Automatic Thermal Desorption/gas Chromatography/mass Spectrometry Research Articles

Aroma Components Analysis and Origin Differentiation of Black Tea Based on ATD-GC-MS and E-Nose

Black tea (Fuyun 6) samples collected from three regions, Youxi, Fu’an, and Datian, were analysed by automatic thermal desorption-gas chromatography–mass spectrometry (ATD-GC–MS) combined with the electronic nose (E-nose) technique to investigate the aroma composition differences between black teas from different regions. The response surface methodology was used to optimize the ATD conditions for extracting the aroma components from the black tea. The results revealed that the optimal conditions for aroma component accumulation from black tea samples included a sample weight of 2.8 g, an adsorption time of 39 min, an adsorption temperature of 75 °C, and a cold trap temperature of −30 °C. The ATD-GC–MS analyses identified a total of 71 aroma components in the black tea samples, of which 31 were utilized to differentiate the origins of the black teas. Additional aroma activity analyses indicated that benzyl alcohol, linalool, hexanal, octanal, and nonanal had odour activity values (OAVs) greater than 10. Additionally, the OAV of decanal exceeded 100, indicating its significant contribution to the aroma profile of Fuyun 6 black tea. The E-nose results demonstrated the ability to differentiate the black tea samples from the three different origins. This study successfully identified the specific aroma substances associated with different tea origins, providing valuable insights into the aroma characteristics of black teas from various regions.

Comparison of Volatiles in Different Jasmine Tea Grade Samples Using Electronic Nose and Automatic Thermal Desorption-Gas Chromatography-Mass Spectrometry Followed by Multivariate Statistical Analysis.

Chinese jasmine tea is a type of flower-scented tea, which is produced by mixing green tea with the Jasminum sambac flower repeatedly. Both the total amount and composition of volatiles absorbed from the Jasminum sambac flower are mostly responsible for its sensory quality grade. This study aims to compare volatile organic compound (VOC) differences in authoritative jasmine tea grade samples. Automatic thermal desorption-gas-chromatography-mass spectrometry (ATD-GC-MS) and electronic nose (E-nose), followed by multivariate data analysis is conducted. Consequently, specific VOCs with a positive or negative correlation to the grades are screened out. Partial least squares-discriminant analysis (PLS-DA) and hierarchical cluster analysis (HCA) show a satisfactory discriminant effect on rank. It is intriguing to find that the E-nose is good at distinguishing the grade difference caused by VOC concentrations but is deficient in identifying essential aromas that attribute to the unique characteristics of excellent grade jasmine tea.

Identification of Floral Fragrances and Analysis of Fragrance Patterns in Herbaceous Peony Cultivars

Thirty herbaceous peony (section Paeonia of the genus Paeonia) cultivars were divided into four groups (no fragrance, light fragrance, medium fragrance, or intense fragrance) based on their sensory evaluation scores. Using dynamic headspace sampling (DHS) and automatic thermal desorption–gas chromatography/mass spectrometry (ATD-GC/MS), 130 volatile organic components were detected in these 30 cultivars and a total of 72 compounds were identified as scent components. The main compounds were phenylethyl alcohol, β-caryophyllene, linalool, (R)-citronellol, and nerol. Selecting α-pinene as the standard, the volatile components of these cultivars were quantitatively analyzed. By combining the sensory evaluation scores and the results of quantitative analysis, we found that ‘Going Bananas’, ‘Cream Delight’, ‘Zhu Sha Pan’, ‘Qiao Ling’, ‘Duchess de Nemours’, and ‘Yang Fei Chu Yu’ displayed an intense fragrance and, thus, had relatively high commercial value for the flower fragrance industry. ‘Red Magic’, ‘Joker’, ‘Fairy Princess’, ‘Lovely Rose’, ‘Carina’, and ‘Etched Salmon’ were excluded from the hierarchical cluster of aromatic compounds and the analysis of fragrance patterns because of the low amount of fragrance they released and poor sensory evaluation results. Based on a cluster analysis, assessment of the major aromatic compounds, and the results of sensory evaluation, the remaining 24 cultivars were divided into five fragrance patterns for the first time: woody scent [cluster I (major fragrance β-caryophyllene)], fruity scent [cluster II (phenylethyl alcohol)], lily scent [cluster III (linalool)], rose scent {cluster IV [(R)-citronellol]}, and an orange blossom scent [cluster V (nerol)].

Identifi cation of Volatile Compounds Emitted by Artemisia ordosica (Artemisia, Asteraceae) and Changes due to Mechanical Damage and Weevil Infestation

Volatiles emitted by healthy, mechanically damaged, and weevil-infested Artemisia ordosica (Asteraceae) were obtained through a dynamic headspace method and analysed by automatic thermal desorption/gas chromatography/mass spectrometry (ATD/GC/MS). Twenty-eight compounds in all were identified, and the qualitative as well as quantitative differences were compared. The green leaf volatiles 2-hexenal, (Z)-3-hexen-1-ol, 2-hexen-1-ol, 1-hexanol, and (Z)-3-hexen-1-ol acetate were present in all of the damaged plants, but in relatively lower portions when plants were infested by the weevil Adosopius sp., while the terpenoids α-copaene, β-cedrene, and (E,E)-α-farnesene and the ester methyl salicylate were only present in weevildamaged plants. The volatiles from healthy and weevil-infested leaves were dominated by D-limonene, whereas mechanically damaged leaves emitted β-pinene as the dominant compound

Comparative Study of the Volatiles’ Composition of Healthy and Larvae-Infested Artemisia ordosica

Volatiles emitted by healthy Artemisia ordosica (Asteraceae) and plants infested with larvae of Sphenoptera sp. (Coleoptera: Buprestidae) or Holcocerus artemisiae (Lepidoptera: Cossidae) were obtained using a dynamic headspace method and analysed by automatic thermal desorption/gas chromatography/mass spectrometry (ATD/GC/MS). Twenty-eight major compounds were identified, and qualitative and quantitative differences were compared. The novel green leaf volatiles 2-hexenal, (Z)-3-hexen-1-ol, 2-hexen-1-ol 1-hexanol, and (Z)-3-hexen-1-ol acetate, the terpenoids alpha-copaene, beta-cedrene, and (E,E)-alpha-farnesene, and the ester methyl salicylate were present in all infested plants. Volatiles from healthy plants were dominated by D-limonene (32.14%), beta-pinene (16.63%), beta-phellandrene (16.06%), and sabinene (12.88%). Volatiles from Sphenoptera sp. larvae-infested plants were dominated by D-limonene (24.74%), beta-pinene (21.05%), alpha-pinene (19.39%), and sabinene (11.64%), whereas volatiles from H. artemisiae larvae-infested plants were dominated by D-limonene (31.76%), sabinene (18.49%), ocimene (15.93%), and beta-phellandrene (10.59%). In addition to the qualitative variation, a larvae-induced quantitative change in the proportion of terpenoids in the blends was also a noticeable feature.

Identifi cation of Volatile Compounds Emitted by Artemisia ordosica (Artemisia, Asteraceae) and Changes due to Mechanical Damage and Weevil Infestation

Volatiles emitted by healthy, mechanically damaged, and weevil-infested Artemisia ordosica (Asteraceae) were obtained through a dynamic headspace method and analysed by automatic thermal desorption/gas chromatography/mass spectrometry (ATD/GC/MS). Twenty-eight compounds in all were identified, and the qualitative as well as quantitative differences were compared. The green leaf volatiles 2-hexenal, (Z)-3-hexen-1-ol, 2-hexen-1-ol, 1-hexanol, and (Z)-3-hexen-1-ol acetate were present in all of the damaged plants, but in relatively lower portions when plants were infested by the weevil Adosopius sp., while the terpenoids alpha-copaene, beta-cedrene, and (E,E)-alpha-farnesene and the ester methyl salicylate were only present in weevil-damaged plants. The volatiles from healthy and weevil-infested leaves were dominated by D-limonene, whereas mechanically damaged leaves emitted beta-pinene as the dominant compound.

In vitro cytotoxicity and morphological assessment of smoke from polymer combustion in human lung derived cells (A549)

The application of polymer and composites in building and modern transport interiors raises concerns of potential health hazards during combustion. Cytotoxicity and morphological assessment of smoke from polymer combustion in human lung derived cells (A549) has been investigated. A laboratory scale vertical tube furnace was used for the generation of combustion products. A range of materials used in the building and transport industry including high density-polyethylene (HDPE), polypropylene (PP), polycarbonate (PC), and polyvinyl chloride (PVC), fiberglass reinforced polymers (FRPs), and melamine faced plywood (MFP) were studied. The exposure of combustion toxicants to human lung cells (A549) at the air/liquid interface was acquired using a Harvard Navicyte Chamber. Cytotoxic effects on human cells were assessed based on cell viability using a selected in vitro cytotoxicity assays, including NRU (neutral red uptake) and ATP (adenosine triphosphate). Morphological assessment on the effects of combustion products in human lung cells from selected materials including PVC, FRP and MFP was assessed using scanning electron microscopy (SEM). The volatile organic compounds from thermal decomposition products were identified using ATD-GCMS (Automatic Thermal Desorption Gas Chromatography Mass Spectrometry). NOAEC (No Observable Adverse Effect Concentration), IC(10) (10% inhibitory concentration), IC(50) (50% inhibitory concentration), and TLC (Total Lethal Concentration) values (mg/l) were generated. The following toxicity ranking was observed from the most toxic material to the least toxic using the NRU assay: PVC>PP>HDPE>PC >FRP-10>MFP>FRP-16; and the ATP assay: PVC>HDPE>PP>FRP-10>FRP-16>MFP>PC. The method described here could potentially be an alternative to current fire toxicity standards.

Genotoxic effects of volatile organic compounds in a chemical factory as evaluated by the Tradescantia micronucleus assay and by chemical analysis

The clastogenic effects of volatile organic compounds in the workplace air of a chemical factory were studied by means of the Tradescantia micronucleus (Trad-MCN) assay and chemical analysis. Sampling was performed at a chemical factory producing PVC film in Cheong-ju, South Korea. Inflorescences of Tradescantia BNL 4430 were placed for 2, 6, and 9 h at the height of 1.40 m at two locations in the workplace and one outdoor of the chemical industry. Air samplings were conducted in the same places and the collected tube samples were analyzed by automatic thermal desorption/gas chromatography/mass spectrometry (ATD/GC/MS). The frequencies of micronuclei in specimens exposed for 2 h in sites 1–3 were 6.13±0.47, 5.40±1.60, and 2.93±0.43 MCN per 100 tetrads, respectively. GC/MS analysis proved the presence of various volatile organic compounds such as trichloroethylene, toluene, ethyl benzene, ( m, p, o)-xylene, styrene, 1,3,5-trimethyl benzene, and 1,2,4-trimethyl benzene. Mean values of toluene measured by 2 h sampling in sites 1–3 were 1946.6, 1368.3, and 340.1 μg/m 3, respectively. The toluene concentrations in sites 1 and 2 were at least four to six times higher than that in site 3. The micronucleus frequencies increased with exposure time. In addition, there was a correlation between the micronucleus frequencies and toluene concentration in the air ( R 2=0.96). The results of this in situ monitoring proved the applicability of the Trad-MCN assay combined with chemical analysis for monitoring genotoxic chemicals in the work environment.

Retrospective identification of chemical warfare agents by high-temperature automatic thermal desorption–gas chromatography–mass spectrometry

An automated thermal desorption (ATD)–gas chromatography–mass spectrometry method was developed for the analysis of selected chemical warfare (CW) agents. Suitable methods were developed for analytes of high volatility to low volatility. The less volatile CW agents required the purchase and installation of a high-temperature valve upgrade kit allowing valve temperatures of up to 260°C to be reached. The limit of detection was 50 ng on the tube for most CW agents in full scan. Chloropicrin exhibited some temperature dependence, with detection limits improving as ATD temperatures were decreased below 150°C. A sample storage trial was undertaken to establish the most suitable storage environment for CW agents adsorbed onto Tenax TA. Temperature and time of storage were found to influence recovery of analytes with best recoveries being observed after 1 day storage in a freezer (−12°C). This method was evaluated during a trial of procedures for sampling and identification of chemical agents at Porton Down, UK. Sulfur mustard was detected downwind of a simulated exploded munition.

Direct analysis of oligomeric tackifying resins in rubber compounds by automatic thermal desorption gas chromatography/mass spectrometry

Two analytical methods, automatic thermal desorption gas chromatography/mass spectrometry (ATD-GC/MS) and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS), were applied as direct methods for the analysis of oligomeric tackifying resins in a vulcanized rubber. The ATD-GC/MS method, based on discontinuous volatile extraction, was found to be an effective means for direct analysis of the oligomeric tackifying resins contained in a vulcanized rubber. The oligomeric tackifying resins, such as t-octylphenolformaldehyde (TOPF) resin, rosin-modified terpene resin, and cashew resin, could be directly analyzed in vulcanized rubber by ATD-GC/MS. Much simpler total ion chromatograms were obtained by ATD-GC/MS than by flash pyrolysis with a Curie-point pyrolyzer, permitting much easier interpretation. Ions at m/z 206, 135, and 107 were fingerprints in the characteristic mass spectra obtained by ATD-GC/MS for TOPF resin in the vulcanized rubber. 1H-Indene, styrene, and isolongifolene were observed as their characteristic mass spectra in the pyrolyzate of the rosin-modified terpene resin. From the cashew resin, phenol, 3-methylphenol, and 4-(1,1,3, 3-tetramethylbutyl)phenol were obtained as the characteristic pyrolyzates by discontinuous thermal extraction via ATD-GC/MS. Copyright 1999 John Wiley & Sons, Ltd.