Headspace GC-MS Research Articles

Comparison of volatile constituents in two types of mugwort leaves (produced in Qichun and Nanyang) using the headspace GC-MS

Objective To compare the volatile constituents in mugwort leaves produced in Qichun, Hubei Province and Nanyang, Henan Province.

Effect of the two drying approaches on the volatile profiles of button mushroom (Agaricus bisporus) by headspace GC–MS and electronic nose

Button mushroom slices were dehydrated using freeze drying (FD) or combined with microwave vacuum drying (FMVD), and the changes in volatile composition were investigated and compared by using headspace GC–MS and electronic nose (E-nose). The results showed that the content of C8 compounds decreased during FD/FMVD process, while more alkanes and heterocyclic compounds were generated in the latter drying periods. The content of original thermal volatile compounds in FMVD products were significantly lower compared to FD, and the same trent was observed on alkanes and heterocyclic compounds. Moreover, the volatile compounds of FMVD products were more similar with fresh ones according to cluster analysis, and the critical point of change of volatile compounds might be at the end of sublimation period. In addition, E-nose could clearly discriminate button mushroom samples subject to different drying periods, the result obtained by E-nose showed good identity compared with GC–MS.

Comparative Chemical Analysis ofMentha piperitaandM. spicataand a Fast Assessment of Commercial Peppermint Teas

The hydrodistilled essential oils and volatile compounds (by static headspaces technique) of Mentha piperita L. and M spicata L. were characterized by GC-MS. Headspace analysis of Mentha piperita revealed the existence of menthone (25.4%), 1,8-cineole (17.7%) and menthol (12.1%) as the main components, while the essential oil contained high amounts of menthol (46.8%) and menthone (25.6%). By contrast, headspace analysis of M. spicata showed a high content of limonene (37.0%) together with carvone (13.0%), β-pinene (10.4%) and α-pinene (9.8%), while the essential oil was reach in carvone (51.7%), dihydrocarveol (11.5%) and cis-dihydrocarvone (9.1%). Eleven samples of peppermint tea available on the Romanian market were analysed by headspace GC-MS. The volatile profile of the tea samples was compared with that of Mentha piperita L. and certain differences were emphasized and discussed.

Approaches to the determination of C60 and C70 fullerene and their mixtures in aqueous and organic solutions

The solvent-exchange process from toluene was used for preparing aqueous dispersions of C60 and C70 without preconcentration with final concentrations of 180 ± 2 and 62 ± 1 μM, respectively, which exceeds the previously reported maximum concentrations for C60 more than 6-fold; for C70 such an aqueous dispersion is prepared for the first time. The residual quantity of the organic solvent and low-molecular compounds determined by headspace GC-MS was not more than 1 ppb. The procedure for the determination of fullerenes in aqueous dispersions is developed using a total organic carbon analyzer and absorption spectra; LOD, 50 nM, LOQ, 200 nM by TOC. Spectrophotometric determination of fullerenes in their aqueous dispersions was optimized: for C60 at 268 nm: LOD, 0.1 μM, LOQ, 0.3 μM, for C70 at 218 nm: LOD, 0.1 μM, LOQ, 0.3 μM. RSD mixture quantification by Vierordt’s method in the range of 2 – 20 μM does not exceed 0.14 for C60 and 0.09 C70. RSD for toluene fullerene mixtures by Vierordt’s method in the range of 2 – 20 μM does not exceed 0.10 for C60 and 0.06 for C70.

Human metabolism of α-pinene and metabolite kinetics after oral administration.

We studied the human in vivo metabolism and the elimination kinetics of α-pinene (αPN), a natural monoterpene which commonly occurs in the environment. Four volunteers were exposed to a single oral dose of 10mg αPN. Each subject provided one pre-exposure and subsequently all post-exposure urine samples up to 24h after administration. Additionally, blood samples were drawn hourly from two volunteers for 5h. The analysis of the parent compound in blood was performed by a headspace GC-MS procedure, whereas the proposed αPN metabolites myrtenol (MYR) and cis- and trans-verbenol (cVER; tVER) were quantified in blood and urine using GC-PCI-MS/MS. Unknown metabolites were investigated using GC-PCI-MS full-scan analyses. The urinary concentration of the metabolites reached their maxima 1.6h after exposure. Afterwards, they declined to the pre-exposure levels within the 24-h observation period with elimination half-lives of 1.5h (MYR) and 1.6h (cVER and tVER). The total eliminated amounts corresponded to 1.5% (MYR), 5.6% (cVER), and 4.1% (tVER) of the orally applied dose. The GC-PCI-MS full-scan analyses identified three novel metabolites, of which one conforms to myrtenic acid (MYRA). A re-analysis of MYRA in urine showed maximum elimination 1.6h after αPN ingestion, an elimination half-life of 1.4h, and a share of the oral dose of 6.7%. The study revealed that the human in vivo metabolism of αPN proceeds fast and elimination of metabolites takes places rapidly. The metabolism of αPN is dominated by extensive oxidation reactions at the methyl side-chains yielding in carboxylic acid structures as well as by allylic oxidation of the cyclohexenyl backbone, whereas predicted products of a double-bond oxidation were not detected.

Development of a dynamic headspace gas chromatography–mass spectrometry method for on-site analysis of sulfur mustard degradation products in sediments

Sampling teams performing work at sea in areas where chemical munitions may have been dumped require rapid and reliable analytical methods for verifying sulfur mustard leakage from suspected objects. Here we present such an on-site analysis method based on dynamic headspace GC–MS for analysis of five cyclic sulfur mustard degradation products that have previously been detected in sediments from chemical weapon dumping sites: 1,4-oxathiane, 1,3-dithiolane, 1,4-dithiane, 1,4,5-oxadithiephane, and 1,2,5-trithiephane. An experimental design involving authentic Baltic Sea sediments spiked with the target analytes was used to develop an optimized protocol for sample preparation, headspace extraction and analysis that afforded recoveries of up to 60–90%. The optimized method needs no organic solvents, uses only two grams of sediment on a dry weight basis and involves a unique sample presentation whereby sediment is spread uniformly as a thin layer inside the walls of a glass headspace vial. The method showed good linearity for analyte concentrations of 5–200ng/g dw, good repeatability, and acceptable carry-over. The method's limits of detection for spiked sediment samples ranged from 2.5 to 11μg/kg dw, with matrix interference being the main limiting factor. The instrumental detection limits were one to two orders of magnitude lower. Full-scan GC–MS analysis enabled the use of automated mass spectral deconvolution for rapid identification of target analytes. Using this approach, analytes could be identified in spiked sediment samples at concentrations down to 13–65μg/kg dw. On-site validation experiments conducted aboard the research vessel R/V Oceania demonstrated the method's practical applicability, enabling the successful identification of four cyclic sulfur mustard degradation products at concentrations of 15–308μg/kg in sediments immediately after being collected near a wreck at the Bornholm Deep dumpsite in the Baltic Sea.

Volatile Fraction of Fool's Watercress (Apium nodiflorum) as a New Spice Herb and Ingredient for Salads

This work displays the preliminary results of a study of the volatile fraction of fool´s watercress (FW) ( Apium nodiflorum ), an underutilized vegetable species with potential use for salads and as spice. A comparative study of the volatile fraction of FW samples from Northern Valencia periurban area and samples from relatives parsley and celery was performed by head-space solid phase microextraction (HS/SPME) and GC-MS analysis. The profile of FW was richer than the profile of celery and parsley and resulted as a mixture of those ones. Moreover, some volatiles like isothiocyanates were identified as specific of FW. Thus, this species can be considered similar to its relatives but more intense and consequently, may be used in salads or even as spice herb.

Analysis of the reaction products from micro-vial pyrolysis of the mixture glucose/proline and of a tobacco leaf extract: Search for Amadori intermediates

Micro-vial pyrolysis (PyroVial) was used to study the production of compounds important for the aroma of heat-treated natural products such as tobacco. Firstly, a mixture of glucose and proline was pyrolyzed as model, as this sugar and amino acid are also abundant in tobacco leaf (Nicotiana tobacum L.). The pyrolysate was analyzed using headspace-GC–MS, liquid injection GC–MS and LC–MS. Next, micro-vial pyrolysis in combination with LC–MS was applied to tobacco leaf extract. Using MS deconvolution, molecular feature extraction and differential analysis it was possible to identify Amadori intermediates of the Maillard reaction in the tobacco leaf extract. The intermediate disappeared as was the case for 1-deoxy-1-prolino-β-d-fructose or the concentration decreased in the pyrolysate compared to the original extract such as for the 1-deoxy-1-[2-(3-pyridyl)-1-pyrrolidinyl]-β-d-fructose isomers indicating that Amadori intermediates are important precursors for aroma compound formation.

Analysis of flavor volatiles of some Iranian rice cultivars by optimized static headspace gas chromatography–mass spectrometry

Static headspace coupled to gas chromatography–mass spectrometry (SHS-GC–MS) was applied to the extraction and analysis of volatiles in some Iranian rice varieties. Optimization of static headspace sampling was investigated by full factorial design and a face-centered central composite design procedure. According to the results of full factorial design, the effective parameters of static headspace sampling were extraction temperature (T) and extraction time (t). Then a central composite design was applied to find the optimum level of these factors. The results of three replications of experiments under optimal conditions (T = 100 °C, t = 900 s) indicated that, there is a good agreement between the predicted (5.28) and experimental (5.20) responses (98.48 %). Then developed method was used for analysis of volatile chemicals in three Iranian rice cultivars. According to the results of GC–MS analysis 26, 21, and 19 chemicals were assigned to Domsiah, Deylamani, and Tarom rice samples, respectively. The major compounds identified in these samples were the alkyl aldehydes. The results obtained are promising for future isolation and identification of the flavor volatiles of other rice cultivars by SHS-GC–MS analysis. The method of static headspace GC–MS has been developed and has proven to provide an effective means for simple and rapid quantitative analysis of the aroma compound of rice. A central composite design was applied to found the optimal conditions. The results of three replications of experiments under optimal conditions (T = 100 °C, t = 900 s) indicated that, there is a good agreement between the predicted (5.28) and experimental (5.20) responses (98.48 %). Then, developed method was used to analyze the volatile chemicals in the rice samples. A total of 26, 21, and 19 chemicals were assigned to Domsiah, Deylamani, and Tarom rice samples, respectively.

Analysis of Volatile Compounds by Headspace GC-MS and Amino acid of Allium hookeri

Analysis of Volatile Compounds by Headspace GC-MS and Amino acid of Allium hookeri

Corolla structure and fragrance components in Styrax tonkinensis

The structure of petals and volatile compounds from fresh Styrax tonkinensis cut flowers were investigated by using micro-techniques and a headspace solid-phase micro-extraction technique coupled with GC–MS. Styrax tonkinensis is a fast-growing woody plant that is used for timber and as a medicinal plant. In the present study, the structures of the flower petals of S. tonkinensis were investigated and volatile compounds emitted from the petals were identified. Light microscopy, scanning and transmission electron microscopy were used to describe petal structure. The volatile constituents were analyzed using a headspace GC–MS technique. Results indicated that glandular hairs and 8–9 layers of parenchyma cells in the cream-white petals play a key role in emitting the fragrance. An analysis of the volatile components emitted by the cut flowers of S. tonkinensis at two stages of flower development (prior to and at anthesis) indicated that monoterpenes, such as 1,3,6-octatriene, 3,7-dimethyl-(Z), and α-pinene, were the most abundant volatile components in all samples.

Composition of Trans-anethol and Other Aromatic Volatiles in Anisated Alcoholic Beverages by Head-Space GC-MS Chromatography

Composition of Trans-anethol and Other Aromatic Volatiles in Anisated Alcoholic Beverages by Head-Space GC-MS Chromatography

Chemical changes of thermally sterilized broccoli puree during shelf-life: Investigation of the volatile fraction by fingerprinting-kinetics

For the first time in literature, this study evaluates the potential of a “fingerprinting-kinetics” strategy to investigate how the volatile fraction of thermally sterilized broccoli puree is affected by shelf-life. Samples were stored at four storage temperatures (20 °C, 28 °C, 35 °C and 42 °C). The volatile fraction was analyzed using headspace GC-MS fingerprinting as a function of time and temperature (kinetics). Fingerprinting enabled selection of sulfur-containing compounds (dimethyl sulfide, carbon disulfide, dimethyl pentasulfide, dimethyl trisulfide, bis-(methylthio)-phosphine and methyl (methylthio)methyl disulfide), nitriles (heptanonitrile, 5-methyl-hexanenitrile, hexanenitrile and 5-(methylthio)-pentanenitrile), fatty acid derivatives (octanal and 2-ethyl-1-hexanol), furanic compounds (2-ethylfuran) and Strecker aldehydes (3-methylbutanal) as volatiles significantly changing during shelf-life. In general, most of the volatiles decreased as a function of shelf-life. Next, the suitability of the volatiles (selected by fingerprinting) as markers for accelerated shelf-life testing was investigated. Based on the applied kinetic modelling, 3-methylbutanal was identified as a potential marker.

Penarines A–F, (nor-)sesquiterpene carboxylic acids from Hygrophorus penarius (Basidiomycetes)

Five sesquiterpene carboxylic acids (1–5) and one nor-sesquiterpene carboxylic acid (6) of the very rare ventricosane type, named penarines A–F, were isolated from fruiting bodies of the basidiomycete Hygrophorus penarius (Hygrophoraceae). This is the first report of (nor)-sesquiterpenes isolated from basidiocarps of the family Hygrophoraceae. Their structures were elucidated on the basis of extensive 1D (1H, 13C) and 2D (HSQC, HMBC, COSY, ROESY) NMR spectroscopic analyses as well as high-resolution mass spectrometry studies. Additionally, the only known member of this rare type of sesquiterpenes, ventricos-7(13)-ene (7), could be identified via headspace GC–MS analysis in a fruiting body of H. penarius. Compounds 1–6 were devoid of remarkable antifungal activity against Cladosporium cucumerinum. Additionally, the cytotoxic activities of compounds 1 and 2 were evaluated against the human prostate cancer cell line PC-3 and the colon cancer cell line HT-29 showing no significant cytotoxic activity.

HS–GC–MS method for the analysis of fragrance allergens in complex cosmetic matrices

Potential allergenic fragrances are part of the Cosmetic Regulation with labelling and concentration restrictions. This means that they have to be declared on the ingredients list, when their concentration exceeds the labelling limit of 10ppm or 100ppm for leave-on or rinse-off cosmetics, respectively. Labelling is important regarding consumer safety. In this way, sensitised people towards fragrances might select their products based on the ingredients list to prevent elicitation of an allergic reaction. It is therefore important to quantify potential allergenic ingredients in cosmetic products.An easy to perform liquid extraction was developed, combined with a new headspace GC–MS method. The latter was capable of analysing 24 volatile allergenic fragrances in complex cosmetic formulations, such as hydrophilic (O/W) and lipophilic (W/O) creams, lotions and gels. This method was successfully validated using the total error approach. The trueness deviations for all components were smaller than 8%, and the expectation tolerance limits did not exceed the acceptance limits of ±20% at the labelling limit.The current methodology was used to analyse 18 cosmetic samples that were already identified as being illegal on the EU market for containing forbidden skin whitening substances. Our results showed that these cosmetic products also contained undeclared fragrances above the limit value for labelling, which imposes an additional health risk for the consumer.

Comprehensive metabolomics to evaluate the impact of industrial processing on the phytochemical composition of vegetable purees

The effects of conventional industrial processing steps on global phytochemical composition of broccoli, tomato and carrot purees were investigated by using a range of complementary targeted and untargeted metabolomics approaches including LC–PDA for vitamins, 1H NMR for polar metabolites, accurate mass LC–QTOF MS for semi-polar metabolites, LC–MRM for oxylipins, and headspace GC–MS for volatile compounds. An initial exploratory experiment indicated that the order of blending and thermal treatments had the highest impact on the phytochemicals in the purees. This blending-heating order effect was investigated in more depth by performing alternate blending-heating sequences in triplicate on the same batches of broccoli, tomato and carrot. For each vegetable and particularly in broccoli, a large proportion of the metabolites detected in the purees was significantly influenced by the blending-heating order, amongst which were potential health-related phytochemicals and flavour compounds like vitamins C and E, carotenoids, flavonoids, glucosinolates and oxylipins. Our metabolomics data indicates that during processing the activity of a series of endogenous plant enzymes, such as lipoxygenases, peroxidases and glycosidases, including myrosinase in broccoli, is key to the final metabolite composition and related quality of the purees.

Chemical hazards present in liquids and vapors of electronic cigarettes.

Electronic (e-)cigarettes have emerged in recent years as putative alternative to conventional tobacco cigarettes. These products do not contain typical carcinogens that are present in tobacco smoke, due to the lack of combustion. However, besides nicotine, hazards can also arise from other constituents of liquids, such as solvents, flavors, additives and contaminants. In this study, we have analyzed 28 liquids of seven manufacturers purchased in Germany. We confirm the presence of a wide range of flavors to enhance palatability. Although glycerol and propylene glycol were detected in all samples, these solvents had been replaced by ethylene glycol as dominant compound in five products. Ethylene glycol is associated with markedly enhanced toxicological hazards when compared to conventionally used glycerol and propylene glycol. Additional additives, such as coumarin and acetamide, that raise concerns for human health were detected in certain samples. Ten out of 28 products had been declared "free-of-nicotine" by the manufacturer. Among these ten, seven liquids were identified containing nicotine in the range of 0.1-15 µg/ml. This suggests that "carry over" of ingredients may occur during the production of cartridges. We have further analyzed the formation of carbonylic compounds in one widely distributed nicotine-free brand. Significant amounts of formaldehyde, acetaldehyde and propionaldehyde were only found at 150 °C by headspace GC-MS analysis. In addition, an enhanced formation of aldehydes was found in defined puff fractions, using an adopted machine smoking protocol. However, this effect was delayed and only observed during the last third of the smoking procedure. In the emissions of these fractions, which represent up to 40 % of total vapor volume, similar levels of formaldehyde were detected when compared to conventional tobacco cigarettes. By contrast, carbonylic compounds were hardly detectable in earlier collected fractions. Our data demonstrate the necessity of standardized machine smoking protocols to reliably address putative risks of e-cigarettes for consumers.

Release and antibacterial activity of allyl isothiocyanate/β-cyclodextrin complex encapsulated in electrospun nanofibers

Allyl isothiocyanate (AITC) is known as an efficient antibacterial agent but it has a very high volatility. Herein, AITC and AITC/β-cyclodextrin (CD)-inclusion complex (IC) incorporated in polyvinyl alcohol (PVA) nanofibers were produced via electrospinning. SEM images elucidated that incorporation of AITC and AITC/β-CD-IC into polymer matrix did not affect the bead-free fiber morphology of PVA nanofibers. 1H-NMR and headspace GC-MS analyses revealed that very low amount of AITC was remained in PVA/AITC-NF because of the rapid evaporation of AITC during the electrospinning process. Nevertheless, much higher amount of AITC was preserved in the PVA/AITC/β-CD-IC-NF due to the CD inclusion complexation. The sustained release of AITC from nanofibers was evaluated at 30°C, 50°C and 75°C via headspace GC–MS. When compared to PVA/AITC-NF, PVA/AITC/β-CD-IC-NF has shown higher antibacterial activity against Escherichia coli and Staphylococcus aureus due to the presence of higher amount of AITC in this sample which was preserved by CD-IC.

High-precision quadruple isotope dilution method for simultaneous determination of nitrite and nitrate in seawater by GCMS after derivatization with triethyloxonium tetrafluoroborate

Quadruple isotope dilution mass spectrometry (ID4MS) has been applied for simultaneous determination of nitrite and nitrate in seawater. ID4MS allows high-precision measurements and entails the use of isotopic internal standards (18O-nitrite and 15N-nitrate). We include a tutorial on ID4MS outlining optimal experimental design which generates results with low uncertainties and obviates the need for direct (separate) evaluation of the procedural blank. Nitrite and nitrate detection was achieved using a headspace GCMS procedure based on single-step aqueous derivatization with triethyloxonium tetrafluoroborate at room temperature. In this paper the sample preparation was revised and fundamental aspects of this chemistry are presented. The proposed method has detection limits in the low parts-per-billion for both analytes, is reliable, precise, and has been validated using a seawater certified reference material (MOOS-2). Simplicity of the experimental design, low detection limits, and the use of quadruple isotope dilution makes the present method superior to the state-of-the-art for determination of nitrite and nitrate, and an ideal candidate for reference measurements of these analytes in seawater.

Chemometric analysis of volatiles of propolis from different regions using static headspace GC-MS

Abstract Six samples of propolis were analyzed in the paper: a sample from Brazil, Estonia, China and three samples from different locations of Uruguay. Static headspace technique coupled with gas chromatography-mass spectrometry analysis has been applied for the determination of the characteristic volatile profile with the aim to differentiate the propolis from different regions. Monoterpenes (α- and β-pinenes) were predominant in all samples, except the sample from China. This sample separated itself by the alcohols 3-methyl-3-buten-1-ol and 3-methyl-2-buten-1-ol, (40.33% and 11.57%, respectively) and ester 4-penten-1-yl acetate (9.04%). α-Pinene and β-pinene composed 64.59–77.56% of volatiles in Brazilian and Uruguayan propolis, and 29.43% in Estonian propolis. Brazilian propolis was distinguished by a high amount of β-methyl crotonaldehyde (10.11%), one of Uruguayan samples 3- by limonene (15.58%), and the Estonian sample — by eucalyptol (25.95%). Statistical investigation of the samples was made applying principal component, hierarchical cluster and K-Means cluster analyses. Various data pre-processing techniques were proposed and used to study and obtain the important volatile compounds contributed to the differentiation of the propolis samples from different regions to separate clusters.