Static Headspace Gas Chromatography-mass Spectrometry Research Articles

Differentiation of natural indigo and synthetic indigo in dye powders and their dyed products (yarns and fabrics) by static headspace gas chromatography-mass spectrometry

Differentiation of natural indigo and synthetic indigo in dye powders and their dyed products (yarns and fabrics) by static headspace gas chromatography-mass spectrometry

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.”

Effects of temperature and pressure on volatile compounds of black cumin seeds (Nigella sativa L.) oil extracted by supercritical carbon dioxide

AbstractThis study investigated the effects of temperature and pressure on the yield and volatile compound contents of black cumin seed oil (BCO) extracted from black cumin seeds using supercritical carbon dioxide (SCCO2). The solubility of BCO in SCCO2 increased 2.5‐fold as the pressure increased by 10 MPa. Major volatile compounds in BCO were identified using a static headspace gas chromatography–mass spectrometry (SH–GC–MS). Evidence indicated the main volatile components in SCCO2‐extracted BCO to be hexanal, p‐cymene, and thymoquinone. BCO extracted from China‐cultivated black cumin seed contained similar amounts of p‐cymene and thymoquinone. This black cumin seed is classified as the cymene/thymoquinone chemotype and is also found in Indian, Iranian, and Algerian black cumin seeds. Thymoquinone contents in BCO were more sensitive to the extraction temperature than hexanal and p‐cymene contents. The maximum oil yield of 36.28 ± 1.38 wt%, with approximately 2.0 mg of thymoquinone per milliliter of oil, was obtained at extraction temperatures of 50°C and pressures of 30 MPa. A SH–GC–MS could detect small molecules in black cumin seed oil such as hexanal. The results of this work reveal that temperature has more impact on the selectivity of volatile compounds than pressure in supercritical carbon dioxide extraction.

Investigation of benzoic acid and sorbic acid concentrations in tomato paste, pepper paste, ketchup, mayonnaise, and barbeque sauce samples by headspace gas chromatography-mass spectrometry.

In this study, it was aimed at investigating benzoic acid (BA) and sorbic acid (SoA) concentrations in tomato paste, pepper paste, ketchup, mayonnaise, and barbeque sauce samples by a validated static headspace gas chromatography-mass spectrometry (GC-MS) method. Salicylic acid (SalA) was used as internal standard and the measurements were conducted in the wide linear concentration ranges of BA and SoA which were 2.5-5000 and 12.5-5000, respectively. The limit of detections (LODs) were determined to be 1.5 and 4.5 mg/kg while the limit of quantifications (LOQs) were 2.5 and 12.5 mg/kg for BA and SoA, respectively. The average recovery% values of BA and SoA were found to be 98.5% and 98.7% in an open tomato paste sample while these values were 98.7% and 100.3% in a mayonnaise sample, respectively. Accuracy of the proposed method was confirmed by statistically (significance test) evaluating excellent recovery values. In real samples, while the results of the canned tomato pastes and industrial sauce samples were found suitable, BA and SoA ​​were determined in some tomato and pepper paste products sold under the traditional or homemade name although use of the preservatives in the pastes were prohibited. It is vital for public health to prevent adulteration in pastes which is indispensable for Turkish cuisine as well as prevalently consumed in the world. Therefore, the proposed method can be used in food control laboratories due to its reliability and consumption of much less toxic chemical reagents.

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.

Application of Static Headspace GC-MS Method for Selective 1,4-Dioxane Detection in Food Additives.

Efficient detection methods must be developed for 1,4-dioxane due to its suspected status as a human carcinogen, which is highly mobile in food and environmental resources. In this regard, this experiment has been conducted to develop reliable and selective detection and measurement methods by using static headspace (SH) isolation, followed by gas chromatography-mass spectrometry (GC-MS). A new method was developed for determining the spiked 1,4-dioxane contents in a polyethylene glycol 600 (PEG 600). The optimal condition for SH-GC-MS was discussed. The representative ions of 1,4-dioxane and 1,4-dioxane-d8 in the SIM mode of MS are 88 and 96, respectively, and the peaks of the SIM mode were separated and confirmed. The linear range for the method covers 0.25 to 100 mg/L with a coefficient of determination (R2) ≥ 0.999. The method applicability was demonstrated by spike recovery across a variety of food additives (i.e., chlorine bitartrate, choline chloride, polysorbate 20 and 60, and PEG 1000). All spike recovery from the tested samples was in the range of 89.50-102.68% with a precision of 0.44-11.22%. These findings suggest a new analytical method for food safety inspection, and could be applicable for ensuring the safety of foods and environmental and public health on a broad scale.

Static headspace gas chromatography–mass spectrometry for volatile organic compounds in bovine milk samples

AbstractVolatile organic compounds (VOCs) provide insight into the taste and aroma of milk. VOCs in milk are typically analyzed using headspace gas chromatography–mass spectrometry (GC‐MS). While static headspace GC‐MS is a simple and widely applicable analytical technique for the analysis of VOCs in various samples, it has not been frequently applied to milk samples. In this study, static headspace GC‐MS was used to compare the VOCs of three different brands of commercial milk. Three components were identified in the samples, that is, acetone, toluene, and 2‐heptanone, where the concentration ranges of acetone, toluene, and 2‐heptanone in the milk samples were 2.284–3.256, 0.028–0.178, and 0.014–0.020 μg/mL, respectively. A literature review found that all three components were previously reported in milk, while toluene and 2‐heptanone were newly identified using headspace GC‐MS in this study.

Metabolomics approach to identify key volatile aromas in Thai colored rice cultivars.

In addition to white jasmine rice, Thailand has many native-colored rice varieties with numerous health benefits and the potential to become a global economic crop. However, the chemical characteristics of aromatic substances in native-colored rice are still mostly unknown. This study aimed to identify the key volatile aroma compounds and the biosynthetic pathways possibly involved in their formation in Thai native-colored rice varieties, and thus leading to the search for potential genetic markers for breeding colored rice with better aromatic properties. Twenty-three rice varieties in four categories: aromatic white, aromatic black, non-aromatic black, and non-aromatic red, were investigated (n=10 per variety). Seed husks were removed before the analysis of rice volatile aromas by static headspace gas chromatography-mass spectrometry. Untargeted metabolomics approach was used to discover the key volatile compounds in colored rice. Forty-eight compounds were detected. Thirty-eight of the 48 compounds significantly differed among groups at p<0.05, 28 of which at p<0.0001, with the non-aromatic black and red rice containing much lower content of most volatile constituents than the aromatic black and white rice. Focusing on the aromatic black rice, the samples appeared to contain high level of both compound groups of aldehydes (3-methylbutanal, 2-methylbutanal, 2-methylpropanal, pentanal, hexanal) and alcohols (butane-2,3-diol, pentan-1-ol, hexan-1-ol). Biosynthetically, these distinctive black-rice volatile compounds were proposed to be formed from the metabolic degradation of branched-chain amino acids (L-leucine, L-isoleucine and L-valine) and polyunsaturated fatty acids (linoleic acid and α-linolenic acid), involving the branched-chain aminotransferases and keto-acid decarboxylases and the 9-lipoxygonases and 13-lipoxygeases, respectively. The proposed degradative pathways of amino acids and fatty acids were well agreed with the profiles key volatile compounds detected in the Thai native-colored rice varieties.

Optimizing the Distillation of Greek Oregano-Do Process Parameters Affect Bioactive Aroma Constituents and In Vitro Antioxidant Activity?

The aim of the present work was to optimize the conditions of the distillation process at a pilot scale to maximize the yield of specific bioactive compounds of the essential oil of oregano cultivated in Greece, and subsequently to study the in vitro antioxidant activity of these oils. Steam distillation was conducted at an industrial distillery and a Face-Centered Composite (FCC) experimental design was applied by utilizing three distillation factors: time, steam pressure and temperature. Essential oil composition was determined by static headspace gas chromatography-mass spectrometry (HS-GC/MS). To obtain a comprehensive profile of the essential oils, instrumental parameters were optimized, including sample preparation, incubation conditions, sampling process, injection parameters, column thermal gradient and MS conditions. With the applied GC-MS method, more than 20 volatile compounds were identified in the headspace of the oregano essential oils and their relative percentages were recorded. Carvacrol was the most prominent constituent under all distillation conditions applied. Data processing revealed time as the main factor which most affected the yield. The Desired Space (DSc) was determined by conducting a three-dimensional response surface analysis of the independent and dependent variables, choosing yields of thymol and carvacrol as optimization criteria. The in vitro antioxidant activity of the essential oils of all samples was measured in terms of the interaction with the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) after 20 and 60 min. The most prominent essential oils at different distillation conditions were also tested as inhibitors of lipid peroxidation. Higher % values of carvacrol and thymol were correlated to higher antioxidant activity. Evaluating the impact of the distillation conditions on the in vitro results, it seems that lower pressure, less time and higher temperature are crucial for enhanced antioxidant activities.

SHS-GC-MS applied in Coffea arabica and Coffea canephora blend assessment.

Considering the great economic significance of Coffea arabica (arabica) associated with the lower production cost of C. canephora (conilon), blends of these coffees are commercially available to reduce costs and combine sensory attributes. Thus, analytical tools are required to ensure consistency between real and labeled compositions. In this sense, chromatographic methods based on volatile analysis using static headspace-gas chromatography-mass spectrometry (SHS-GC-MS) and Fourier transform infrared (FTIR) spectroscopy associated with chemometric tools were proposed for the identification and quantification of arabica and conilon blends. The peak integration from the total ion chromatogram (TIC) and extracted ion chromatogram (EIC) was compared in multivariate and univariate scenarios. The optimized partial least squares (PLS) models with uninformative variable elimination (UVE) and chromatographic data (TIC and EIC) have similar accuracy according to a randomized test, with prediction errors between 3.3% and 4.7% and Rp2 > 0.98. There was no difference between the univariate models for the TIC and EIC, but the FTIR model presented a lower performance than GC-MS. The multivariate and univariate models based on chromatographic data had similar accuracy. For the classification models, the FTIR, TIC, and EIC data presented accuracies from 96% to 100% and error rates from 0% to 5%. Multivariate and univariate analyses combined with chromatographic and spectroscopic data allow the investigation of coffee blends.

Optimization of a static headspace GC-MS method and its application in metabolic fingerprinting of the leaf volatiles of 42 citrus cultivars.

Citrus leaves, which are a rich source of plant volatiles, have the beneficial attributes of rapid growth, large biomass, and availability throughout the year. Establishing the leaf volatile profiles of different citrus genotypes would make a valuable contribution to citrus species identification and chemotaxonomic studies. In this study, we developed an efficient and convenient static headspace (HS) sampling technique combined with gas chromatography-mass spectrometry (GC-MS) analysis and optimized the extraction conditions (a 15-min incubation at 100 ˚C without the addition of salt). Using a large set of 42 citrus cultivars, we validated the applicability of the optimized HS-GC-MS system in determining leaf volatile profiles. A total of 83 volatile metabolites, including monoterpene hydrocarbons, alcohols, sesquiterpene hydrocarbons, aldehydes, monoterpenoids, esters, and ketones were identified and quantified. Multivariate statistical analysis and hierarchical clustering revealed that mandarin (Citrus reticulata Blanco) and orange (Citrus sinensis L. Osbeck) groups exhibited notably differential volatile profiles, and that the mandarin group cultivars were characterized by the complex volatile profiles, thereby indicating the complex nature and diversity of these mandarin cultivars. We also identified those volatile compounds deemed to be the most useful in discriminating amongst citrus cultivars. This method developed in this study provides a rapid, simple, and reliable approach for the extraction and identification of citrus leaf volatile organic compound, and based on this methodology, we propose a leaf volatile profile-based classification model for citrus.

Examining the mass loss and thermal properties of 3D printed models produced by fused deposition modeling and stereolithography under elevated temperatures

PurposeThis paper aims to study the mass loss of three-dimensional (3D) printed materials at high temperatures. A preconcentration and analysis technique, static headspace gas chromatography-mass spectrometry (SHS-GC-MS), is demonstrated for the analysis of volatile compounds liberated from fused deposition modeling (FDM) and stereolithography (SLA) 3D printed models under elevated temperatures.Design/methodology/approachA total of seven commercial 3D printing materials were tested using the SHS-GC-MS approach. The printed model mass and mass loss were examined as a function of FDM printing parameters including printcore temperature, model size and printing speed, and the use of SLA postprocessing procedures. A high temperature resin was used to demonstrate that thermal degradation products can be identified when the model is incubated under high temperatures.FindingsAt higher printing temperatures and larger model sizes, the initial printed model mass increased and showed more significant mass loss after thermal incubation for FDM models. For models produced by SLA, the implementation of a postprocessing procedure reduced the mass loss at elevated temperatures. All FDM models showed severe structural deformation when exposed to high temperatures, while SLA models remained structurally intact. Mass spectra and chromatographic retention times acquired from the high temperature resin facilitated identification of eight compounds (monomers, crosslinkers and several photoinitiators) liberated from the resin.Originality/valueThe study exploits the high sensitivity of SHS-GC-MS to identify thermal degradation products emitted from 3D printed models under elevated temperatures. The results will aid in choosing appropriate filament/resin materials and printing mechanisms for applications that require elevated temperatures.

Authentication of recycled plastic content in water bottles using volatile fingerprint and chemometrics

The environment is threatened by the continuously increasing volume of plastic residue. Plastic recycling is an interesting alternative to mitigate this problem. However, recycled plastic products may have pollutants from their recycling process, collecting system and/or previous life which may hurt consumers health, thus making it key to authenticate and characterize recycled materials. An innovative non-targeted methodology by means of static headspace gas chromatography-mass spectrometry (SHS-GC-MS) has been developed to measure the volatile organic profile of virgin polyethylene terephthalate (PET) and with diverse content of recycled PET samples. A home-made MS database, with 161 organic compounds characteristics from plastic materials based on the literature, was made. Seventeen of those compounds were found in the studied samples and identified by matching their MS spectra with MS database libraries. These compounds are mainly aldehydes (pentanal, hexanal, heptanal, octanal, nonanal and decanal), and benzene derivatives (styrene, p-xylene, benzaldehyde, methylbenzene, and 1,2-dichlorobenzene) which we found to be the common in the samples of recycled PET. The combination of the dataset consisting in the peak area of the detected species by SHS-GC-MS and the use of chemometrics shown to be a valuable methodology for the discrimination between virgin PET samples and those with different recycled PET content based on their volatile profile. In addition, a novel strategy applying a statistical model based on partial least squares (PLS) regression was proposed, for the first time, to quantify the recycled plastic content in the PET samples.

Chemical ingredients characterization basing on 1H NMR and SHS-GC/MS in twelve cultivars of Coffea arabica roasted beans

This work aimed to study the composition differences of roasted beans between 12 coffee cultivars (Catimor 7963, HIBRIDO DE TIMOR, Ruiru 11, Castillo, DTARI 296, DTARI 366, DTARI 392, DTARI 585, SL28, SL34, Catuai-Amarelo and Catuai-Vermelho) from Bourbon-Typica group and Introgressed group under subtropical humid monsoon climate. The water-soluble compounds of roasted coffee beans were characterized by proton nuclear magnetic resonance spectroscopy (1H NMR), and the aroma components were analyzed by static headspace gas chromatography mass spectrometry (SHS-GC/MS). In total, 20 water soluble compounds and 43 volatile compounds were identified. Both water-soluble and volatile compounds are rich in acidic substances, and the content varied depending on the cultivars. Furthermore, principal component analysis (PCA) clustered 12 coffee cultivars into four groups. The four different chemically defined clusters of Arabica cultivars produced by chemical differences cannot reflect the traditional grouping based on introgressed, and it is one-sided to judge coffee quality based on lineage. These results give further insight into the quality characteristics of different coffee cultivars, which is of great significance for guiding the adjustment of cultivars' structure and the breeding of new cultivars.

The Formation of Methyl Ketones during Lipid Oxidation at Elevated Temperatures.

Lipid oxidation and the resulting volatile organic compounds are the main reasons for a loss of food quality. In addition to typical compounds, such as alkanes, aldehydes and alcohols, methyl ketones like heptan-2-one, are repeatedly described as aroma-active substances in various foods. However, it is not yet clear from which precursors methyl ketones are formed and what influence amino compounds have on the formation mechanism. In this study, the formation of methyl ketones in selected food-relevant fats and oils, as well as in model systems with linoleic acid or pure secondary degradation products (alka-2,4-dienals, alken-2-als, hexanal, and 2-butyloct-2-enal), has been investigated. Elevated temperatures were chosen for simulating processing conditions such as baking, frying, or deep-frying. Up to seven methyl ketones in milk fat, vegetable oils, and selected model systems have been determined using static headspace gas chromatography-mass spectrometry (GC-MS). This study showed that methyl ketones are tertiary lipid oxidation products, as they are derived from secondary degradation products such as deca-2,4-dienal and oct-2-enal. The study further showed that the position of the double bond in the precursor compound determines the chain length of the methyl ketone and that amino compounds promote the formation of methyl ketones to a different degree. These compounds influence the profile of the products formed. As food naturally contains lipids as well as amino compounds, the proposed pathways are relevant for the formation of aroma-active methyl ketones in food.

Development and uncertainty estimation of cryogenic homogenization and static headspace–gas chromatography–mass spectrometry method for the simultaneous determination of twelve toxic volatiles in disposable menstrual products

Volatile organic compounds (VOCs) threaten the health of women who use disposable menstrual products (DMPs). In this study, we aimed to develop a simple and reliable analytical method using a cryogenic mill and static headspace–gas chromatography–mass spectrometry (HS-GC-MS) for the simultaneous determination of twelve toxic VOCs in DMPs, and estimate the measurement uncertainty of the method using the bottom-up approach to ensure the quality of analytical results. Static HS conditions for the direct thermal extraction of the target VOCs from the cryogenically ground sample powders were optimized in terms of extraction temperature and equilibrium time. The separation was achieved using a GC-MS equipped with a VF-624ms column. Cryogenic mill homogenized DMP into powder with 100-μm particles in scanning electron microscopy study. Sample powder was demonstrated to be homogenous as assessed by the homogeneity test. Validation studies showed that the method has reliable performance characteristics: linearity (R2 ≥ 0.9994), limit of quantification (LOQ, 8.4–50.5 ng g−1), precision (relative standard deviation ≤ 18.7%), and accuracy (recovery = 83.4–114.2%) for all the analytes. The proposed method was successfully applied to the commercial products of disposable sanitary pads and tampons. The content of styrene was the highest, followed by those of toluene, hexane, and ethylbenzene. The quantitative data exhibited acceptable precision, as evaluated using the intra-laboratory Horwitz ratio. The expanded uncertainties estimated at three concentration levels ranged from 6.4% to 77.9%. Our simple and reliable method will be useful for quality control testing or quantitative risk assessment and will contribute to resolving the safety issues associated with the risk of human exposure to trace volatile residues in DMPs.

Contribution of aroma compounds to the antioxidant properties of roasted white yam (Dioscorea rotundata)

BackgroundThe aroma chemistry and the contribution of the aroma compounds to the anti-oxidative properties of roasted yam have yet to be characterized. The growing popularity of roasted yam in regions where they are being consumed calls for a concerted effort to elucidate their aroma chemistry as well as their anti-oxidative properties.ResultsThe aroma compounds in roasted white yam (Dioscorea rotundata) were isolated and identified using static headspace-gas chromatography-mass spectrometry (SH–GC–MS) and gas chromatography–olfactometry (GC–O). In addition, the anti-oxidative activities of the most abundant volatile heterocyclic compounds (2 pyrroles, 4 furans and 3 pyrazines) were evaluated on their inhibitory effect towards the oxidation of hexanal for a period of 30 days. Twenty-nine aroma-active compounds with a flavour dilution (FD) factor range of 2–256 and an array of odour notes were obtained. Among them, the highest odour activities (FD ≥ 128) factors were determined for 2-acetyl furan and 2-acetylpyrrole. Other compounds with significant FD factors ≥ 32 were; 2-methylpyrazine, ethyl furfural, and 5-hydroxy methyl furfural.ConclusionResults of the anti-oxidative activity showed that the pyrroles exhibited the greatest antioxidant activity among all the tested heterocyclic compounds. This was followed by the furans and the pyrazines which had the least antioxidant activity.

Spatio-vertical characterization of the BTEXS group of VOCs in Chinese agricultural soils

Ubiquitous contamination of the BTEXS (benzene, toluene, ethylbenzene, xylene, and styrene) group in soils is a significant concern for ecological safety. However, comprehensive spatio-vertical survey of the BTEXS group on a national scale is rare to date. Using a static headspace gas chromatography–mass spectrometry method (HS-GCMS), this study performed a quantitative analysis of BTEXS levels in soils from Chinese rural areas in 2013 and 2016. The median ∑BTEXS concentrations in surface soils in 2013 and 2016 were 37.5 and 34.4 ng g−1 dry weight, respectively. Toluene was the dominant pollutant, accounting for approximately 41.6% and 32.1% of the total levels. BTEXS contamination was higher in Shanxi province, Northeast China, and Yunnan-Guizhou Plateau compared to the other regions. Vertically, toluene, m,p′-xylene and o′-xylene concentrations were significantly higher in the top soil layer (0–15 cm) and decreased significantly with increasing soil depth (p < 0.05). Higher soil organic matter was significantly associated with higher BTEXS concentrations of sampling site. BTEXS was also enhanced at sites with higher elevations and lower temperature due to global distillation effects. The findings of this study could help decision-makers to protect against BTEXS contamination in rural areas. These findings provide a basis for further study of the mechanism of BTEXS migration and transport in large-scale environment. CapsuleSpatio-vertical distribution, influence factors, exposure risks of BTEXS in soils from Chinese agricultural region was studied.

Headspace Gas Chromatography-Mass Spectrometry for Volatile Components Analysis in Ipomoea Cairica (L.) Sweet Leaves: Natural Deep Eutectic Solvents as Green Extraction and Dilution Matrix.

In this study, natural deep eutectic solvents (NADESs) were used as both the extraction and dilution matrix in static headspace gas chromatography-mass spectrometry (SHS-GC-MS) for the analysis of volatile components in Ipomoea cairica (L). Sweet (ICS) leaves. Six NADESs were prepared and the NADESs composed of choline chloride and glucose with a 1:1 molar ratio containing 15% water were preferred due to the better peak responses. A total of 77 volatiles in ICS leaves were detected and tentatively identified by mass spectral matching with the US National Institute of Standards and Technology (NIST, 2014) Mass Spectral Library and the retention index-assisted qualitative method. These 77 volatile components were mainly terpenoids, aromatics, and aliphatics. Among them, β-elemene, β-caryophyllene, α-humulene, and 2, 4-di-tert-butylphenol were found to be the main components. This investigation verified that the use of NADESs is an efficient green extraction and dilution matrix of the SHS-GC-MS method for direct volatile component analysis of plant materials without extra extraction work.

Volatiles of Thymus serpyllum Obtained by Three Different Methods

Volatiles of Thymus serpyllum L. were obtained by hydrodistillation (HD), simultaneous hydrodistillation, and extraction (SDE) and static headspace gas chromatography-mass spectrometry analysis (head space [HS]), respectively. Monoterpenes were the most dominant in all 3 techniques (84.8%-94.2%). Essential oil profiles obtained by HD and SDE were similar, with oxygenated monoterpenes being the most abundant (up to 75.4%). In HS volatiles of T. serpyllum monoterpene hydrocarbons strongly dominated (94.2%). The main compounds were α-terpinyl acetate (HD and SDE) and myrcene (HS).