Effects of Broth pH and Chilling Storage on the Changes in Volatile Profiles of Boiled Chicken Flesh.

This study investigated the changes in volatile compounds in chicken flesh after boiling at various pHs (6.0-9.0) and after chilling storage (4.0±1.0°C) for 7 d. The volatile compounds were assessed qualitatively and quantitatively by using a headspace gas chromatography-mass spectrometry analysis. Twenty-one volatile compounds were discovered and categorized as amine, aldehyde, alcohol, ketone, acid, and furan. One type of amine, (2-aziridinylethyl) amine, was the most prevalent volatile component, followed by aldehyde, ketone, aldehyde, acid, ester, and furan. The results showed that the quantity and quality of the volatile compounds were influenced by a pH of the boiling medium. Additionally, the types and volatile profiles of the chicken were altered during chilling. In particular, in the chicken that was boiled at a pH of 8.0, the hexanal (an aldehyde) content increased the most after 7 d of chilling. Moreover, various alcohols formed after the 7 d of chilling of the chicken that was boiled at pHs of 8.0 and 9.0. Because of the oxidation and degradation of fat and proteins, the most altering volatile compounds were the reducing amines and the increasing aldehydes.

Innovative insights into the roasting-driven transformation of volatile compounds and quality markers in flaxseed (Linum usitatissimum L.) oil.

Roasting is essential for developing the characteristic aroma of flaxseed oil (FSO), yet its impact on oil quality remains underexplored. This study employed headspace-gas chromatography-mass spectrometry coupled with multivariate analysis to elucidate the dynamic changes in volatile compounds and quality characteristics of FSO subjected to varying roasting temperatures. Our findings revealed that seven key aroma compounds, identified through the variable importance in the projection scores of partial least square-discrimination analysis models and relative aroma activity value, served as molecular markers indicative of distinct roasting temperatures. These compounds included 2,5-dimethylpyrazine, 2-pentylfuran, (E)-2-pentenal, 2-ethyl-3,6-dimethylpyrazine, heptanal, octanal, and 2-hexenal. Notably, roasting at 200°C was found to enhance oil stability and antioxidant capacity, with phenolic compounds and Maillard reaction products playing synergistic roles in bolstering these qualities. Network analysis further uncovered significant correlations between these key aroma compounds and quality characteristics, offering novel perspectives for assessing FSO quality under diverse roasting conditions. This research not only enriched our understanding of the roasting process's impact on FSO but also provided valuable guidance for the optimization of industrial roasting practices. This study would provide important practical applications in aroma regulation and process optimization of flaxseed oil. .

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.

Identification of floral aroma components and molecular regulation mechanism of floral aroma formation in Phalaenopsis.

BACKGROUND: Most Phalaenopsis cultivars have almost no aroma, with a few exceptions. Phalaenopsis presents significant challenges in fragrance breeding due to its weak aroma and low fertility. It is therefore necessary to identify the aroma components and key regulatory genes in Phalaenopsis cultivars like 'Orange Beauty', 'Brother Sara Gold', 'Purple Martin', 'H026', 'SK16', 'SX098', and 'SH51', to improve the aroma of the common Phalaenopsis. RESULTS: Floral aroma components were tested on nine Phalaenopsis species, using smell identification and headspace gas chromatography-mass spectrometry. The result showed that alcohols, esters, and alkenes were the key specific components in the different species and cultivar aromas and the aroma intensity and component content of cultivars with different colors were different. The main components of the floral aromas in Phalaenopsis were alcohols (including eucalyptol, linalool, citronellol, and 1-hexanol), esters (including hexyl acetate, leaf acetate, and dibutyl phthalate), alkenes (including pinene and sabinene) and arenes (like fluorene). The transcriptome of flowers in the bud stage and bloom stage of P. 'SH51' was sequenced and 5999 differentially expressed genes were obtained. The contributions of the phenylpropionic acid/phenyl ring compound and the terpene compound to the aroma were greater. Sixteen genes related to phalaenopsis aroma were found. TC4M, PAL, CAD6, and HR were related to phenylpropanoid synthesis pathway. SLS, TS10, and P450 were related to the synthesis pathway of terpenes. TS10 and YUCCA 10 were involved in tryptophan metabolism. CONCLUSION: This is the first report on the floral aroma components and regulatory genes in Phalaenopsis. The proposed method and research data can provide technical support for Phalaenopsis breeding. © 2024 Society of Chemical Industry.

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

BACKGROUND: Exhaled 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. METHODS: A549 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. RESULTS: Following 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. CONCLUSIONS: Hyperoxia 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.

Identification of geographical origins of soybean pastes using headspace gas chromatography-mass spectrometry by selecting sample-descriptive components with an Incremental Association Markov Blanket.

The identification of geographical origins of soybean pastes using headspace gas chromatography-mass spectrometry was attempted in this study. Since soybean paste was odor-rich, 36 components were identified in the imported and domestic soybean samples. t-Test, variable importance in projection (VIP), and Incremental Association Markov Blanket (IAMB) were employed to select proper components that could effectively discriminate the two sample groups. The discrimination accuracies were below 87.3 % when all 36 components were fed for either LDA, k-NN, or SVM. When the five t-test-selected components or six VIP score-selected components were employed, the accuracies improved to 95.2-96.2 %. The IAMB selected three different components were 3-methylbutanal, 4-methylnonane, and 2,3-pentanedione, and the correlations among their peak areas were not significant. This suggests that these three components were independently relevant for the discrimination. The accuracy obtained using these three components was superior, 97.7 %, as undescriptive and/or redundant components for the discrimination were excluded.

Analysis and risk assessment of vinyl chloride emitted from aerosol products.

The objectives of this study were to develop a novel analytical method for quantifying vinyl chloride (VC) emitted from aerosol products, to provide analytical data on VC in aerosol products, and to evaluate consumer VC exposure by aerosol products. Our quantitative method involves absorbing VC into dimethyl sulfoxide and analyzing it using headspace gas chromatography/mass spectrometry. The correlation coefficients of the VC calibration curves were ≥ 0.9994 in the range of 0.16-80 µg/mL VC standard gases, which were prepared under either nitrogen or emission gases containing dimethyl ether or liquid petroleum gas. VC concentrations in these emission gases were calculated using a VC calibration curve from standard gases prepared under nitrogen; they were within ± 10% of the actual concentrations. We analyzed 39 household aerosol products; VC concentrations of 0.095, 0.098, and 0.28 µg/L were detected in three polyvinyl chloride spray paints. Consumer VC inhalation exposure level was estimated through an exposure scenario, and the hazard quotient was confirmed to be very low when comparing the exposure level with a cancer risk level of 10-5 for inhaled VC. These results suggest that the human health risk from VC in spray paint was low.

An Evaluation Model for the Quality of Frying Oil Using Key Aldehyde Detected by HS-GC/MS.

To establish a practical model for evaluating the oxidation of frying oil using aldehydes, the aldehydes of 10 commercial oils during frying at 180 °C were identified using headspace-gas chromatography/mass spectrometry, and the changes of common aldehydes and their correlation with carbonyl values (CV) were analyzed. The results showed that the total peak area of aldehydes increased significantly with heating time, which was related to the fatty acid and tocopherol contents of the oils. There were four common aldehydes with different trends during frying, namely, pentanal, hexanal, (E)-hept-2-enal, and nonanal. Moreover, pentanal with a high correlation with CV was selected as the quality evaluating index of frying oil due to its stable accumulation over time. Based on the linear fitting relationships between CV and pentanal, as well as the initial content ratio of linoleic acid to palmitic acid and total tocopherols in oils, a predictive model was established for evaluating the quality of frying oils with high precision and non-reagent by using mass spectrometry. In summary, this work provides theoretical support for using aldehyde as the quality evaluation index of frying oil and provides a new idea for evaluating oil deterioration from the perspective of volatile compounds.

Effects of Drying Methods on the Volatile Compounds of Alliummongolicum Regel.

Allium mongolicum Regel (AMR) is a traditional Mongolian food. Various drying methods play an important role in foodstuff flavor. However, the effect of different drying methods on AMR is limited. In this study, freeze drying (FD), vacuum drying (VD), and hot-air drying (HAD) were applied to dry fresh AMR to a moisture content of 8% (wet basis); headspace gas chromatography mass spectrometry was adopted to identify volatile compounds in AMR; and principal component analysis and fingerprint similarity analysis based on the Euclidean distance was used to distinguish the fresh and three dried treatments. In total, 113 peaks were detected and 102 volatile compounds were identified. Drying causes significant changes to the amounts of volatile compounds in AMR, and the drying method plays a key role in determining which volatile compounds appear. Compared to FD, VD and HAD were more appropriate for drying AMR because the volatile compounds after VD and HAD were closer to those of fresh AMR. These findings can provide a scientific basis to help to preserve future seasonal functional food and aid in Mongolian medicine production.

[High-speed identification of odor changes and substance basis of Myristicae Semen mildew by electronic nose and HS-GC-MS].

This study adopted headspace-gas chromatography-mass spectrometry(HS-GC-MS) and electronic nose to detect volatile components from Myristicae Semen samples with varying degrees of mildew, aiming at rapidly identifying odor changes and substance basis of Myristicae Semen mildew. The experimental data were analyzed by electronic nose and principal component analysis(PCA). The results showed that Myristicae Semen samples were divided into the following three categories by electronic nose and PCA: mildew-free samples, slightly mildewy samples, and mildewy samples. Myristicae Semen samples with different degrees of mildew greatly varied in volatile components. The volatile components in the samples were qualitatively and quantitatively detected by HS-GC-MS, and 59 compounds were obtained. There were significant differences in the composition and content in Myristicae Semen samples with different degrees of mildew. The PCA results were the same as those by electronic nose. Among them, 3-crene, D-limonene, and other terpenes were important indicators for the identification of mildew. Bicyclo[3.1.0]hexane, 4-methylene-1-(1-methylethyl)-, terpinen-4-ol, and other alcohols were key substances to distinguish the degree of mildew. In the later stage of mildew, Myristicae Semen produced a small amount of hydroxyl and aldehyde compounds such as acetaldehyde, 2-methyl-propionaldehyde, 2-methyl-butyraldehyde, and formic acid, which were deduced as the material basis of the mildew. The results are expected to provide a basis for the rapid identification of Myristicae Semen with different degrees of mildew, odor changes, and the substance basis of mildew.

[Determination of each single component vegetable oil in blend oil by headspace gas chromatography-mass spectrometry].

OBJECTIVE: A method of headspace gas chromatography-mass spectrometry was established for the determination of the content of each single component vegetable oil in blend oil based on soybean oil, peanut oil and sesame oil. METHODS: The data of volatile components of each single component vegetable oil was collected effectively by headspace gas chromatography-mass spectrometry. The data was compared, filtered step by step and evaluated by method ology using chemometrics method and group analysis software. RESULTS: Finally, 2, 4-heptanedialdehyde, 2-decendialdehyde and 5-methyl-2-furfural were identified as the quantitative detection marker compounds of soybean oil, peanut oil and sesame oil, respectively. Dihydro-3-methylene-5-methyl-2-furanone and trans-2-nonenoldehyde, 4-ethyl-5-methyl-nonane and trans-2-dodecenol, 2-(1-pentenyl)-furan and 2-methylpyrazine were the qualitative compounds of soybean oil, peanut oil and sesame oil, respectively. The regression equations and linear correlation coefficient(r~2) of soybean oil, peanut oil and sesame oil were obtained by testing nine level simulated blend oil. The linear range were 0.57%-100%, 0.98%-100%, 0.34%-100%. The precision range were 1.4%-3.8%, 9.0%-16.0%, 5.0%-10.4%(n=6). The recovery range were 100.1%-100.5%, 75.0%-115.3%, 87.0%-100.6%. These data met the requirements of method ology. CONCLUSION: The method is applicable to testing research of the content of each single component vegetable oil in blend oil based on soybean oil, peanut oil and sesame oil.

[Determination of furan in canned foods and packaged beverages by headspace gas chromatography-mass spectrometry].

OBJECTIVE: A headspace gas chromatography-mass spectrometry(HS-GC-MS) method for the analysis of furan in canned foods and packaged beverages was established. METHODS: The furan was extracted from the samples by headspace method. D_4-furan was used as internal standard and separated on a HP-Plot Q(30 m×0.32 mm, 20 µm) column. The results were qualitative and quantitative by gas chromatography-mass spectrometry. RESULTS: The linear range of this method was 2.0-200.0 ng, and the regression equation of the working curve was y=1.14x +0.116(r~2=0.999). The recoveries were 86.3%-96.2% with the relative standard deviations(RSDs) less than 10%(n=6). The limit of quantification of furan was 1.0 ng. Through the detection of 59 samples, it was found that the common canned food and hard packaged drinks were commonly contaminated with furan, and the concentration of furan in coffee, milk tea, canned fish and other products were relatively high, with a maximum value of 153.99 ng. CONCLUSION: The method is simple, rapid, accurate and reliable, and could be used for the detection of furan in the two kinds of food.

High performance liquid chromatography fingerprint and headspace gas chromatography-mass spectrometry combined with chemometrics for the species authentication of Curcumae Rhizoma.

Curcumae Rhizoma (Ezhu), a multi-origin Chinese medicine, originates from the dry rhizomes of C. kwangsiensis, C. phaeocaulis and C. wenyujin. The three species have great variation in chemical components and therapeutic effects. To improve safety and effectiveness in clinical use, a strategy integrating chromatographic analysis and chemometrics for the species authentication of Ezhu was proposed. Firstly, systematic analysis of chemical compositions in Ezhu was achieved using high performance liquid chromatography (HPLC) fingerprint and headspace gas chromatography-mass spectrometry (HS-GC-MS). HPLC fingerprints showed that seventeen peaks in common for C. kwangsiensis and eleven peaks in common for C. wenyujin both presented a good similarity (> 0.9, only several samples < 0.8). Eleven common peaks in C. phaeocaulis and the similarity values of most samples were higher than 0.700. Additionally, there were ten common peaks in all Ezhu samples and they had relatively poor similarity with the correlation coefficients ranging from 0.364 to 0.881. For HS-GC-MS, thirty-six volatile components were identified in the three species of Ezhu, mainly monoterpenes and sesquiterpenes. Subsequently, chemometrics including unsupervised principal component analysis (PCA), supervised linear discriminant analysis (LDA), K-nearest neighbors (KNN), back propagation neural network (BP-NN) and orthogonal partial least squares-discrimination analysis (OPLS-DA) was applied to extract useful information from chromatographic profiles. Based on HPLC fingerprint data, PCA could hardly differentiate Ezhu with the three species, and LDA, KNN and BP-NN models provided more than 85 % correct identification. With HS-GC-MS data, PCA could only distinguish C. wenyujin from the other two species, and LDA, KNN, BP-NN and OPLS-DA models achieved excellent classification with 100 % accuracy. Finally, five volatile components (eucalyptol, humulene, ß-elemene, (+)-2-bornanone and linalool) with variable importance for the projection (VIP) values higher than 1 in the OPLS-DA model were selected as potential chemical markers for the species authentication of Ezhu. And the constructed OPLS-DA model using these markers obtained 100 % accuracy. Consequently, a rapid, precise and feasible strategy was established for the discrimination and quality control of Ezhu with different species.

Toward Nitrite-Free Curing: Evaluation of a New Approach to Distinguish Real Uncured Meat from Cured Meat Made with Nitrite.

After the International Agency for Research on Cancer (IARC) classified ingested nitrites and nitrates as "probably carcinogenic to humans" under conditions favoring endogenous nitrosation, several meat products labeled as "made without nitrite" were launched. In order to distinguish uncured products truly made without nitrite from cured products made with any nitrite source (vegetal or mineral), this article presents an approach to detect and quantify nitrite from different origins added to meat. The method consists on the determination of nitrous oxide as a target compound using headspace gas chromatography-mass spectrometry (HS-GC-MS). Nitrous oxide (N2O) is formed after two reduction steps: from nitrite to nitric oxide (NO) and then to N2O. The NO is bound to myoglobin (Mb) or metmyoglobin (Met-Mb), forming a complex, which is subsequently released using sulfuric acid, which also favors the reduction to N2O. The HS-GC-MS conditions were split ratio 1:10; injection temperature at 70 °C; incubation temperature at 30 °C and time 45 min; and injection volume 1 mL. As a result, a relationship was established between the concentration of nitrite in cooked ham samples and the area of the N2O peak generated, meaning that this method allows the quantification of added nitrite within a concentration range of 10 to 100 mg kg-1.

Configuration of the Volatile Aromatic Profile of Carob Powder Milled From Pods of Genetic Variants Harvested at Progressive Stages of Ripening From High and Low Altitudes.

Carob powder is increasingly valued as a substitute for cocoa and as a flavor-enhancing component of processed foods. However, little is known about the impact of preharvest factors such as fruit maturity, genotype and altitude on its volatile organic compounds (VOCs) composition. The current study examined the VOCs composition of powder milled from pods of two genotypes cultivated at 15 and 510 m altitude and harvested at six progressive stages of maturity, ranging from fully developed immature green (RS1) to late ripe (RS6). Fifty-six VOCs categorized into acids, esters, aldehydes, ketones, alcohols, furans, and alkanes were identified through HS-SPME GC-MS analysis. Maturity was the most influential factor, followed by altitude and least by genotype. Aldehydes and alcohols correlated positively (r = 0.789; p < 0.001), both accumulated in immature carobs and decreased with progressive ripening, resulting in the attenuation of green grassy aroma. Conversely, acids increased with ripening and dominated the carob volatilome at full maturity, correlating negatively with aldehydes and alcohols (r = -0.835 and r = -0.950, respectively; p < 0.001). The most abundant VOC throughout ripening (17.3-57.7%) was isobutyric acid, responsible for the characteristic cheesy-acidic-buttery aroma of carob powder. The pleasurable aroma detected at the immature stages (RS2 and RS3) was traced to isobutyrate and methyl isobutyrate esters, rendering unripe green carob powder a potential admixture component for improving the aroma of novel food products. Lower altitude favored the accumulation of acids linked to less pleasant aroma, whereas isobutyric acid was more abundant at higher altitude. This constitutes a significant indication that higher altitude enhances the characteristic carob-like aroma and sensory quality of carob powder.

[Determination of 1, 4-dioxane in aerosol cosmetic by new isotope dilution-headspace gas chromatography-mass spectrometry].

OBJECTIVE: To develop a simple, fast and sensitive analytical method based on isotope dilution-headspace gas chromatography-mass spectrometry for the determination of 1, 4-dioxane residue in the aerosol cosmetics. METHODS: Sample was successive weighed and dissolved in 1, 3-dimehyl-2-imidazolidinone(DMI)solvent and isotope internal standard was added. Then transfered to a 20 mL headspace vial. The headspace vial was sealed and extracted 15 min by ultrasonic-assisted extraction. After separated by HP-5 MS fused silica capillary column(30 m×25 mm, 0. 25 µm), the compound was analyzed by gas chromatography-mass spectrometry in selected ion monitoring mode(GC-MS-SIM) and quantified by internal standard method. RESULTS: There were good linear correlations with R~2 no less than 0. 999 in the range of 1. 0-100 mg/kg. The limit of detection(LOD) of this method was 0. 3 mg/kg. At 0. 3, 1. 0, 5. 0 and 30 mg/kg four added concentration, recovery for five kinds of aerosol cosmetic were all between 91. 4% and 104. 2%. The relative standard deviations(RSDs) were 1. 5%-6. 3% and 1. 7%-6. 4%(n=6), respectively. CONCLUSION: The developed method has proved convenient, time-saving, accurate and sensitive and suited for determination 1, 4-dioxane in aerosol cosmetic.

[Determination and classification of flammable liquids by headspace gas chromatography-mass spectrometry].

An effective method was established for the determination and classification of flammable liquids by headspace gas chromatography-mass spectrometry (HS-GC-MS). The volatile components, equilibrium temperature and equilibrium time of gravure ink were investigated. The volatile components of flammable liquids were identified by comparison with the standard mass spectrum databases, and quantified by the external standard method. The recoveries were in the range of 92.8%-103.1% with the relative standard deviations between 0.88% and 2.88%. The flash points of the samples were calculated by a prediction model and compared with the experimentally measured values. The results showed that the maximum deviation between the predicted and measured flash points was 3.2℃. This method provides a novel, efficient and convenient way for the classification of flammable liquids.

Assay of dried blood spot from finger prick for sodium valproate via ink auxiliary headspace gas chromatography mass spectrometry.

Sodium valproate is the most commonly used antiepileptic drug that patients need to keep taking over a long period of time or on a permanent basis. Its blood concentration should be accurately detected to avoid toxicity or side-effects, especially for children and the aged. Dried blood spot (DBS) sampling from finger prick is a minimally invasive and patient-friendly procedure for blood collection. However, there are few studies about rapid detection of sodium valproate in DBS samples in current literatures. In this work, we developed an ink auxiliary headspace gas chromatography mass spectrometry (GC-MS) strategy for direct detection of sodium valproate in DBS from epilepsy patients, which does not need extra solvent extraction or elution. It was discovered that carbon black ink could provide better capacity of heat absorption and dissociation, and higher quality of headspace sampling. The detection sensitivity has been improved with reported headspace GC-MS methods, and the limit of quantitation could reach to 200 ng/mL. Finally, this strategy was practically applied to quantify sodium valproate in DBS samples from 29 epilepsy patients. The result showed higher accuracy with lower relative errors by comparing with the clinical immunoassay results. In conclusion, we developed a direct detection method for DBS samples that is suitable for high-throughput clinical test with great potential for clinical application.

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, ß-elemene, ß-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.

[Simultaneous determination of 27 solvent residuals in ultraviolet curable offset inks by headspace gas chromatography-mass spectrometry].

A headspace gas chromatography-mass spectrometry (HS-GC-MS) method was developed for the determination of 27 solvent residuals (volatile organic compounds, VOCs) in ultraviolet (UV) curable offset inks. Ink samples of a given area and thickness were prepared using an ink-scraping instrument and baked under a UV lamp for 1 min. The experimental conditions such as headspace temperature and time, and the GC-MS analytical conditions, were optimized. The ink samples were treated at 80℃ for 45 min, and the evolved products were separated on a special VOC column, identified by MS, and quantified by an external-standard method. The calibration curves for all 27 VOCs showed good linearity with correlation coefficients (R2) no lower than 0.9950. The limits of detection (S/N=3) were in the range of 0.001-0.310 mg/m2 and the limits of quantification (S/N=10) were in the range of 0.003-0.920 mg/m2. The average recoveries of the 27 VOCs ranged from 80% to 108% at various spiked levels, with relative standard deviations less than 6% (n=6). Thus, this method has a high sensitivity and good precision and accuracy, and it is suitable for the determination of 27 solvent residuals in various UV offset inks.