HS-GC MS Research Articles

Long-term escape behavior and release mechanism of organic emissions from asphalt materials

In the context of carbon neutrality and carbon peaking, investigating the long-term escape behavior and release mechanism of organic emissions from asphalt materials can contribute to the development of environmentally sustainable asphalt pavements. In this study, the long-term emission behavior and release mechanism of organic emissions from asphalt materials were unraveled by combining the headspace gas chromatography–mass spectrometry (HS-GC–MS), differential scanning calorimetry (DSC), fluorescence microscopy (FM), and Fourier transform infrared spectroscopy (FTIR) tests. The results demonstrate that the pressure aging vessel (PAV) test and the ultraviolet (UV) aging test can result in a notable reduction in the concentration of organic emissions from asphalt materials, respectively. This indicates that asphalt pavements can potentially release a substantial quantity of organic emissions during their long-term service life. Besides, the aging mechanism of asphalt materials is established to unravel the release mechanism of organic emissions from asphalt materials. Aging increases the probability of organic emissions being released and volatilized from asphalt materials, which leads to the organic emissions from asphalt materials being more likely to be released and volatilized. Consequently, the aging process facilitates a greater release and volatilization of organic emissions from asphalt materials, resulting in a decrease in the detected concentration of these emissions after aging.

Validation and Collaborative Studies of Headspace Gas Chromatography-Mass Spectrometry for Determination of 1,4-Dioxane in Cosmetic Samples

Abstract Background 1,4-Dioxane (1,4-D) is a byproduct of the synthesis of surfactants, typically found in some cosmetics products such as shampoo, toothpaste, and soap. The presence of 1,4-D in cosmetics products is limited to a certain amount since 1,4-D is classified as a probable human carcinogen. Objective This present study was intended to validate static headspace gas chromatography-mass spectrometry (HS GC-MS) for the determination of 1,4-D in cosmetics products. Methods The condition of HS and GC-MS was optimized to get the best condition for analysis of 1,4-D using 1,4-dioxane-d8 (1,4-D-d8) as internal standard (IS). The developed method was validated by evaluating the key performance characteristics, including specificity, linearity, limit of detection (LoD), limit of quantification (LoQ), accuracy, and precision. Results The results showed that HS GC-MS was specific since the peaks of the selected ion monitoring (SIM) mode could be separated and confirmed at m/z 88 and m/z 96 for 1,4-D and 1,4-D-d8, respectively. The method was linear over the concentration range of 0.1287–1.2875 µg/mL, with R2 > 0.999 and RSD residuals <2.0. A collaborative study was conducted on this method, with 10 participating laboratories from four countries. The outcome of this study was found to be accurate and precise, as evidenced by the excellent recoveries ranging from 94.6% to 102.1%, and with good reproducibility with RSD values ranging from 0.2 to 1.1%. The collaborative studies exhibited that all data reported by 10 participating laboratories in four countries were inliers without any extreme values observed either in mean or RSD values Conclusions HS GC-MS is found to be fit and suitable for the determination of trace level of 1,4-D in cosmetics products. Highlights The HS GC-MS method could be proposed as a standard method for quantitative analysis of 1,4-D in cosmetics products since the collaborative studies indicated that the developed method meet the requirement in “Guidelines for Collaborative Study Procedures to Validate Characteristics of a Method of Analysis.”

Quantitative determination of nitrous oxide in human blood by HS-GC–MS: forensic application of two fatal poisoning cases

Nitrous oxide (N2O), also known as laughing gas, has a euphoric effect and is becoming increasingly popular as a recreational inhalant drug. Deaths caused by recreational nitrous oxide abuse are rare, but may still occur. Although some methods for the quantification of N2O by GC-MS have been reported, elimination of carbon dioxide interference and the choice of a suitable internal standard remain current limitations to accurate N2O quantification. Here, a validated method using headspace-gas chromatography–mass spectrometry (HS-GC–MS) is described that allows the quantification of N2O in human blood samples: sodium hydroxide is used to remove carbon dioxide, and n-pentane is chosen as a suitable internal standard. Collectively, the validation results show a good linear relationship of N2O in blood within the concentration range of 0.02 ∼ 0.5 mL/mL and an LOD of 0.005 mL/mL. Subsequent application of the validated method to two real mortality cases due to N2O intoxication provided reference values for blood concentrations in forensic cases. Other biological specimens (gaseous samples and tissues) of the deceased were also analyzed to demonstrate that the deaths were caused by asphyxia due to the inhalation of N2O.

Optimization of a carbon adsorption/HS-GC–MS method for ignitable liquids classification from fire debris

The main goal of any fire investigation is to find the origin and cause of fire. Fire is commonly initiated or accelerated by using ignitable liquids (ILs). The analysis of fire debris can contribute to the determination of the origin of the fire. In this study, the thermal desorption of IL residues (ILRs) from activated charcoal strips (ACS) was optimized prior to headspace- gas chromatography- mass spectrometry (HS-GC–MS) analysis for the identification and classification of ILRs in fire debris samples. A Box-Behnken Design (BBD) coupled with Response Surface Methodology (RSM) were used to determine the optimized conditions in the following ranges: incubation temperature (80–140 ˚C), incubation time (30–60 min), and agitation speed (250–750 rpm). The sum of the differences between the total ion spectrum (TIS) of gasoline and diesel was used as dependent variables. The quadratic model was significant with a p- value of 0.0061 and a coefficient of determination equals to 0.911. RSM revealed that an increase in incubation temperature and agitation speed increases the response. The optimized conditions were 140 °C and 750 rpm. Further optimization of the incubation time was studied by analyzing fire debris samples at different times (5–30 min) and 5 min was determined as the optimum condition. The final optimized conditions were applied in combination with chemometrics for the characterization of fire debris samples burned with different ILs. The obtained results demonstrate the feasibility of the method in fire debris analysis which avoids the use of organic solvents providing a greener and faster alternative method.

Comparative analysis of volatile fingerprints between different geographical origins and ornamental cultivars of white standard Chrysanthemum (Dendranthema grandiflorum)

BackgroundWhite standard Dendranthema grandiflorum (D. grandiflorum) is widely used for ornamental purposes. The volatile organic components (VOCs) of D. grandiflorum vary depending on the geographical origin and cultivar, which influence the market value. Here, we applied headspace extraction coupled with gas chromatography–mass spectrometry (HS–GC–MS) for the first time to determine the different origins (Korea, China, Vietnam) of D. grandiflorum in three genotypes (Baekgang, Jinba, Iwa-no-hakusen) based on volatile fingerprints and to assess the correlation among the metabolites identified in Korean and non-Korean D. grandiflorum.ResultsA total of 41 VOCs, mainly monoterpenoids, sesquiterpenoids, alcohols, and fatty acids, were identified. Principal component analysis showed that instead of geographical origin, genotype influences D. grandiflorum fingerprints. Cultivar discrimination was mainly affected by the metabolites associated with the alpha-terpinyl cation pathway. The orthogonal partial least squares discriminant analysis model achieved 100% and 93.3% accuracies in the calibration and validation sets, respectively. The results of volcano plots and clustering analysis, sesquiterpenoids were significantly more abundant in non-Korean than in Korean, whereas monoterpenoids were abundant in Korean samples.Conclusions41 makers confirmed robustness maintenance over two years. These findings can be useful for reliably identifying the geographical origin of D. grandiflorum and providing a comprehensive understanding of VOCs in D. grandiflorum cultivars grown in different countries of origins.Graphical

Volatilome and flavor analyses based on e-nose combined with HS-GC-MS provide new insights into ploidy germplasm diversity in Platostoma palustre

Platostoma palustre (Mesona chinensis Benth or Hsian-tsao, also known as “Xiancao” in China), is an edible and medicinal plant native to India, Myanmar, and Indo-China. It is the main ingredient in the popular desserts Hsian-tsao tea, herbal jelly, and sweet herbal jelly soup. P. palustre is found abundantly in nutrient-rich substances and possesses unique aroma compounds. Variations in the contents of volatile compounds among different germplasms significantly affect the quality and flavor of P. palustre, causing contradiction in demand. This study investigates the variation in the volatile compound profiles of distinct ploidy germplasms of P. palustre by utilising headspace gas chromatography-mass spectrometry (HS-GC–MS) and an electronic nose (e-nose). The results showed significant differences in the aroma characteristics of stem and leaf samples in diverse P. palustre germplasms. A total of sixty-seven volatile compounds have been identified and divided into ten classes. Six volatile compounds (caryophyllene, α-bisabolol, benzaldehyde, β-selinene, β-elemene and acetic acid) were screened as potential marker volatile compounds to discriminate stems and leaves of P. palustre. In this study, leaves of P. palustre showed one odor pattern and stems showed two odor patterns under the influence of α-bisabolol, acetic acid, and butyrolactone. In addition, a correlation analysis was conducted on the main volatile compounds identified by HS-GC–MS and e-nose. This analysis provided additional insight into the variations among samples resulting from diverse germplasms. The present study provides a valuable volatilome, and flavor, and quality evaluation for P. palustre, as well as new insights and scientific basis for the development and use of P. palustre germplasm resources.

HS-GC–MS analysis of volatile organic compounds after hyperoxia-induced oxidative stress: a validation study

BackgroundExhaled volatile organic compounds (VOCs), particularly hydrocarbons from oxidative stress-induced lipid peroxidation, are associated with hyperoxia exposure. However, important heterogeneity amongst identified VOCs and concerns about their precise pathophysiological origins warrant translational studies assessing their validity as a marker of hyperoxia-induced oxidative stress. Therefore, this study sought to examine changes in VOCs previously associated with the oxidative stress response in hyperoxia-exposed lung epithelial cells.MethodsA549 alveolar epithelial cells were exposed to hyperoxia for 24 h, or to room air as normoxia controls, or hydrogen peroxide as oxidative-stress positive controls. VOCs were sampled from the headspace, analysed by gas chromatography coupled with mass spectrometry and compared by targeted and untargeted analyses. A secondary analysis of breath samples from a large cohort of critically ill adult patients assessed the association of identified VOCs with clinical oxygen exposure.ResultsFollowing cellular hyperoxia exposure, none of the targeted VOCs, previously proposed as breath markers of oxidative stress, were increased, and decane was significantly decreased. Untargeted analysis did not reveal novel identifiable hyperoxia-associated VOCs. Within the clinical cohort, three previously proposed breath markers of oxidative stress, hexane, octane, and decane had no real diagnostic value in discriminating patients exposed to hyperoxia.ConclusionsHyperoxia exposure of alveolar epithelial cells did not result in an increase in identifiable VOCs, whilst VOCs previously linked to oxidative stress were not associated with oxygen exposure in a cohort of critically ill patients. These findings suggest that the pathophysiological origin of previously proposed breath markers of oxidative stress is more complex than just oxidative stress from hyperoxia at the lung epithelial cellular level.

Detection of volatile organic compounds in airtight exhibition spaces by GC–MS using two complementary injection techniques

A novel method was developed and optimized for the determination of volatile organic compounds (VOCs) inside an airtight exhibition case used for the storage and display of museum artifacts. The method uses a static headspace module coupled to a gas chromatograph/mass spectrometer. In this method, the air is sampled by passive samplers (coconut shell charcoal and synthetic charcoal). In the laboratory, the VOCs are thermally desorbed (120 min, 60 °C) in the HS furnace after the addition of a small volume of dimethylacetamide (DMA). The VOCs present in the gas phase are then automatically analyzed by GC–MS. The information obtained is complemented by the analysis of the DMA liquid phase by direct injection GC–MS in the same chromatograph. The VOCs are identified by studying the mass spectra obtained by both techniques. This approach provides an economically viable, non-invasive and visually non-disruptive solution for VOC detection in enclosed spaces in museum environments. The use of two complementary injection techniques allows for good detection and suitable chromatographic response to a wide range of volatile compounds. This method was applied for the identification of VOCs present in an enclosed airtight exhibition case at the Museu Nacional d'Art de Catalunya (MNAC), where the formation of efflorescence was observed on the surface of a Modernist jewel displayed inside, as it was suspected that VOCs were the main cause for the degradation. Forty-five different VOCs were detected and identified inside the exhibition case: thirteen of them by HS–GC–MS, fifteen of them by direct injection GC–MS, and seventeen by both techniques. Among the most relevant VOCs identified, acetic acid, acetaldehyde and formaldehyde stand out due to the danger they pose to museum artifacts exposed in enclosed spaces, especially in the long term.

A straightforward method for determination of the sevoflurane metabolite hexafluoroisopropanol in urinary occupational medical samples by headspace-gas chromatography mass spectrometry

Biological monitoring of the unmodified sevoflurane and its metabolite hexafluoroisopropanol (HFIP) in urine samples was proposed to determine the individual exposure levels of the medical staff. In this study, a method for simultaneous determination of both compounds in urine using static headspace–gas chromatography-mass spectrometry (HS–GC–MS) was developed. The method is linear over a broad concentration range from 1 to 1000 µg/L (r2 > 0.999) and shows high precision. Limits of quantification (LOQ) are 0.6 µg/L for sevoflurane and 3 µg/L for HFIP, representing an excellent sensitivity without the necessity of analyte enrichment. The method was successfully applied in a German pilot-study to monitor both compounds in samples from medical personnel working in operating theatres. Urinary concentrations of HFIP ranged between < LOQ and 145 µg/L, while sevoflurane was below the LOD in all samples.

A non-invasive and rapid method for discrimination of inkjet printouts by ion mobility spectrometry combined with chemometrics

The identification and differentiation of inkjet printouts can be important to establish the authenticity of questioned documents during judicial processes. In this work, we developed an analytical method based on ion mobility spectrometry (IMS) combined with chemometrics to identify inkjet printouts for rapid on-site detection. The characteristic peaks in IMS spectra were first identified by HS–GC–MS which showed the chemical differences between inkjet printouts. To achieve further differentiation of the inkjet printouts, principal component analysis (PCA) was performed. The results demonstrated that they can grouped based on the types of inks used, regardless of the printer type and the aging time of the document. For accurate discrimination of inkjet printed documents, a supervised model based on orthogonal partial least square discriminant analysis (OPLS-DA) was developed, which provided good quality (R2Y = 0.954, Q2 = 0.953). The model gave excellent accuracy by correctly classifying 99.37% of the validation set (159 samples). Furthermore, the partial least squares (PLS) models were applied to predict the formation time of documents. A combination of Orthogonal signal correction (OCS) combined and discrete wavelet transform (DWT) was used for data processing showing the best performance for the PLS model. It provided satisfactory predictions for inkjet printouts over 7-1446 days aging time. IMS combined with chemometrics was confirmed to be feasible and accurate for questioned documents identification and can be further applied in solving actual cases.

Activity of volatiles induced by microbes and natural plants stifled the growth of Pythium aphanidermatum - the damping off in Tomato

BackgroundVolatilomes from natural plants and microbes imparts diverse antifungal properties to suppress the growth of plant pathogens and therefore can be a suitable alternative of chemical fungicides. The present experiment was to study effect of volatiles produced by natural plants and microbes on the fungal growth of Pythium aphanidermatum, which is a tomato seedling pathogen.ResultsIsolate of P. aphanidermatum, causing damping off in tomato were isolated and incubated at 25 ± 2 °C. The isolate was tested for the anti-oomycetes activities of volatiles in vitro. The volatiles produced by the leaves of Mentha spicata and Cymbopogon citratus showed the maximum inhibitory effect of 45.56 and 24.70 percent, respectively on the mycelial growth of P. aphanidermatum, whereas, the pathogen was not inhibited on exposure to the volatiles of macro-basidiomycetes fungi. The volatiles of T. asperellum showed the maximum inhibitory effect of 69.26 percent against P. aphanidermatum. The study also included the identification of Volatile Organic Compounds (VOCs) involved in the suppression of pathogens by Headspace Gas Chromatography Mass Spectrometry (HS GCMS). The results revealed the production of carvone by the leaves of M. spicata; citronellol and geraniol by C. citratus; isopentyl alcohol and limonene by T. asperellum with increased peak area percentage and these compounds possessed antifungal properties. The vaporous action of isopentyl alcohol completely suppressed the mycelial growth of P. aphanidermatum, which is highly correlated to the T. asperellum extract on pathogenic growth. While the compounds, carvone, and citronellol showed the maximum inhibitory effect of 89.02 and 85.49 percent, respectively when used at 500 ppm and also altered the sporulation behavior of P. aphanidermatum.ConclusionResults showed that volatiles of M. spicata and T. asperellum have anti-oomycetes action on pathogenic growth leading to a distortion of sporulation of P. aphanidermatum. High antifungal properties make VOCs suitable for incorporation as a new integrated plant disease management programs.

Direct and efficient conversion of antibiotic wastewater into electricity by redox flow fuel cell based on photothermal synergistic effect

Antibiotic wastewater has caused serious environmental pollution and is hard to utilize. Thus, it is urgent to develop a green and efficient technology for treating antibiotic wastewater and effective utilization. The reported fuel cell technologies can degrade antibiotics and generate electricity simultaneously, but their cell performance is very bad and difficult application. Herein, we reported a new environment-friendly and low-cost redox flow fuel cell (RFFC) based on the photothermal synergistic effect to convert antibiotic wastewater into electricity directly and efficiently at low temperature. The developed RFFC can output the maximum power density of 98.2 mW cm−2 which is 545 times of the reported microbial fuel cells and 270 times of the reported photocatalytic fuel cells. And the photothermal degradation method is better than the thermal degradation and photo degradation. Furthermore, it can discharge stably >2.5 h at high current density of 2 A cm−2 and successfully power a small electrical fan (1.5 V). The reaction mechanism is studied by the density functional theory (DFT) calculation, and the results show that FeCl3 molecules as photocatalyst and electron carriers of the RFFC can complex with antibiotics to greatly reduce the energy gap between HOMO and LUMO of antibiotics, which make the antibiotic molecules easy to be excited to unstable excited state by visible and UV light (λ < 733 nm) and greatly beneficial for their photothermal degradation. Besides, when using cefuroxime sodium wastewater as the model wastewater, HS-GC–MS results show that cefuroxime sodium can be completely degraded into non-toxic micro molecules after generating electricity. This work shows promising potential application for high-value utilization of antibiotic wastewater and generating clean electricity.

From volatiles to solid wastes: Towards the full valorization of lavender and rosemary by simultaneous in situ microwaves and ultrasounds irradiation extraction

Novel green extractions aim at the full valorization of aromatic herbs along with the minimization of energy consumption, extraction time and cost of the processes. In this perspective, a simultaneous ultrasound and microwave irradiation extraction method (US-IMWAE) for the full valorization of aromatic herbs is here presented. This green approach has been applied to the isolation of essential oils (EOs), hydrosols and solid residues from lavender and rosemary plants. The yields of US-IMWAE in terms of EO weight percentage (wt%), polyphenols concentration and thermochemical characteristics of the solid residues have been compared with microwave assisted extraction (IMWAE) and hydrodistillation (HD). The composition profiles of EOs and hydrosols have been analyzed and quantified by head space gas chromatography mass spectrometry (HS-GC–MS), liquid chromatography with UV/visible diode array/fluorescence detector (HPLC-DAD-FD) and the Folin-Ciocalteu test for the total phenolic content (TPC). Solid residues as valuable by-products have been investigated by FTIR spectroscopy in tandem with chemometrics, thermogravimetric analysis (TGA) and combustion calorimetry. We found that the US-IMWAE green extraction method has produced higher yields of EOs with appealing composition profiles for cosmetic, fragrance and perfume industries (lavender), and for pharmacology and medical applications (rosemary). The high concentration of rosmarinic acid and the total phenolic content in hydrosols obtained with the US-IMWAE method, highlights its great potential. Chemometric analysis of solid residues has found that cellulose is the main component followed by hemicellulose and lignin. The experimental values of enthalpy of combustion of the solid residues (ΔcH) match with the corresponding calculated values and confirm their energetic features and their potential uses as alternative biomass for fuel production. US-IMWAE is environmentally friendly, highly flexible, controllable, and it enables to break the scale-up barrier in ultrasounds and microwave assisted industrial processes. Thus, US-IMWAE has a great potential to reduce EO production costs, and to increase local farm income through the full exploitation of aromatic herbs.

μ-Raman Determination of Essential Oils' Constituents from Distillates and Leaf Glands of Origanum Plants.

A novel, inexpensive and simple experimental setup for collecting μ-Raman spectra of volatile liquids in very small quantities was developed. It takes advantage of capillary forces to detain minute volatile liquid volumes. Spectra of volatile and even scattering or absorbing media can be measured more effectively. The method is used to facilitate the collection of intensity-consistent Raman spectra from a series of reference compounds present in Origanum essential oils, in order to quantify their constituents by multiple linear regression. Wild grown Origanum plants, collected from five different regions in Greece and taxonomically identified as O. onites, O. vulgare subsp. hirtum and O. vulgare subsp. vulgare, were appropriately distilled to acquire their essential oils. Comparison of the Raman results with those from headspace gas chromatography-mass spectrometry (HS GC-MS) confirmed the successful relative quantification of the most abundant essential oil constituents, highlighting the similarities and differences of the three Origanum taxa examined. Finally, it is demonstrated that directly measuring the leaf peltate glandular hairs yields exploitable results to identify the main components of the essential oil they contain, underlining the potential of in situ (field or industry) measurements utilizing microscope-equipped portable Raman spectrometers.

Characterization of odors and volatile organic compounds changes to recycled high-density polyethylene through mechanical recycling

The application of post-consumer recycled (PCR) plastics is gaining growing attention, yet, the residual odor of recycled plastics hinders its application. In current study, electronic nose (E-nose), headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), and headspace-gas chromatography-mass spectrometry (HS-GC–MS) combined with multiple chemometrics methods were analyzed to obtain different information of VOCs in rHDPE. In the meantime, the potential influence of the re-granulation process on VOCs was investigated. Relative odor activity values (ROAV) was applied to distinguish characteristic odors description of HDPE pellets in different manufacturers. Results showed that the established fingerprinting of VOCs based on HS-GC-IMS could provide an effective means for rapidly identifying rHDPE plastics. The more substantial amounts of VOCs in rHDPE flakes and pellets are terpenes and aliphatic hydrocarbons. Although the re-granulation process effectively removed most of the VOCs remaining in the washing process, acids, aromatic hydrocarbons, and terpenes were potentially residual in the rHDPE pellets. It was also revealed that terpenes and acids were the volatile odor compounds in most rHDPE pellets. Both d-limonene and octanal are the main key compounds of rHDPE pellets because of their maximum contribution to the overall odor, and together with other key odor compounds with similar odor, form the characteristic odor of citrus, sweet, and floral.

A closer look at the synthesis of 2-[18F]fluoroethyl tosylate to minimize the formation of volatile side-products

Background2-[18F]Fluoroethyltosylate ([18F]FEtOTs) is a well-known 18F-fluoroalkylating agent widely used to synthesize radiotracers for positron emission tomography. The widespread use of [18F]FEtOTs is due in part to its low volatility when compared to other halide and sulfonate building blocks. In this work, the radioactive volatile side-products formed during the synthesis of [18F]FEtOTs were identified and characterized for the first time, and an optimization of the reaction conditions to minimize their formation was proposed.ResultsIn order to characterize the volatiles produced during [18F]FEtOTs synthesis, the reaction mixtures of both cold FEtOTs and [18F]FEtOTs were co-injected onto the HPLC system. The radioactive peaks corresponding to the volatile compounds were collected, analyzed through headspace gas chromatography mass spectrometry sampler (HS-GC–MS) and identified as vinyl fluoride ([19F]VF) and 2-fluoroethanol ([19F]FEOH). By using a rotatable central composite design with a two-level full factorial core of two factors (22), it was determined that temperature and time are independent variables which affect the generation of [18F]VF and [18F]FEOH during the radiosynthesis of [18F]FEtOTs. In addition, in order to reduce the formation of the volatiles ([18F]VF and [18F]FEOH) and increase the yield of [18F]FEtOTs, it was demonstrated that the molar ratio of base to precursor must also be considered.Conclusion[18F]VF and [18F]FEOH are volatile side-products formed during the radiosynthesis of [18F]FEtOTs, whose yields depend on the reaction time, temperature, and the molar ratio of base to precursor. Therefore, special care should be taken during the radiosynthesis and subsequent reactions using [18F]FEOTs in order to avoid environmental contamination and to improve the yield of the desired products.

Investigation of sulfur-containing compounds in spears of green and white Asparagus officinalis through LC-MS and HS-GC–MS

Asparagus officinalis is largely consumed as food in many parts of the world, and due to its content in secondary metabolites can be considered as a vegetable with health-promoting value. Part of its organoleptic qualities can be ascribed to the presence of sulfur-containing compounds, nevertheless qualitative data about the volatile and non-volatile pools of these compounds in green and white spears of asparagus are poorly investigated. Due to the wide alimentary use of this crop and the potential biological properties of S-containing compounds, research aimed at filling this gap is required. In this paper, a comprehensive characterization of S-metabolites in asparagus performed by LC-MS and GC–MS is reported. Both green and white varieties of asparagus were considered. The fresh vegetal material was subjected to different sample preparation procedures, such as solvent extraction, distillation, and headspace sampling. Furthermore, a derivatization protocol with 4,4′-dithiodipyridine was used for low-molecular weight thiols, and both derivatized and underivatized compounds were analysed by LC-MS. The methods allowed to identify 80 S-containing metabolites in asparagus samples, and to assess the distribution of these compounds in different parts of the spears. Results were discussed comparing the literature, and the identified compounds were considered to explain some peculiar taste and odorous properties of green and white asparagus, although further research is required to confirm our hypotheses.Overall, in this work we report for the first time an exhaustive characterization of S-compounds profile in spears of green and white Asparagus varieties. Furthermore, results indicate that multiple approaches should be used to study the S-containing metabolites of this plant, due to their diverse chemical properties.

Oxidation reaction and thermal stability of 1,3-butadiene under oxygen and initiator

1,3-Butadiene is the simplest conjugated diene, which is widely used in polymer materials, organic synthesis, and other fields. The investigation of its thermal stability and oxidation characteristics is necessary for production, transportation, and use safety. The pressure and temperature behavior of the autoxidation reaction of 1,3-butadiene with oxygen were determined using a custom-designed mini closed pressure vessel test (MCPVT). The effects of free radical initiators CHP and AIBN on the oxidation reaction were investigated. The thermal decomposition characteristics of oxidation products were measured by differential scanning calorimetry (DSC), and its hazards were discussed. The results showed that the oxidation reaction of 1,3-butadiene was easy to occur. Moreover, the activation energies of autoxidation, CHP-initiated oxidation, and AIBN-initiated oxidation reaction were 20.85 kJ·mol−1, 33.30 kJ·mol−1, and 56.27 kJ·mol−1, respectively. In addition, the oxidation products were analyzed by headspace sampler-gas chromatography-mass spectrometry (HS-GC–MS), GC–MS, and iodometry. Some of 1,3-butadiene oxidation products under three conditions are the same, for example, 3-butene-1,2-diol, 4-vinylcyclohexene, 2(5H)-furanone, 2-propen-1-ol, and 2,6-cyclooctadien-1-ol. According to the reaction products, the oxidation reaction pathway of 1,3-butadiene was described. The research results are significant for avoiding fire and explosion accidents in the production, transportation, and application of 1,3-butadiene.

Headspace GC/MS and fast GC e-nose combined with chemometric analysis to identify the varieties and geographical origins of ginger (Zingiber officinale Roscoe)

Food authenticity regarding different varieties and geographical origins is increasingly becoming a concern for consumers. In this study, headspace gas chromatography-mass spectrometry (HS-GC–MS) and fast gas chromatography electronic nose (fast GC e-nose) were used to successfully distinguish the varieties and geographical origins of dried gingers from seven major production areas in China. By chemometric analysis, a distinct separation between the two varieties of ginger was achieved based on HS-GC–MS. Furthermore, flavor information extracted by fast GC e-nose realized the discrimination of geographical origins, and some potential flavor components were selected as important factors for origin certification. Moreover, several pattern recognition algorithms were compared in varietal and regional identification, and random forest (RF) led to the highest accuracies for discrimination. Overall, a rapid and precise method combining multivariate chemometrics and algorithms was developed to determine varieties and geographical origins of ginger, and it could also be applied to other agricultural products.

Similarity network fusion for aggregating headspace GC–MS and direct analysis in real time–mass spectrometry data from solid samples to enhance species identification efficiency of high–temperature heated wood

Pterocarpus santalinus and Pterocarpus tinctorius are commonly used species of the genus Pterocarpus in the wood trade. Although both of them have been listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) since 2019, it is still critical to identify them in terms of plant taxonomy. Currently, high-temperature heating is an accepted treatment method for high-density wood species such as Pterocarpus to improve dimensional stability and restore previous drying defects partially. It has proved challenging to identify the high-temperature (e.g., 120 °C) heated wood from these two species. Thus, this study approaches species identification of two Pterocarpus of high-temperature (e.g., 120 °C) heated solid wood samples using headspace–gas chromatography–mass spectrometry (HS–GC–MS). Besides, a computational analytical method named similarity network fusion (SNF) was proposed to aggregate data in two different types, respectively, derived from the HS–GC–MS and direct analysis in real time–mass spectrometry (DART–MS) to explore the feasibility of improving the efficiency and accuracy of wood species discrimination. The SNF exhibits more significant differences and higher predictive accuracy (100%) between P. santalinus and P. tinctorius than that based on the HS–GC–MS data (77.78%) or DART–MS (66.67%) alone. These results demonstrated the capability of the HS–GC–MS technique in the analysis of high-temperature heated solid wood and the potential of multidimensional or comprehensive data sets based on the SNF algorithm in the field of wood species identification.