GC qMS Research Articles

Identification of metabolite changes and evaluation of biological activities in edible flowers of Magnolia kobus at different developmental stages

BackgroundMagnolia kobus belongs to the Magnoliaceae family and the genus Magnolia. The flowers are widely used in herbal tea and dietary supplements. It is effectively used in traditional medicines and its chemical constituents have various biological activities, such as anti-obesity, antioxidant, anticancer, anti-inflammatory, and anti-hyperlipidaemic activities. The flower developmental process of M. kobus involves a complex regulatory network and is intensively related to the quality and relative composition of primary and secondary metabolites of the flower. Hence, the identification of metabolic changes during different developmental stages of the flower was important for enhancing organoleptic and nutritional characteristics. To our knowledge, to date, none of the studies has investigated the relationship between metabolic changes (primary and secondary metabolites) during different developmental stages of the M. kobus flower.ResultsThis study investigated metabolic changes in 47 hydrophilic and 13 lipophilic compounds and biological activities in Magnolia kobus flowers during four developmental stages. Metabolites were identified using HPLC, GC–qMS, and GC–TOFMS. Throughout flower development, metabolite accumulation showed significant differences based on metabolomics approaches. The dynamic changes of 21 differential metabolites occurred between the young and mature stages. Flower buds exhibited high levels of phenylpropanoids and phytosterols. The total phenolic and flavonoid contents were most abundant in the buds and decreased from the bud to the old stages. Flower bud extracts showed the most powerful effects in three antioxidant assays and antibacterial effects against 10 pathogenic bacterial strains.ConclusionsThese findings emphasise the value of M. kobus flower buds as an edible natural source and provide valuable insight into the metabolic changes that occur in M. kobus flowers during development.Graphical

Comprehensive characterization of speciated volatile organic compounds (VOCs), gas-phase and particle-phase intermediate- and semi-volatile volatility organic compounds (I/S-VOCs) from Chinese diesel trucks

We established the comprehensive emission profiles of organic compounds for typical Chinese diesel trucks. The profiles cover the entire volatility range, including speciated volatile organic compounds (VOCs), intermediate-volatility organic compounds (IVOCs), and semi-volatile organic compounds (SVOCs). The VOCs and I/SVOCs were analyzed by one-dimensional gas chromatography quadrupole mass spectrometry (GC qMS) and two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-ToF-MS) separately. The impacts of starting mode and aftertreatment technology on the VOC, gaseous and particulate I/SVOC emissions, and the gas-particle partitioning were investigated. The emission factor (EF) of gas phase I/SVOCs was approximately 10 times higher than that of particle phase I/SVOCs and the chemical compositions and volatility distributions varied greatly. VOC, IVOC, and SVOC emissions significantly decreased when vehicles were equipped with advanced aftertreatment technologies. Diesel particulate filters (DPF) can remove >71 % VOC, 74 % gaseous, and 88 % particulate I/SVOCs, many of which are significant secondary organic aerosol (SOA) precursors. The chemical compositions and volatility distributions of the gaseous I/SVOCs and unburned diesel fuel were similar, revealing that diesel fuel is the main origin of the gaseous I/SVOCs. The I/SVOC emission profiles covering the whole volatility range, i.e., log10C* = −3 to 10 (C*: effective saturation concentration, μg m−3) were established.

Phytochemical Constituents and Antiproliferative Activities of Essential Oils from Four Varieties of Malaysian Zingiber officinale Roscoe against Human Cervical Cancer Cell Line.

This study evaluates the volatile metabolic constituents and anticancer potential of essential oils distilled from the rhizomes of four Malaysian Zingiber officinale Roscoe (Zingiberaceae family) varieties (Bentong (BE), Cameron Highlands (CH), Sabah (SA), and Bara (BA)). The ginger essential oils were analyzed by gas chromatography coupled with quadrupole mass spectrometry (GC qMS). A total of 58 secondary compounds were tentatively identified, representing 82.6–87.4% of the total ion count. These metabolites comprise mainly of monoterpene hydrocarbons (19.7–25.5%), oxygenated monoterpenes (23.6–33.7%), sesquiterpene hydrocarbons (21.3–35.6%), oxygenated sesquiterpenes (1.5–3.9%), and other minor classes of compounds (0.7–2.7%). Principal component analysis (PCA) enabled differentiation of the analyzed ginger essential oils according to their varieties, with respect to their metabolites and relative quantities. The antiproliferative activity against the HeLa cervical cancer cell line was investigated via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The oils were found to exhibit strong antiproliferative activities with IC50 values of 23.8, 35.3, 41.3, and 42.5 μg/mL for BA, BE, SA, and CH, respectively. These findings suggest that the differences among the secondary metabolites and their abundance in different varieties of Z. officinale essential oils appear to be related to their antiproliferative potential. The strong antiproliferative effects of these oils signified their potential in the prevention and chemotherapy of cervical carcinoma treatment.

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

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

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

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

An integrative approach based on GC-qMS and NMR metabolomics data as a comprehensive strategy to search potential breast cancer biomarkers.

Globally, breast cancer (BC) is leading at the top of women's diseases and, as a multifactorial disease, there is the need for the development of new approaches to aid clinicians on monitoring BC treatments. In this sense, metabolomic studies have become an essential tool allowing the establishment of interdependency among metabolites in biological samples. The combination of nuclear magnetic resonance (NMR) and gas chromatography-quadrupole mass spectrometry (GC-qMS) based metabolomic analyses of urine and breast tissue samples from BC patients and cancer-free individuals was used. Multivariate statistical tools were used in order to obtain a panel of metabolites that could discriminate malignant from healthy status assisting in the diagnostic field. Urine samples (n = 30), cancer tissues (n = 30) were collected from BC patients, cancer-free tissues were resected outside the tumor margin from the same donors (n = 30) while cancer-free urine samples (n = 40) where obtained from healthy subjects and analysed by NMR and GC-qMS methodologies. The orthogonal partial least square discriminant analysis model showed a clear separation between BC patients and cancer-free subjects for both classes of samples. Specifically, for urine samples, the goodness of fit (R2Y) and predictive ability (Q2) was 0.946 and 0.910, respectively, whereas for tissue was 0.888 and 0.813, revealing a good predictable accuracy. The discrimination efficiency and accuracy of tissue and urine metabolites was ascertained by receiver operating characteristic curve analysis that allowed the identification of metabolites with high sensitivity and specificity. The metabolomic pathway analysis identified several dysregulated pathways in BC, including those related with lactate, valine, aspartate and glutamine metabolism. Additionally, correlations between urine and tissue metabolites were investigated and five metabolites (e.g. acetone, 3-hexanone, 4-heptanone, 2-methyl-5-(methylthio)-furan and acetate) were found to be significant using a dual platform approach. Overall, this study suggests that an improved metabolic profile combining NMR and GC-qMS may be useful to achieve more insights regarding the mechanisms underlying cancer.

Sexual Dimorphism of Metabolite Profiles in Pigs Depends on the Genetic Background.

The study aimed to investigate possible systematic effects in the basic underlying variability of individual metabolomic data. In this context, the extent of gender- and genotype-dependent differences reflected in the metabolic composition of three tissues in fattening pigs was determined. The 40 pigs belonged to the genotypes PIx(LWxGL) and PIxGL with gilts and boars, respectively. Blood and tissue samples from M. longissimus dorsi and liver were directly taken at the slaughtering plant and directed to GC × GC qMS metabolite analysis. Differences were observed for various metabolite classes like amino acids, fatty acids, sugars, or organic acids. Gender-specific differences were much more pronounced than genotype-related differences, which could be due to the close genetic relation of the fattening pigs. However, the metabolic dimorphism between gilts and boars was found to be genotype-dependent, and vice versa metabolic differences between genotypes were found to be gender-dependent. Most interestingly, integration into metabolic pathways revealed different patterns for carbon (C) and nitrogen (N) usage in boars and gilts. We suppose a stronger N-recycling and increased energy metabolism in boars, whereas, in gilts, more N is presumably excreted and remaining carbon skeletons channeled into lipogenesis. Associations of metabolites to meat quality factors confirmed the applicability of metabolomics approaches for a better understanding about the impact of drivers (e.g., gender, age, breed) on physiological processes influencing meat quality. Due to the huge complexity of the drivers-traits-network, the derivation of independent biomarkers for meat quality prediction will hardly be possible.

Unraveling the Active Biomolecules Responsible for the Sustainable Synthesis of Nanoscale Silver Particles through Nuclear Magnetic Resonance Metabolomics

We have investigated the sustainable synthesis of silver nanoparticles (AgNPs) using blueberry (Vaccinium corymbosum L.) ethanolic extract from the point of view of the intervening metabolites. An extensive NMR metabolomic approach based on nuclear magnetic resonance (NMR) spectroscopy and headspace-solid phase microextraction (HS-SPME) followed by gas chromatography/quadrupole-mass spectrometry (GC–qMS) has been directed in order to ascertain for the first time the involved bioactive molecules as those responsible for the synthesis of AgNPs. The green process was monitored through UV–vis spectrophotometry, and a plethora of techniques such as EDX, XRD, XPS, TEM, SEM, and DLS were used to confirm the formation of the AgNPs. The successful synthesis was indirectly proven by their antibacterial activity against Gram-positive Streptococcus pyogenes and Gram-negative bacteria Salmonella typhi.

Formation of Two-Ring Aromatics in Hexylbenzene Pyrolysis

The formation of two-ring aromatics in hexylbenzene pyrolysis is used in this work as a model system toward understanding the underlying chemistry of coke formation during crude oil upgrading processes. In this work, batch reactor experiments were performed at 55 bar and 450 °C to study the pyrolysis of hexylbenzene utilizing two dimensional gas chromatography mass spectrometry (GC×GC–qMS) as an analysis tool. This work finds many different classes of aromatic species with more than one ring, including bridged two-ring aromatics, nonfully aromatized fused two-ring aromatics, fully aromatized fused two-ring aromatics, and >2-ring species. A kinetic model detailed with elementary chemical reactions is constructed using the reaction mechanism generator, with thermodynamic and kinetic parameters calculated by the CBS-QB3 quantum chemistry method. The results of the generated model were compared to batch reactor experiments. For many compounds, the predicted selectivities agree with the data within a factor of 2. The formation pathways of previously less-understood species were clarified based on evidence of intermediates predicted by the model and measured in this work’s experiments. Despite these advances, there are larger model-versus-data discrepancies in the selectivities of some species, and also, the overall conversion rate is underestimated, indicating the need for future work to further improve thermochemical and kinetics data of alkylaromatics.

Exploring a volatomic-based strategy for a fingerprinting approach of Vaccinium padifolium L. berries at different ripening stages

The effect of ripening on the evolution of the volatomic pattern from endemic Vaccinium padifolium L. (Uveira) berries was investigated using headspace-solid phase microextraction (HS-SPME) followed by gas chromatography/quadrupole-mass spectrometry (GC–qMS) and multivariate statistical analysis (MVA). The most significant HS-SPME parameters, namely fibre polymer, ionic strength and extraction time, were optimized in order to improve extraction efficiency. Under optimal experimental conditions (DVB/CAR/PDMS fibre coating, 40°C, 30min extraction time and 5g of sample amount), a total of 72 volatiles of different functionalities were isolated and identified. Terpenes followed by higher alcohols and esters were the predominant classes in the ripening stages – green, break and ripe. Although significant differences in the volatomic profiles at the three stages were obtained, cis-β-ocimene (2.0–40.0%), trans-2-hexenol (2.4–19.4%), cis-3-hexenol (2.5.16.4%), β-myrcene (1.9–13.8%), 1-hexanol (1.7–13.6%), 2-hexenal (0.7–8.0%), 2-heptanone (0.7–7.7%), and linalool (1.9–6.1%) were the main volatile compounds identified. Higher alcohols, carboxylic acids and ketones gradually increased during ripening, whereas monoterpenes significantly decreased. These trends were dominated by the higher alcohols (1-hexanol, cis-3-hexenol, trans-2-hexenol) and monoterpenes (β-myrcene, cis-β-ocimene and trans-β-ocimene). Partial least squares regression (PLSR) revealed that ethyl caprylate (1.000), trans-geraniol (0.995), ethyl isovalerate (−0.994) and benzyl carbinol (0.993) are the key variables that most contributed to the successful differentiation of Uveira berries according to ripening stage. To the best of our knowledge, no study has carried out on the volatomic composition of berries from endemic Uveira.

Discriminating Lacustrine and Marine Organic Matter Depositional Paleoenvironments of Brazilian Crude Oils Using Comprehensive Two-Dimensional Gas Chromatography–Quadrupole Mass Spectrometry and Supervised Classification Chemometric Approaches

The knowledge about the organic matter predominant depositional paleoenvironment in which crude oils gave rise is essential for the extensive understanding of their corresponding geochemical features. This task is laborious and conventionally performed through the extensive search for classical biomarkers contained in specific saturate, aromatic, resin, and asphaltene (SARA) fractions of the crude oils. In this work, the well-established analytical technique comprehensive two-dimensional gas chromatography–quadrupole mass spectrometry (GC × GC–QMS) was used to analyze the first two fractions (maltenes) of crude oils, performing the chromatographic data treatment with chemometrics to evaluate the lacustrine or marine predominant origin of the organic matter depositional paleoenvironment of the crude oils. In this approach, the extraction of the target information contained in the GC × GC–QMS data for discriminating between crude oils derived from lacustrine or marine organic matter environments was evaluat...

Impact of storage time and temperature on furanic derivatives formation in wines using microextraction by packed sorbent tandem with ultrahigh pressure liquid chromatography

This paper reports the effect of storage temperature, storage time and glucose content on furanic derivatives (FDs) formation in fortified Madeira wines using headspace solid phase microextraction (HS–SPME) combined with gas chromatography-quadrupole mass spectrometry (GC–qMS), and microextraction by packed sorbent (MEPS) tandem with ultrahigh pressure liquid chromatography coupled to photodiode array detection (UPLC–PDA). Based on the results obtained, MEPS/UPLC–PDA showed better FDs extraction compared to HS–SPME/GC–qMS, in terms of analysis reduction, sensitivity, reproducibility and allow detect all target furanic derivatives considered in this study. 5-Hydroxymethyl-2-furfural, one of the most abundant FDs in wines, is not detected by HS–SPME/GC–qMS, which suggest that this methodology is not the most suitable to achieve the purpose of this study.Regarding the impact of storage time and temperature on FDs formation using MEPS/UPLC–PDA, it was verified an increase on FDs concentration during storage time independently of storage temperature as well as glucose content, and this increase is also favored by temperature increases, being more significant at 55 °C. The results obtained in this study could be used as a useful tool in winemaking field in order to introduce changes in fermentation as well as baking (estufagem) process, and/or predict the effects of storage time by application of high temperatures.

Discriminating Brazilian crude oils using comprehensive two-dimensional gas chromatography–mass spectrometry and multiway principal component analysis

The geochemical characterization of petroleum is an essential task to develop new strategies and technologies when analyzing the commercial potential of crude oils for exploitation. Due to the chemical complexity of these samples, the use of modern analytical techniques along with multivariate exploratory data analysis approaches is an interesting strategy to extract relevant geochemical characteristics about the oils. In this work, important geochemical information obtained from crude oils from different production basins were obtained analyzing the maltene fraction of the oils by comprehensive two-dimensional gas chromatography coupled to quadrupole mass spectrometry (GC×GC–QMS), and performing multiway principal component analysis (MPCA) of the chromatographic data. The results showed that four MPC explained 93.57% of the data variance, expressing mainly the differences on the profiles of the saturated hydrocarbon fraction of the oils (C13-C18 and C19-C30n-alkanes and the pristane/phytane ratio). The MPC1 grouped the samples severely biodegraded oils, while the type of the depositional paleoenvironments of the oils and its oxidation conditions (as well as their thermal maturity) could be inferred analysing others relevant MPC. Additionally, considerations about the source of the oil samples was also possible based on the overall distribution of relevant biomarkers such as the phenanthrene derivatives, tri-, tetra- and pentacyclic terpanes.

Validation method of organochlorine pesticides residues in water using gas chromatography–quadruple mass

In analytical chemistry laboratories, it is critical to have a sensitive method to provide applicable qualitative and quantitative data. This research aimed to determine validated optimized method and acceptable Profession Test (PT) results of 18 organochlorine pesticides (OCPs) using gas chromatography operating with quadruple mass spectrophotometer (GC–QMS) and liquid–liquid extraction (LLE) technique. This will be used for acquiring accreditation and checking alternative instruments such as gas chromatography operational with flame ionization detector (GC–FID). Ismailia canal were selected to investigate organochlorine pesticides content in freshwater used for irrigation and drinking purposes.The obtained data for limit of quantification (LOQ) varied from 0.159 to 0.254 with Relative Standard Deviation (RSD%) below 20% (4.18–6.12). method detection limit (MDL) ranged from 0.04 to 0.08 μg/ml and squared correlation coefficient (R2) ranged from 0.9992 to 0.9999. The study concluded that application to real samples has been successfully assessed by optimized method.

Piston-cylinder based micro liquid–liquid extraction with GC–qMS for trace analysis of targeted chlorinated organic compounds in water

A fast and reliable approach for the measurement of sub parts-per-billion levels of targeted chlorinated compounds like tetrachloroethane, hexachloroethane, hexachlorobutadiene, pentachlorobenzene, and hexachlorobenzene in various water matrices such as waste water is described. The method employed a novel piston-cylinder-based micro liquid–liquid extraction technique using hexane as an extraction solvent. The device, known commercially as the MIXXOR, substantially accelerates extraction time by a factor of more than 100 times and reduces solvent consumption by a factor of 25 times when compared with the solvent extraction technique using wrist-action mechanical agitation. A recently introduced 6% cyanopropylphenyl –94% dimethylpolysiloxane capillary column offering a high degree of inertness was used for the separation of the analytes. A quadrupole mass spectrometer equipped with a triple-axis detector was also employed to enhance the instrument detection limit. With this technique, a complete separation for the analytes in water can be conducted in less than 10 min using a three-port SilFlow planar microfluidic device for back-flushing. Repeatability of retention times for all compounds were found to be less than 0.04% (n = 10). The compounds cited can be analyzed from 1 ng/mL to 10 μg/mL, with a detection limit and correlation coefficient of at least 0.5 ng/mL and 0.999, respectively. A relative precision of less than 1.2% relative standard deviation (RSD) (n = 20) at the 50 ng/mL level, with analyte recovery of greater than 99% (n = 3) from 10 ng/mL to 10 μg/mL, was obtained.

A Comparison of One-Dimensional and Comprehensive Two-Dimensional Gas Chromatography for Decomposition Odour Profiling Using Inter-Year Replicate Field Trials

Decomposition odour analysis involves the chemical profiling of volatile organic compounds produced by decomposing remains. This is important for areas of forensic science that rely on the detection of decomposition odour such as insect attraction to carrion, positive alerts of cadaver dogs to decomposing remains, and the development of field instrumentation for search and recovery procedures. Traditionally decomposition odour analysis has been performed using gas chromatography–quadrupole mass spectrometry (GC–qMS); however, the use of comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC×GC–TOFMS) is rapidly becoming more prevalent. The objective of this study was to compare GC–qMS and GC×GC–TOFMS for decomposition odour profiling based on inter-year replicate field studies using decomposing porcine remains. The increased peak capacity, sensitivity and selectivity afforded by GC×GC–TOFMS allowed peak co-elutions, chromatographic artefacts, and dynamic range to be more easily addressed and managed. Furthermore, the software associated with GC×GC–TOFMS provided several additional benefits including improved peak alignment between samples and increased consistency of reported results, overall allowing for additional statistical tests to be applied following data processing. Future GC–qMS results could be improved by implementing some of these software-associated procedures, potentially reducing the magnitude of variation observed between GC–qMS and GC×GC–TOFMS studies. One-dimensional GC analysis may also benefit substantially from coupling with TOFMS detection to provide an indirect increase in peak capacity using deconvolution. However, the wealth of information gained by using GC×GC–TOFMS in decomposition odour profiling is undoubtedly an asset in this field of research.

On the applicability of comprehensive two-dimensional gas chromatography combined with a fast-scanning quadrupole mass spectrometer for untargeted large-scale metabolomics

Comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC–MS) offers excellent chromatographic separation performance and superior sensitivity. As such, it is eminently suitable for the analysis of complex biological samples. The applicability of a GC×GC instrument equipped with a fast-scanning qMS detector for large-scale untargeted metabolome analyses was investigated. We optimized the dimensions of an apolar×medium-polar column combination in order to meet detector requirements and to compromise between separation performance and analysis time. The final method enabled a sufficient separation (R≥1.2 or higher) of approx. 90% of all analytes detected in urine within less than 1h. Using the qMS at maximum scan speed (20,000u/s) and choosing a scan range of m/z 60–550, a data acquisition frequency of 33Hz and usually at least 10–13 data points per 2D peak above the baseline were achieved. Peak area as well as peak height could thus be determined precisely (mean RSD 2.5%). Spectral skewing was limited regarding the data points covering the upper peak half. As a consequence, peak apex spectra could be used for the alignment of analytes in different samples. The linear dynamic range was 1–2.5 orders of magnitude, depending on the analyte. In addition, the slow transition into saturation beyond the linear dynamic range made it possible to exploit an extended “working range” for relative quantification. Long-term stability of the system was demonstrated by the analysis of more than 300 human urine study samples for which detailed repeatability and intermediate precision data are provided. In summary, the GC×GC–qMS system proved to be applicable for untargeted large scale metabolome analyses.

Octadecyl functionalized core–shell magnetic silica nanoparticle as a powerful nanocomposite sorbent to extract urinary volatile organic metabolites

In this present study, magnetic Fe3O4@SiO2 nanoparticles (MNPs) functionalized with octadecyl groups (Fe3O4@SiO2-C18 NPs) were synthesized, characterized and employed, for the first time, as powerful nanosorbent to extract endogenous volatile organic metabolites (EVOMs) namely, hexanal, heptanal, decanal, benzaldehyde, 4-heptanone, 5-methyl-2-furfural and phenol, described as potential biomarkers of cancer, from human urine. By using co-precipitation, surface modification methods, the carbon-ferromagnetic nanocomposite was synthesized and characterized by infrared spectrum (IR) and transmission electron microscopy (TEM). By coupling with gas chromatography–mass spectrometry (GC–qMS), a reliable, sensitive and cost-effective method was validated. To test the extraction efficiency of the carbon-ferromagnetic nanocomposite toward urinary EVOMs experimental variables affecting the extraction performance, including nanosorbent amount, adsorption time, elution time, and nature of elution solvent, were investigated in detail. The extraction process was performed by dispersing Fe3O4@SiO2-C18 NPs into working solution containing targeted VOMs, and into urine samples, and then eluted with an adequate organic solvent. The eluate was collected, concentrated and analyzed by GC–qMS. Under the optimized conditions, the LODs and LOQs achieved were in the range of 9.7–57.3 and 32.4–190.9ng/mL, respectively. Calibration curves were linear (r2≥0. 988) over the concentration ranges from 0.25 to 250ng/mL. In addition, a satisfying reproducibility was achieved by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) less than 3 and 11%, respectively. The method also afforded satisfactory results in terms of the matrix effect (72.8–96.1%) and recoveries (accuracy) higher than 75.1% for most of the studied EVOMs. The Fe3O4@SiO2-C18 NPs-based sorbent extraction combined with GC–qMS revealed that the new nanosorbent had a strong ability to retain the target metabolites providing a new, reliable and high throughput strategy for isolation of targeted EVOMs in human urine, suggesting their potential to be applied in other EVOMs.

Establishment of Monstera deliciosa fruit volatile metabolomic profile at different ripening stages using solid-phase microextraction combined with gas chromatography–mass spectrometry

The volatile metabolomic profile of Monstera deliciosa fruits (M. deliciosa, ceriman) at three ripening stages, ripe, half-ripe and unripe, was established using headspace solid-phase microextraction (HS-SPME) combined with gas chromatography–quadrupole mass spectrometry detection (GC–qMS). To obtain the optimal HS-SPME conditions, the main experimental parameters that influence the extraction efficiency and experimental response were analyzed. The highest extraction efficiency was achieved with 1g of ceriman sample, using a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber for 60min at 40°C with 15% NaCl (w/w). After optimization, all ceriman samples were analyzed with the best extraction conditions that allowed to identify 80 volatile metabolites (VOMs), belonging to different chemical groups namely ethyl esters (88.61–77.94%), terpenoids (18.08–9.83%), carbonyl compounds (3.41–1.05%), higher alcohols (1.41–0.51%) and lactones (0.14–0.03%). Thirty-eight of the identified volatile metabolites (47.50%) have not been reported in M. deliciosa, so far, providing a more complete characterization of its volatile composition. The predominant VOMs identified in M. deliciosa fruits were ethyl butanoate, linalool, ethyl hexanoate, ethyl 2-methyl butanoate, butanoic acid, ethyl benzoate and propyl butanoate. Remarkable differences were found in both the quantitative and qualitative composition of M. deliciosa fruits at different ripening stages.Principal component analysis (PCA) provided a suitable tool to differentiate the volatile profile of target fruits among three ripening stages.

Flow-modulation low-pressure comprehensive two-dimensional gas chromatography

The present paper contains research data relative to an approach herein defined as flow-modulation (FM) low-pressure comprehensive two-dimensional gas chromatography, abbreviated as “GC×LP GC”. The abbreviation LP is positioned before the second GC abbreviation because LP conditions were generated across a mega-bore second-dimension column (10m×0.53mm ID), it being connected to a quadrupole mass spectrometer (qMS). Flow modulation was performed with MS-compatible gas flows (7–8mL/min), following recent research work [7]; using such an approach, the main disadvantage of flow modulation, specifically the generation of excessively high second-dimension flows, is avoided. A further noteworthy aspect of the investigation was the use of a long accumulation loop (e.g., 51cm), a modification that greatly improved the general post-modulation peak shape quality. FM GC×LP GC–qMS applications on pure standard compounds, as well as on milk and fish oil fatty acid methyl esters, are shown and discussed.