proteus vulgaris, Candida albicans, Aspergillus brasielensis) were used for the microbiological studies. The antimicrobial activity of nanoceria was investigated across a wide range of concentrations using three methods sequentially; the antimicrobial activity was studied by examining diffusion into agar, the serial dilution method was used to detect the minimum inhibitory and bactericidal concentrations, and, finally, gas chromatography with mass-selective detection was performed to study the inhibition of E. coli's growth. To study the redox activity of different concentrations of nanocerium, we studied the intensity of chemiluminescence in the oxidation reaction of luminol in the presence of hydrogen peroxide. As a result of this study's use of the agar diffusion and serial dilution methods followed by sowing, no significant evidence of antimicrobial activity was found. At the same time, in the current study of antimicrobial activity against E. coli strains using gas chromatography with mass spectrometry, the ability of nanoceria to significantly inhibit the growth and reproduction of microorganisms after 24 h and, in particular, after 48 h of incubation at a wide range of concentrations, 10-2-10-5 M (48-95% reduction in the number of microbes with a significant dose-dependent effect) was determined as the optimum concentration. A reliable redox activity of nanoceria coated with citrate was established, increasing in proportion to the concentration, confirming the oxidative mechanism of the action of nanoceria. Thus, nanoceria have a dose-dependent bacteriostatic effect, which is most pronounced at concentrations of 10-2-10-3 M. Unlike the effects of classical antiseptics, the effect was manifested from 2 days and increased during the observation. To study the antimicrobial activity of nanomaterials, it is advisable not to use classical qualitative and semi-quantitative methods; rather, the employment of more accurate quantitative methods is advised, in particular, gas chromatography-mass spectrometry, during several days of incubation.

Characteristic Evaluation of Gas Chromatography with Different Detectors for Accurate Determination of Sulfur Hexafluoride

Sulfur hexafluoride (SF6), which survives in the atmosphere for an extremely long period of time, is the most potent greenhouse gas regulated under the Kyoto Protocol. So, the accurate monitoring of atmospheric SF6 plays an important role in the study of the control policies for reducing greenhouse gas emissions. The instruments for SF6 measurement are typically calibrated using certified reference materials. The concentrations of the commercially available SF6 reference materials usually have a broad range, from 1 μmol/mol to 6000 μmol/mol. Some characteristics including sensitivity, linear range, relative standard deviation, and accuracy are crucial for the determination of SF6 in such a broad concentration range. Therefore, the selection of a proper detector for the accurate determination of SF6 with such a broad range is extremely important to establish a gas chromatography (GC) method for developing SF6 reference materials. In this paper, several typical GC methods with different detectors, including a thermal conductivity detector (TCD), a pulsed discharge helium ionization detector (PDHID), and a flame photometric detector (FPD), were carefully established for the accurate determination of SF6 with different concentrations. The results show that an FPD detector has a relatively narrow linearity range, thus a quadratic equation should be established for building a calibration curve. The PDHID and TCD have good linearity with coefficients of 1.0000 in the concentration range of 10-100 μmol/mol (using a PDHID), and 100-1000 μmol/mol (using a TCD), respectively. Further considering the measurement errors of indication results, the PDHID is suitable for SF6 measurement when the concentrations are below 100 μmol/mol, whereas the TCD is suitable for SF6 measurement when the concentrations are over 100 μmol/mol. These results provide useful guidance in choosing an appropriate GC detector for the accurate determination of SF6, which are especially very helpful for developing SF6 reference materials.

Detection of Adulterated Oregano Samples Using Untargeted Headspace-Gas Chromatography-Ion Mobility Spectrometry Analysis

Oregano is often adulterated for economic reasons. This fraud mainly consists of adding other species with lower commercial value, such as olive leaves. To ensure the authenticity of oregano, an analytical method based on the analysis of the volatile organic compound (VOC) profile obtained by headspace gas chromatography coupled to ion mobility spectrometry (HS-GC-IMS) was developed and validated. Samples of ecological Mediterranean oregano adulterated with different percentages of two types of olive leaves (cornicabra and manzanilla) were studied using a non-targeted analysis. Moreover, a total of 30 VOCs were identified in the analyzed samples, and 24 compounds could be quantified using calibration curves based on Boltzmann's equation. A chemometric model based on orthogonal partial least squares discriminant analysis (OPLS-DA) was used to detect the adulterated oregano samples, obtaining a 100% validation success rate, and partial least squares (PLS) analysis was used to quantify the percentage of adulterant. Finally, the proposed methodology was applied to 15 commercial oregano samples, resulting in two of them being classified as adulterated with 31 and 43% of olive leaves, respectively.

Exploring aromatic components differences and composition regularity of 5 kinds of these 4 aroma types Phoenix Dancong tea based on GC-MS

Different aromatic components do indeed give different tea flavors. There is still little research on whether there is a certain regularity in the combination and content of aromatic components in different aroma types of Phoenix Dancong (PDC) tea. This potential regularity may be a key factor in unraveling the relationship between reproduction and evolution in PDC tea. Here, the 5 kinds of these 4 aroma types PDC tea (Zhuye, Tuofu, Jianghuaxiang, Juduo, Yashixiang) were used as research materials in this study, the headspace solid-phase microextraction combined with gas chromatography-mass spectrometry was used to analyze the aromatic components of these PDC teas. The results showed a total of 36 aromatic components identified in this study. When conducting cluster analysis, it was found that similarity degree arrangement sequence of 5 PDC teas was Juduo, Tuofu, Yashixiang, Zhuye and Jianghuaxiang. Among these aromatic components, the 7,9-Di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione, the 2-Cyclopenten-1-one, 3-methyl-2-(2-pentenyl)-,(Z)-, the 2,4-Di-tert-butylphenol, the 3,7-dimethyl-1,5,7-Octatrien-3-ol, and the 2-Furanmethanol,5-ethenyltetrahydro-.alpha.,.alpha.,5-trimethyl-,cis- are common to 5 PDC teas. This study aims to elucidate the similarities in the aromatic components of 5 PDC teas, revealing the major aroma-endowed substances of various aroma, and providing theoretical reference for further exploring the relationship between aroma type discrimination, variety selection, and evolution of PDC teas.

Suspect Screening Analysis of Pooled Human Serum Samples Using GC × GC/TOF-MS

Humans interact with thousands of chemicals. This study aims to identify substances of emerging concern and in need of human health risk evaluations. Sixteen pooled human serum samples were constructed from 25 individual samples each from the National Institute of Environmental Health Sciences' Clinical Research Unit. Samples were analyzed using gas chromatography (GC) × GC/time-of-flight (TOF)-mass spectrometry (MS) in a suspect screening analysis, with follow-up confirmation analysis of 19 substances. A standard reference material blood sample was also analyzed through the confirmation process for comparison. The pools were stratified by sex (female and male) and by age (≤45 and >45). Publicly available information on potential exposure sources was aggregated to annotate presence in serum as either endogenous, food/nutrient, drug, commerce, or contaminant. Of the 544 unique substances tentatively identified by spectral matching, 472 were identified in females, while only 271 were identified in males. Surprisingly, 273 of the identified substances were found only in females. It is known that behavior and near-field environments can drive exposures, and this work demonstrates the existence of exposure sources uniquely relevant to females.

Discovery of potential biomarkers for osteoporosis using LC/GC-MS metabolomic methods

Purpose

For early diagnosis of osteoporosis (OP), plasma metabolomics of OP was studied by untargeted LC/GC-MS in a Chinese elderly population to find possible diagnostic biomarkers.

Methods

A total of 379 Chinese community-dwelling older adults aged ≥65 years were recruited for this study. The BMD of the calcaneus was measured using quantitative ultrasound (QUS), and a T value ≤-2.5 was defined as OP. Twenty-nine men and 47 women with OP were screened, and 29 men and 36 women were matched according to age and BMI as normal controls using propensity matching. Plasma from these participants was first analyzed by untargeted LC/GC-MS, followed by FC and P values to screen for differential metabolites and heatmaps and box plots to differentiate metabolites between groups. Finally, metabolic pathway enrichment analysis of differential metabolites was performed based on KEGG, and pathways with P ≤ 0.05 were selected as enrichment pathways.

Results

We screened metabolites with FC>1.2 or FC<1/1.2 and P<0.05 and found 33 differential metabolites in elderly men and 30 differential metabolites in elderly women that could be potential biomarkers for OP. 2-Aminomuconic acid semialdehyde (AUC=0.72, 95% CI 0.582-0.857, P=0.004) is highly likely to be a biomarker for screening OP in older men. Tetradecanedioic acid (AUC=0.70, 95% CI 0.575-0.818, P=0.004) is highly likely to be a biomarker for screening OP in older women.

Conclusion

These findings can be applied to clinical work through further validation studies. This study also shows that metabolomic analysis has great potential for application in the early diagnosis and recurrence monitoring of OP in elderly individuals.

Characterization of Larix decidua Mill. (Pinaceae) oleoresin's essential oils composition using GC-MS

Introduction

Larch oleoresin has been described regarding several biological activities and medicinal applications, such as wound healing and treatment of ulcers, but little is known about its chemical composition.

Material and methods

Eight oleoresins from Larix decidua Mill. obtained from four companies and one adulterated control were therefore investigated to determine their content of essential oils and to verify possible differences in their composition in relation to the harvest and manufacturing processes. Essential oils (EOs) were isolated by distillation and the yield was analysed.

Results and discussion

The yield of EO varied among all samples. The yield of the pure larch samples covered a range of 7.8% to 15.5%. A higher yield (19.0%) was observed for adulterated control, which contained oleoresins from different Pinaceae trees. Age of samples had no impact on yield. However, there was a significant statistical variation (p<0.05) in the yields of the mid-summer oleoresins (>10%) compared to early or late summer (<10%), emphasising the importance of the time of collection. Samples were subsequently analysed by GC-MS. EO samples confirmed the presence of various chemical classes, such as monoterpenes, sesquiterpenes, and diterpenes. α-pinene was the compound with the highest concentrations (>50%), followed by β-pinene (>6%), D-limonene (>2.5%), α-terpineol (>0.9%), β-myrcene (>0.2%), and 3-carene (>0.05%). Samples were grouped using multivariate data analysis (MVDA) with respect to the chemical variation between the oleoresins' EOs. The resulting four clusters were named low (low yield obtained for the samples), mixed (mixed oleoresin from different Pinaceae species, adulteration control), old (old oleoresin kept in the institute), and normal (other oleoresins) samples, each presenting distinct chemical biomarkers. There were considerable differences between site and time of collection. Essential oil yield did not always meet requirements as defined by the German Homeopathic Pharmacopoeia. In addition, adulterated or aged samples could be identified as compared to pure and fresh larch oleoresins.

Conclusion

We conclude that larch oleoresin used for pharmaceutical applications has to be carefully analysed and standardised to guarantee reproducible product quality.

[Research progress of stationary phase of gas chromatography based on chiral organic frameworks]

Enantiomers typically show different pharmacological, toxicological, and physiological properties. Thus, the preparation of enantiopure compounds is of great significance for human health and sustainable development. Compared with asymmetric catalysis, enantiomeric separation is simpler, faster, and more efficient; as such, it has become the preferred method for obtaining pure enantiomers. At present, enantiomeric separation methods mainly include chromatography, nanochannel membrane separation, selective adsorption, and recrystallization. In particular, gas chromatography (GC) plays an important role in enantioseparation because of its high sensitivity, excellent reproducibility, and outstanding processing capacity for various enantiomers. The stationary phase is key to the separation efficiency of GC, and more efficient, stable, and cost-effective materials that could serve as stationary phases are constantly being explored. Organic frameworks, such as covalent organic frameworks (COFs), metal-organic frameworks (MOFs), porous organic cages (POCs), metal-organic cages (MOCs), and hydrogen-bonded organic frameworks (HOFs), possess large specific surface areas, high porosities, tunable pore sizes, and easy functionalization, rendering them promising candidates for the separation of mixed analytes. Research has shown that the use of organic frameworks as stationary phases for GC results in excellent column efficiency and high resolution for various analytes, including n-alkanes, n-alcohols, polycyclic aromatic hydrocarbons, positional isomers, and organic fluorides. Furthermore, organic frameworks can be prepared as chiral stationary phases for GC by the intelligent introduction of a chiral moiety, thereby enabling the efficient separation of enantiomers. Synthetic strategies for chiral organic frameworks are primarily categorized as post-synthesis or bottom-up approaches. In general, the post-synthesis strategy can introduce various chiral sites to the framework; however, the distribution of chiral sites may not be uniform, and the ordered framework may be destroyed during the post-synthesis process. The bottom-up strategy allows for the uniform and precise distribution of chiral sites in the framework, but the synthesis of chiral monomers and the constraint between asymmetry and crystallinity limit its development. Chiral induction has been proposed as an alternative strategy for synthesizing chiral organic frameworks. The use of this strategy has led to the successful preparation of organic frameworks with abundant chiral sites and excellent crystallinity. Dynamic coating and in situ growth are the main approaches used to transform the as-prepared chiral organic frameworks into stationary phases. Notably, the in situ growth approach can yield chiral COF/MOF-coated capillary columns that provide high resolution for the separation of enantiomers with excellent repeatability and reproducibility. Nevertheless, owing to the slightly complex pretreatment process and the difficulty of synthesizing chiral organic frameworks, the in situ growth approach has not yet been widely applied. Owing to their excellent solvent processing performance, POCs, MOCs, and HOFs can be easily coated on the inner walls of columns to form membranes via dynamic or static coating. A series of enantiomers have been successfully separated and analyzed by immobilizing chiral COFs, MOFs, POCs, MOCs, and HOFs on GC capillary columns, demonstrating the great potential of chiral organic frameworks for enantiomeric separation. In general, the mechanisms by which chiral organic frameworks recognize enantiomers could be mainly categorized as van der Waals interactions, hydrogen bonding, π-π interactions, and size-exclusion effects. While molecular simulations can offer some insights into these recognition mechanisms, clarifying these mechanisms based on effective characterization remains challenging. In summary, organic frameworks show outstanding advantages for enantiomer separation. Given breakthroughs in synthetic strategies for chiral organic frameworks and the in-depth study of chiral recognition mechanisms, chiral organic frameworks may be expected to become an important aspect in the field of chiral materials, further realizing the large-scale analysis and production of chiral analytes. A total of 64 references, most of which are from the American Chemical Society, Springer Nature, Wiley Online Library, and Elsevier databases, are cited in this review.

Formation of Epoxy Fatty Acids in Triacylglycerol Standards during Heating

Epoxy fatty acid formation during heating was estimated using triolein (OOO) and trilinolein (LLL). Epoxy octadecanoic acids were found in heated OOO, while epoxy octadecenoic acids were found in heated LLL. The content of epoxy fatty acids increased with heating time, and trans-epoxy fatty acids were formed significantly more than cis-epoxy fatty acids. A comparison between OOO and LLL indicated that epoxy fatty acid formation was higher in the OOO than that in the LLL. Heating tests in the presence of α- tocopherol suggested that the formation of epoxy fatty acids could be suppressed by antioxidants.

Recent advances in mass spectrometry for the detection of doping

INTRODUCTION

The analysis of doping control samples is preferably performed by mass spectrometry, because obtained results meet the highest analytical standards and ensure an impressive degree of reliability. The advancement in mass spectrometry and all its associated technologies thus allow for continuous improvements in doping control analysis.

AREAS COVERED

Modern mass spectrometric systems have reached a status of increased sensitivity, robustness, and specificity within the last decade. The improved sensitivity in particular has, on the other hand, also led to the detection of drug residues that were attributable to scenarios where the prohibited substances were not administered consciously but rather by the unconscious ingestion of or exposure to contaminated products. These scenarios and their doubtless clarification represent a great challenge. Here, too, modern MS systems and their applications can provide good insights in the interpretation of dose-related metabolism of prohibited substances. In addition to the development of new instruments itself, software-assisted analysis of the sometimes highly complex data is playing an increasingly important role and facilitating the work of doping control laboratories.

EXPERT OPINION

The sensitive analysis and evaluation of a higher number of samples in a shorter time is made possible by the ongoing developments in mass spectrometry.

Exploring columns based on cyclodextrin derivatives dissolved into polysiloxanes

The main goal of this work is to expand the availability of chiral columns for the analysis of agrochemicals by gas chromatography. A broader offer of chiral stationary phases would allow shifting toward enantioselective analytical techniques environmentally more friendly for those compounds. We prepared seven chiral capillary columns based on derivatives of either, β-cyclodextrin or γ-cyclodextrins dissolved at high concentrations, in two typical polysiloxanes with different polarities, demonstrating not only the significance of the chiral selector but also of the polymer solvent for achieving adequate enantioseparation of some agrochemicals. The enantiorecognition ability of each column was evaluated with 20 volatile and semivolatile agrochemicals, possessing one or two chiral centers. Besides, to elute more polar agrochemicals, as well as to enhance enantioselectivity, three derivatization procedures targeting the carboxyl and/or amine group were evaluated. The results revealed that the prepared column consisting of octakis(2,3-di-O-acetyl-6-O-tertbutyldimethylsilyl)-γ-cyclodextrin dissolved in (14%-cyanopropyl-phenyl)-86%-methyl-polysiloxane provides the broadest enantiorecognition capacity. This column allowed the enantioseparation of seventeen chiral agrochemicals, including metalaxyl, furalaxyl, and four imidazolinones, which were not enantioseparated in the remaining columns. To the best of our knowledge, glufosinate, fluorochloridone, fenarimol, furalaxyl, and four imidazolinones were enantioseparated by gas chromatography for the first time.

Stability study and development of the validated infrared spectrometric method for quantitative analysis of sevoflurane compared with the gas chromatographic method

Sevoflurane, also called fluoromethyl ether, is an inhalation anesthetic agent used to initiate and maintain general anesthesia for adults and pediatric patients during surgical procedures. Several analytical methods have previously been applied to follow the properties and quality of sevoflurane, including mass spectrometry and gas chromatography methods. These methods are practically tedious and need sophisticated apparatus. In the present work, an attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometric method was used for the quantitative determination of sevoflurane which is characterized as a fast, accurate, and available technique for most pharmaceutical laboratories, besides the gas chromatographic method which is the most suitable for the detection of impurities. Sevoflurane is a liquid and it is applied directly on the glass top of the ATR-FTIR either as a concentrated solution or diluted with hexane as a diluent, which did not interfere with sample determination within the specified wavelength range of the IR spectrum, particularly the wavelength of the ethereal group at 1200 cm-1. This method can be applied to the identification test and quantitative assay of sevoflurane since it is validated for the precision, accuracy, reproducibility, and specificity in the analysis of sevoflurane as a pharmaceutical product. However, still, there is a need for a gas chromatographic method to detect the impurities and degradation products during the stability study of sevoflurane.

Composition and Anti-Acetylcholinesterase Properties of the Essential Oil of the Ecuadorian Endemic Species Eugenia valvata McVaugh

Alzheimer's disease is a global health problem due to the scarcity of acetylcholinesterase inhibitors, the basis for symptomatic treatment of this disease; this requires new approaches to drug discovery. In this study, we investigated the chemical composition and anticholinesterase activity of Eugenia valvata McVaugt (Myrtaceae) collected in southern Ecuador, which was obtained as an essential oil (EO) with a yield of 0.124 ± 0.03% (w/w); as a result of the chemical composition analysis, a total of 58 organic compounds were identified-representing 95.91% of the total volatile compounds-using a stationary phase based on 5% phenyl-methylpolysiloxane, as analyzed via gas chromatography coupled to mass spectrometry (GC-MS) and flame ionization detection (GC-FID). The main groups were hydrocarbon sesquiterpenes (37.43%), oxygenated sesquiterpenes (31.08%), hydrocarbon monoterpenes (24.14%), oxygenated monoterpenes (0.20%), and other compounds (3.058%). Samples were characterized by the following compounds: α-pinene (22.70%), α-humulene (17.20%), (E)-caryophyllene (6.02%), citronellyl pentanoate (5.76%), 7-epi-α-eudesmol (4.34%) and 5-iso-cedranol (3.64%); this research was complemented with an enantioselective analysis carried out using 2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin as a stationary phase chiral selector. As a result, α-pinene, limonene, and α-cadinene enantiomers were identified; finally, in the search for new active principles, the EO reported strong anticholinesterase activity with an IC50 of 53.08 ± 1.13 µg/mL, making it a promising candidate for future studies of Alzheimer's disease.

Identification of Terpene Compositions in the Leaves and Inflorescences of Hybrid Cannabis Species Using Headspace-Gas Chromatography/Mass Spectrometry

Although cannabidiol and tetrahydrocannabinol in Cannabis species exert their pharmacological effects via the endocannabinoid system, it is believed that other phytochemicals, particularly terpenes, can modulate therapeutic outcomes through the entourage effect. Therefore, to gain a better understanding of the pharmacological effects of Cannabis, obtaining information on phytochemical compositions, including mono-, di-, and sesqui-terpenes in Cannabis species is essential. Applying a sophisticated analytical method is indispensable. In this study, headspace-gas chromatography/mass spectrometry (HS-GC/MS) was employed to identify major terpenes in the leaves and inflorescences of hybrid Cannabis species. The incubation time and temperature conditions for HS-GC/MS were optimized. This method was successfully applied to the leaves (n = 9) and inflorescences (n = 7) of hybrid Cannabis species. A total of 26 terpenes in Cannabis species were detected, and six major components, such as α-pinene (9.8-2270 μg/g), β-pinene (2.6-930 μg/g), myrcene (0.7-17,400 μg/g), limonene (1.3-300 μg/g), β-caryophyllene (60-3300 μg/g), and α-humulene (40-870 μg/g), were quantified. Each sample showed different terpene compositions, but six major terpenes among all the terpenes detected were consistently found in both the leaves and inflorescences of hybrid Cannabis species. In this study, the six major terpenes' potential in hybrid Cannabis species was evaluated as biomarkers to distinguish hybrid Cannabis species samples. This study contributes to a better understanding of the entourage effect of Cannabis-based botanical drugs.

Residues of Deltamethrin in Pine Needles and Pine Nuts of Catalonia (Spain)

In recent years, recurrent droughts have weakened stone pine (Pinus pinea) forests and facilitated the emergence of harmful pests and diseases, including the Leptoglossus occidentalis. The production of stone pine nuts has declined over the past five years. To control this hemipteran pest, a synthetic pyrethroid insecticide called deltamethrin is being tested. However, it is necessary to estimate the residue left by these treatments in forest stands. Therefore, a fast and robust analytical procedure was developed based on QuEChERS clean-up extraction, followed by gas chromatography coupled with an electron capture detector. This optimized method can detect residual concentrations of deltamethrin in pine nuts and pine needles up to 0.1 and 6 μg kg-1, respectively, with a limit of quantification of 0.4 and 20 μg kg-1. Great recoveries (between 84 and 102%) were obtained for both matrices, and no matrix effect was observed. The results showed that two weeks after spraying, the deltamethrin content in the needles of stone pines decreased by up to 75%, and after nine months, its presence was like that of nontreated trees.

A Compact Monitor for Ethylene and Other Plant-Produced Volatile Organic Compounds for NASA Space Missions

In this work, we discuss the development of a compact analytical instrument for monitoring ethylene in compact greenhouses utilized by NASA to grow fresh vegetables in space. Traditionally, ethylene measurements are conducted by GC-MS systems. However, in space, they are not applicable due to their bulky size, heavy weight, special carrier gas requirement and high maintenance. Our group developed a compact and robust battery-powered ethylene monitor based on the principles of analytical gas chromatography. The device utilizes purified ambient air as a carrier gas and a metal oxide sensor as a GC detector. Implementation of a CarboWax 20 M packed column from Restek together with a Tenax TA pre-concentrator allowed us to achieve a 20 ppb limit of detection for ethylene. Full automation of measurements and reporting of concentrations was accomplished via the implementation of a Raspberry Pi 4 computer and a 7″ 720P LED capacitive touchscreen utilized for data output. Based on a feasibility study, a fully automated, industrial-grade ethylene monitoring and removal system for greenhouses was developed.

Association between Serum Free Fatty Acids and Clinical and Laboratory Parameters in Acute Heart Failure Patients

Very little is known about the association between individual serum free fatty acids (FFAs) and clinical and laboratory parameters (indicators of heart failure severity) in acute heart failure (AHF) patients. Here, the baseline serum levels of FFAs, 16:0 (palmitic acid), 16:1 (palmitoleic acid), 18:0 (stearic acid), 18:1 (oleic acid), 18:2 (linoleic acid), 18:3 (alpha-linolenic acid or gamma-linolenic acid), 20:4 (arachidonic acid), 20:5 (eicosapentaenoic acid), and 22:6 (docosahexaenoic acid), were determined in 304 AHF patients (94.7% belonged to New York Heart Association functional class IV) using gas chromatography. Spearman correlation coefficients were used to examine the associations between the individual and total (the sum of all FFAs) FFAs and clinical and laboratory parameters. After applying a Bonferroni correction to correct for multiple testing, the total FFAs, as well as the individual FFAs (except FFAs 18:0, 20:5, and 22:6), were found to be significantly positively correlated with serum albumin. Only a few additional associations were found: FFA 16:0 was significantly negatively correlated with systolic pulmonary artery pressure, FFA 18:3 was significantly negatively correlated with C-reactive protein and body mass index, and FFA 20:4 was significantly negatively correlated with blood urea nitrogen. Based on our results, we conclude that in patients with severe AHF, individual and total serum FFAs are slightly associated with established laboratory and clinical parameters, which are indicators of heart failure severity.

Investigation of potential migratables from paper and board food contact materials

Since the ban on single-use plastic articles in Europe, the food contact material (FCM) industry has been forced to move to more sustainable alternatives. Paper and board FCM are convenient alternatives but must be safe for consumers. This study aims to investigate potential migrations of various substances (e.g., plasticizers, photoinitiators, primary aromatic amines, mineral oil, and bisphenols) from straws and takeaway articles made of paper and board. Twenty straws and fifty-eight takeaway articles were carefully selected and investigated using liquid and gas chromatography coupled with tandem mass spectrometry or flame ionization detector. Fourteen substances of all the targeted categories were found in takeaway articles, including seven plasticizers, two photoinitiators, one primary aromatic amine, two bisphenols, and the saturated and aromatic fraction of mineral oil (MOSH and MOAH, respectively). In straws, fewer substances were detected, i.e., six substances, including three plasticizers, one photoinitiator, MOSH, and MOAH. At least one of the target substances was detected in 88% of the samples, demonstrating the importance of further evaluation of these materials. Finally, the associated risks were assessed, highlighting the potential risks for several types of articles regarding bisphenol A, one primary aromatic amine (3.3-DMB), and MOSH and MOAH.

General Two-Step Method for the Fabrication of Covalent-Organic Framework-Bound Open-Tubular Capillary Columns for High-Resolution Gas Chromatography Separation of Isomers

Covalent organic frameworks (COFs) are promising as stationary phases for gas chromatography (GC). The successful anchoring of COFs to the inner walls of the capillary with good uniformity is an important prerequisite to ensure the excellent separation performance of columns. However, current methods for the fabrication of COF-based capillary columns cannot always meet this requirement when faced with different COFs, which hampers the further development of COF-based GC stationary phases. Here, we show a general two-step method for the fabrication of COF-bound capillary column. The first step enables the formation of uniform amorphous polymer layer on the inner walls of capillary, while the second step allows the facile transformation of the amorphous polymer layer into a highly crystalline COF layer. COF-bound capillary columns with different framework structures were fabricated successfully by the developed two-step method. Impressively, the COF layers bound on the inner walls of these capillary columns showed good uniformity and high crystallinity. More importantly, as an example, the fabricated Tab-DHTA-bound capillary column showed good resolution (R > 1.5) and high column efficiency (700-39,663 plates m-1) for the tested isomers of ethylbenzene, xylene, dichlorobenzene, chlorotoluene, pinene, 1,3-dichloropropene, and propylbenzene with good precision (RSD, run-to-run, n = 5) (retention time, 0.2-0.6%; peak area, 0.5-1.1%; and peak height, 0.5-1.4%). In general, the fabricated Tab-DHTA-bound capillary column exhibited better performance for the separation isomers than commercial columns DB-5 and HP-FFAP. These results indicate that the two-step method is an efficient way to fabricate the COF-bound capillary column with excellent separation performance.

Pink pepper (Schinus terebinthifolius Raddi) essential oil: phytochemical composition and cytotoxic activity

Pink pepper (Schinus terebinthifolius Raddi) is a native species native from Central and South America that produces an essential oil (EOpp) with promising applications. This work aimed to investigate the chemical composition and cytotoxic activity of EOpp extracted from unripe (U-EOpp) and ripe (R-EOpp) pink pepper fruits. U-EOpp and R-EOpp were extracted using the hydrodistillation technique and analysed using NMR and GC-MS. U-EOpp and R-EOpp cytotoxic activity was assessed using HL-60 (acute promyelocytic leukemia) and SK-MEL-28 (malignant melanoma) cell lines by MTT assay. Results showed that α-pinene (29.16%), dl-Limonene (20.65%), and ρ-cymene (15.86%) were U-EOpp major components. In addition, l-phellandrene (38.91%), Sylvestrene (23.02%), and α-pinene (21.62%) were R-EOpp major components. U-EOpp showed cytotoxic activity at 37.5 and 18.7 µg/mL for SK-MEL-28 and HL-60, respectively. R-EOpp showed cytotoxic activity for HL-60 at 100 µg/mL. Therefore, EOpp may represent a remarkable source of active natural compounds used in traditional Brazilian medicine.

OMNI: Gas Chromatograph Captures Seven Common PET Radiotracer Analytes in under 5 Minutes

A novel gas chromatography method was developed using automatic injections to identify and quantify the amount of residual solvents or analytes in samples of fluorine-18 and carbon-11 radiopharmaceuticals. This approach evaluates seven analytes in less than 5 versus 13 min of acquisition time. The method additionally includes a 3 min bakeout to aid in the removal and carry-over of higher-boiling impurities. Chromatographic parameters such as column temperature, hold time, column pressure, flow rate, and split ratios were adjusted and optimized to analyze radioactive drug samples containing analytes which include methanol, ethanol, acetone, acetonitrile, triethylamine, N,N-dimethylformamide, and dimethyl sulfoxide. The relative standard deviation for each solvent was determined to be no greater than 1.6%. The method limit of detection (LOD) and limit of quantification (LOQ) were between 0.053 and 0.163 and 0.000 (5.791 × 10-6) and 0.520 mg/mL, respectively. This GC technique, using flame ionization detection (FID), was validated and is currently employed for the routine quality control of all approved IND and RDRC PET radiopharmaceuticals at our center.

Effects of Harvest Time and Hydrodistillation Time on Yield, Composition, and Antioxidant Activity of Mint Essential Oil

In this study, we assessed the effects of different harvest times (9 a.m., 1 p.m., and 5 p.m.) and hydrodistillation times (60, 90, and 120 min) on the yield, chemical composition, and antioxidant activity of the spearmint (Mentha spicata L.) essential oil (EO) sourced from the Amazon region. EO yield was ≥1.55% and was not significantly influenced (p ≥ 0.05) by the different harvest times and hydrodistillation times. Thirty-one different organic compounds were identified, of which menthol (91.56-95.68%), menthone (0.6-2.72%), and isomenthone (0.55-1.46%) were the major constituents. The highest menthol content in the EO was obtained from samples collected at 9 a.m., with a hydrodistillation time of 60-90 min, compared to other harvest and hydrodistillation times. This suggests that exposure to sun and light, which is greater at harvest times of 1 p.m. and 5 p.m., decreased the menthol content and altered the chemical composition of Mentha EO. Furthermore, the sample harvested at 9 a.m. and hydrodistilled for 60 min showed the highest antioxidant activity (61.67 equivalent mg of Trolox per g of EO), indicating that antioxidant activity is strongly affected by light exposure and the contact duration of the sample with boiling water during hydrodistillation.

Growth and fatty acid composition of pikeperch (Sander lucioperca L., 1758) larvae under altered feeding protocol including the copepod Apocyclops panamensis (Marsh, 1913)

Alternative live feeds for small and sensitive fish early life stages such as pikeperch (Sander lucioperca L., 1758) can improve the larval quantity, quality and performance in aquaculture. Therefore, this study evaluated the cyclopoid copepod Apocyclops panamensis (Marsh, 1913) as live feed for pikeperch larviculture from day 11 post hatch (dph) in two independent experiments. In both experiments, pikeperch larvae had the highest specific growth rate (SGR) when they fed on Brachionus plicatilis until dph 11 and A. panamensis until dph 16-18. SGR was related to a decrease in total fatty acids (FAs), saturated FAs and monounsaturated FAs in pikeperch larvae, indicating their use as energy for growth. Within the polyunsaturated FAs, docosahexaenoic acid (DHA) increased in larvae fed with A. panamensis and coincided with the highest SGR suggesting that DHA is accumulated in larvae as structural FA. Our study demonstrated a suitable pikeperch larval fatty acid composition for growth after feeding A. panamensis compared with Artemia sp. from dph 11 until dph 16 and previously fed with B. plicatilis. Moreover, it highlighted the importance of the dietary PUFAs in pikeperch rearing, specifically of linoleic acid (LA) from dph 4 until dph 11 and of DHA from dph 11 onwards.

Pterodon emarginatus Seed Preparations: Antiradical Activity, Chemical Characterization, and In Silico ADMET Parameters of β-caryophyllene and Farnesol

The study of medicinal plants and their active compounds is relevant to maintaining knowledge of traditional medicine and to the development of new drugs of natural origin with lower environmental impact. From the seeds of the Brazilian plant Pterodon emarginatus, six different preparations were obtained: essential oil (EO), ethanol extract (EthE) prepared using the traditional method, and four extracts using solvents at different polarities, such as n-hexane, chloroform, ethyl acetate, and methanol (HexE, ChlE, EtAE, and MetE). Chemical characterization was carried out with gas chromatography, allowing the identification of several terpenoids as characteristic components. The two sesquiterpenes β-caryophyllene and farnesol were identified in all preparations of Pterodon emarginatus, and their amounts were also evaluated. Furthermore, the total flavonoid and phenolic contents of the extracts were assessed. Successively, the antiradical activity with DPPH and ORAC assays and the influence on cell proliferation by the MTT test on the human colorectal adenocarcinoma (HT-29) cell line of the preparations and the two compounds were evaluated. Lastly, an in silico study of adsorption, distribution, metabolism, excretion, and toxicity (ADMET) showed that β-caryophyllene and farnesol could be suitable candidates for development as drugs. The set of data obtained highlights the potential medicinal use of Pterodon emarginatus seeds and supports further studies of both plant preparations and isolated compounds, β-caryophyllene and farnesol, for their potential use in disease with free radical involvement as age-related chronic disorders.

Changes in methamphetamine impurity profiles induced by tert-butoxycarbonylation

Analysis of impurities in methamphetamine (MA) can be used to characterize MA seizures, investigate the relationship among MA seizures, and provide information on their synthetic routes. Recently, chemically derivatized MA, such as tert-butoxycarbonyl (t-Boc) MA, has been seized and attracted attention because routine forensic analysis methods may fail to correctly identify them. Chemical derivatization is a simple method for protection and deprotection of a compound, and protection of MA using t-Boc can be used to mask the MA. Although t-Boc derivatization might alter the impurity profile of MA, the actual changes in the impurity profile have not been investigated. In this study, changes in the MA impurity profile with tert-butoxycarbonylation were explored. MA and some typical impurities were derivatized using di-tert-butyl dicarbonate and water. Analysis of the impurities in five MA samples by gas chromatography showed that peaks both appeared and disappeared for the deprotected MA compared with the original MA. However, typical impurities important for characterizing MA seizures were conserved after derivatization and deprotection. Most of the new peaks were speculated to be contaminants introduced during derivatization and deprotection. A peak giving a mass spectrum similar to that of t-Boc MA was detected in the chromatograms of t-Boc MA and deprotected MA. Although the origin of this peak was not determined, it might be a marker for the MA involving tert-butoxycarbonylation. These results indicate that tert-butoxycarbonylation can alter the MA impurity profile; therefore, care is needed when interpreting results for derivatized MA.

[Comparison of fat determination methods and analysis of fatty acids in tea]

OBJECTIVE

Comparative analysis of two method for determining fat and analysis of fatty acid content in tea samples.

METHODS

The content of freefatand total fat in tea was determined by Soxhlet extraction method and acid hydrolysis method, and the content of fatty acids were determined by gas chromatography. The composition and content of fatty acids in 21 tea samples from 5 regions were analyzed.

RESULTS

The freefat content of tea determined by Soxhlet extraction method was significantly lower than that determined by acid hydrolysis method. The totalfat content in tea determined by acid hydrolysis method was consistent with the total amount of fatty acids determined by gas chromatography, and their content conformed to the logical relationshipsimultaneously. The totalfat content in tea ranged from 0.6 to 4.1 g/100 g, which in green tea, white tea, yellow tea, and black tea were 2.2, 1.8, 1.6 and 0.6 g/100 g, respectively. The content of free fat in tea was less than 58%, with 42%-80% of the fat existing in a bound form. The fatty acids in tea were mainly unsaturated fatty acids, accounting for 67.52%-99.03% of the total fatty acids. There were differences in the composition of fatty acids in different types of tea, with the proportion of unsaturated fatty acids in yellow tea accounting for 98.84% of the total fatty acids, which was significantly higher than that of green tea, white tea, and black tea. The fatty acids with high content in green tea(except Tang chi xiaolan tea, Bawangjian green tea and Liuxi yuye tea)were α-linoleic acid, linoleic acid, and palmitic acid.

CONCLUSION

Theacid hydrolysis method is more suitable for the determination of fat in tea samples. The composition and content of fat and fatty acids in tea vary depending onfactors such as the type of tea and the degree of fermentation.

Evaluation of alternative gas chromatographic and mass spectrometric behaviour of trimethylsilyl-derivatives of non-hydrolysed sulfated anabolic steroids

Sulfated metabolites have shown to have potential as long-term markers (LTMs) of anabolic-androgenic steroid (AAS) abuse. The compatibility of gas chromatography-mass spectrometry (GC-MS) with trimethylsilyl (TMS)-derivatives of non-hydrolysed sulfated steroids has been demonstrated, where, after derivatisation, generally, two closely eluting isomers are formed that both have the same molecular ion [M-H2 SO4 ]•+ . Sulfated reference standards are in limited commercial availability, and therefore, the current knowledge of the GC-MS behaviour of these compounds is mainly based on sulfating and analysing the available standard reference material. This procedure can unfortunately not cover all of the current known LTMs as these are often not available as pure substance. Therefore, in theory, some metabolites could be missed as they exhibit alternative behaviour. To investigate the matter, in-house sulfated reference materials that bear resemblance to known sulfated LTMs were analysed on GC-MS in their TMS-derivatised non-hydrolysed state. The (alternative) gas chromatographic and mass spectrometric behaviour was mapped, evaluated and linked to the corresponding steroid structures. Afterwards, using fraction collection, known sulfated LTMs were isolated from excretion urine to confirm the observed findings. The categories that were selected were mono-hydroxy-diones, 17-methyl-3,17-diols and 17-keto-3,16-diols as these are commonly encountered AAS conformations. The ability to predict the GC-MS behaviour of non-hydrolysed sulfated AAS metabolites is the corner stone of finding new metabolites. This knowledge is also essential, for example, for understanding AAS detection analyses, for the mass spectrometric characterization of metabolites of new designer steroids or when one needs to characterize an unknown steroid structure.

[Optimization and application of determination method of cholesterol in various dishes]

OBJECTIVE

To establish a rapid and accurate method for the determination of cholesterol in a variety of finished dishes.

METHODS

The samples were saponified with ethanol and potassium hydroxide solution at 80 ℃ for 0.5 h, then vortexed and mixed fully with ultrapure water, and extracted twice with 25 mL n-hexane. The extracting solution were evaporated to dryness under vacuum and redissolved by ethanol, finally determined by gas chromatograph. The sample loading solution was separated by HP-5 capillary column(30 m×0.25 mm, 0.25 μm) and quantified with external standard method.

RESULTS

The method had good linearity in the concentration range of 2.5-250 μg/mL for cholesterol and the correlation coefficient was 0.9999. The detection limit was 0.25 mg/100 g edible part, and the limit of quantification was 0.75 mg/100 g edible part. Three representative samples were picked for spiked recovery experiments with three concentration levels according to their content of cholesterol. The average recovery rates ranged from 91.1% to 101%, and the relative standard deviations were not more than 5%. The content range of cholesterol in 15 vegan dishes was from negative to 10.3 mg/100 g edible part, in 14 dishes contained meat and vegetable was from 2.34 to 80.2 mg/100 g edible part and in 9 pure meat dishes was from 25.4 to 288 mg/100 g edible part.

CONCLUSION

Compared with the national standard method, the method is simple to operate and more friendly to the experimenter while ensuring the accuracy and sensitivity requirements. It can meet the needs of efficient batch determination of cholesterol in a variety of finished dishes.

Unraveling the potential of breath and sweat VOC capture devices for human disease detection: a systematic-like review of canine olfaction and GC-MS analysis

The development of disease screening methods using biomedical detection dogs relies on the collection and analysis of body odors, particularly volatile organic compounds (VOCs) present in body fluids. To capture and analyze odors produced by the human body, numerous protocols and materials are used in forensics or medical studies. This paper provides an overview of sampling devices used to collect VOCs from sweat and exhaled air, for medical diagnostic purposes using canine olfaction and/or Gas Chromatography-Mass spectrometry (GC-MS). Canine olfaction and GC-MS are regarded as complementary tools, holding immense promise for detecting cancers and infectious diseases. However, existing literature lacks guidelines for selecting materials suitable for both canine olfaction and GC-MS. Hence, this review aims to address this gap and pave the way for efficient body odor sampling materials. The first section of the paper describes the materials utilized in training sniffing dogs, while the second section delves into the details of sampling devices and extraction techniques employed for exhaled air and sweat analysis using GC-MS. Finally, the paper proposes the development of an ideal sampling device tailored for detection purposes in the field of odorology. By bridging the knowledge gap, this study seeks to advance disease detection methodologies, harnessing the unique abilities of both dogs and GC-MS analysis in biomedical research.

Correction of the urinary testosterone to epitestosterone ratio measurement in antidoping analyses by chromatographic and mass spectrometric techniques

The ratio of testosterone (T) to epitestosterone (E) determined in urine samples is the main biomarker used to prove T and precursors abused by athletes. Analytically, the correction of the ratio is required by the World Anti-Doping Agency. This work describes a series of experiments aimed to study when it is appropriate to correct the T/E ratio value, using different mass spectrometric techniques since only reports on GC-MS exist. Analyses using external calibrators, controls, and routine samples were performed by three different techniques GC-MS, GC-MSn , and LC-MSn . A statistical comparison of the T/E was performed after the application of two corrections previously published: Isotopic contribution peak area correction (corr_1) and use of a verified internal deuterated internal standard (TD3/ED3) correction (corr_2) and the ratio based on T and E concentrations. The use of external calibration samples introduces biases that influence not only the T and E concentrations but also the T/E ratio, even when both methods of correction are applied. The correction after applying corr_1 method barely contributed to the accuracy of the T/E calculation. Nevertheless, the application of the corr_2 method increased the accuracy between 5% and 6% when comparing theoretical and experimental T/E values. Finally, the best results were obtained by the ratio calculated directly from the estimated concentrations of T and E. Attention must be paid when the T/E is measured by LC-MSn since different acquisition modes produced significantly different results, even in MS/MS when the same transition is used for T and E.

An Improved Validated Method for the Determination of Short-Chain Fatty Acids in Human Fecal Samples by Gas Chromatography with Flame Ionization Detection (GC-FID)

Short-chain fatty acids (SCFAs) are metabolites produced by the gut microbiota through the fermentation of non-digestible carbohydrates. Recent studies suggest that the gut microbiota composition, diet and metabolic status play an important role in the production of SCFAs. The primary objective of this study was to develop a simplified method for SCFA analysis in human fecal samples by gas chromatography with flame ionization detection (GC-FID). The secondary objective was to apply the method to fecal samples collected from a clinical trial. The developed GC-FID method showed excellent linearity (R2 > 0.99994), with a limit of detection (LOD) ranging from 0.02 to 0.23 µg/mL and a limit of quantification (LOQ) ranging from 0.08 to 0.78 µg/mL. Recovery for the method ranged between 54.24 ± 1.17% and 140.94 ± 2.10%. Intra- and inter-day repeatability ranged from 0.56 to 1.03 and from 0.10 to 4.76% RSD, respectively. Nine SCFAs were identified and quantified (acetic, propionic, iso-butyric, butyric, iso-valeric, valeric, 4-methyl valeric, hexanoic and heptanoic acids) in freeze-dried fecal samples. The clinical trial compared participants with prediabetes mellitus and insulin resistance (IR-group, n = 20) to metabolically healthy participants (reference group, R-group, n = 9) following a 4-week intervention of a daily red raspberry smoothie (RRB, 1 cup fresh-weight equivalent) with or without fructo-oligosaccharide (RRB + FOS, 1 cup RRB + 8 g FOS). The statistical analysis (Student's t-test, ANCOVA) was performed on PC-SAS 9.4 (SAS Institute). Acetic acid was higher in the R-group compared to the IR-group at baseline/week 0 (p = 0.14). No significant changes in fecal SCFA content were observed after 4 weeks of either RRB or RRB + FOS.

Optimising a urinary extraction method for non-targeted GC-MS metabolomics

Urine is ideal for non-targeted metabolomics, providing valuable insights into normal and pathological cellular processes. Optimal extraction is critical since non-targeted metabolomics aims to analyse various compound classes. Here, we optimised a low-volume urine preparation procedure for non-targeted GC-MS. Five extraction methods (four organic acid [OA] extraction variations and a "direct analysis" [DA] approach) were assessed based on repeatability, metabolome coverage, and metabolite recovery. The DA method exhibited superior repeatability, and achieved the highest metabolome coverage, detecting 91 unique metabolites from multiple compound classes comparatively. Conversely, OA methods may not be suitable for all non-targeted metabolomics applications due to their bias toward a specific compound class. In accordance, the OA methods demonstrated limitations, with lower compound recovery and a higher percentage of undetected compounds. The DA method was further improved by incorporating an additional drying step between two-step derivatization but did not benefit from urease sample pre-treatment. Overall, this study establishes an improved low-volume urine preparation approach for future non-targeted urine metabolomics applications using GC-MS. Our findings contribute to advancing the field of metabolomics and enable efficient, comprehensive analysis of urinary metabolites, which could facilitate more accurate disease diagnosis or biomarker discovery.

Allergens and Other Harmful Substances in Hydroalcoholic Gels: Compliance with Current Regulation

Hydroalcoholic gels or hand sanitisers have become essential products to prevent and mitigate the transmission of COVID-19. Depending on their use, they can be classified as cosmetics (cleaning the skin) or biocides (with antimicrobial effects). The aim of this work was to determine sixty personal care products frequently found in cosmetic formulations, including fragrance allergens, synthetic musks, preservatives and plasticisers, in hydroalcoholic gels and evaluate their compliance with the current regulation. A simple and fast analytical methodology based on solid-phase microextraction followed by gas chromatography-tandem mass spectrometry (SPME-GC-MS/MS) was validated and applied to 67 real samples. Among the 60 target compounds, 47 of them were found in the analysed hand sanitisers, highlighting the high number of fragrance allergens (up to 23) at concentrations of up to 32,458 μg g-1. Most of the samples did not comply with the labelling requirements of the EU Regulation No 1223/2009, and some of them even contained compounds banned in cosmetic products such as plasticisers. Method sustainability was also evaluated using the metric tool AGREEPrep, demonstrating its greenness.