Fumigant Activity of Bacterial Volatile Organic Compounds against the Nematodes Caenorhabditis elegans and Meloidogyne incognita

Plant-parasitic nematodes infect a diversity of crops, resulting in severe economic losses in agriculture. Microbial volatile organic compounds (VOCs) are potential agents to control plant-parasitic nematodes and other pests. In this study, VOCs emitted by a dozen bacterial strains were analyzed using solid-phase microextraction followed by gas chromatography–mass spectrometry. Fumigant toxicity of selected VOCs, including dimethyl disulfide (DMDS), 2-butanone, 2-pentanone, 2-nonanone, 2-undecanone, anisole, 2,5-dimethylfuran, glyoxylic acid, and S-methyl thioacetate (MTA) was then tested against Caenorhabditis elegans. DMDS and MTA exhibited much stronger fumigant toxicity than the others. Probit analysis suggested that the values of LC₅₀ were 8.57 and 1.43 μg/cm³ air for DMDS and MTA, respectively. MTA also showed stronger fumigant toxicity than DMDS against the root-knot nematode Meloidogyne incognita, suggesting the application potential of MTA.     

Optimization of SPME-Arrow-GC/MS Method for Determination of Free and Bound Volatile Organic Compounds from Grape Skins

(1) Background: Solid phase microextraction (SPME)-Arrow is a new extraction technology recently employed in the analysis of volatiles in food materials. Grape volatile organic compounds (VOC) have a crucial role in the winemaking industry due to their sensory characteristics of wine.; (2) Methods: Box–Behnken experimental design and response surface methodology were used to optimise SPME-Arrow conditions (extraction temperature, incubation time, exposure time, desorption time). Analyzed VOCs were free VOCs directly from grape skins and bound VOCs released from grape skins by acid hydrolysis.; (3) Results: The most significant factors were extraction temperature and exposure time for both free and bound VOCs. For both factors, an increase in their values positively affected the extraction efficiency for almost all classes of VOCs. For free VOCs, the optimum extraction conditions are: extraction temperature 60 °C, incubation time 20 min, exposure time 49 min, and desorption time 7 min, while for the bound VOCs are: extraction temperature 60 °C, incubation time 20 min, exposure time 60 min, desorption time 7 min.; (4) Conclusions: Application of the optimized method provides a powerful tool in the analysis of major classes of volatile organic compounds from grape skins, which can be applied to a large number of samples.     

Identification and Biological Activity of Volatile Organic Compounds Isolated from Plants and Insects. III. Chromatography-Mass Spectrometry of Volatile Compounds of Aegopodium podagraria

Gas chromatography-mass spectrometry identified more than 20 volatile organic compounds isolated from leaves and flowers ofAegopodium podagrariaL.     

挥发性和半挥发性有机物向二次有机气溶胶转化的机制

从近20年二次有机气溶胶形成机制的研究成果可发现,挥发性和半挥发性有机物转化为二次有机气溶胶的主要物理化学过程可概述为光化学氧化机制、成核过程、凝结和气/粒分配机制以及非均相反应机制。本文系统总结了这些物理化学反应的发生过程及其影响因素,重点阐述了异戊二烯和甲苯同系物的光氧化机制,总结了二次有机气溶胶气/粒分配的两种理论--吸收机制和吸附机制,评述了发生在颗粒相上的非均相反应对二次有机气溶胶形成的重要作用。最后,对二次有机气溶胶形成机制研究的发展方向进行了展望。     

Discrimination and Characterization of the Volatile Organic Compounds in Schizonepetae Spica from Six Regions of China Using HS-GC-IMS and HS-SPME-GC-MS

Volatile organic compounds (VOCs) are the main chemical components of Schizonepetae Spica (SS), which have positive effects on the quality evaluation of SS. In this study, HS-SPME-GC-MS (headspace solid-phase microextraction-gas chromatography-mass spectrometry) and HS-GC-IMS (headspace-gas chromatography-ion mobility spectrometry) were performed to characterize the VOCs of SS from six different regions. A total of 82 VOCs were identified. In addition, this work compared the suitability of two instruments to distinguish SS from different habitats. The regional classification using orthogonal partial least squares discriminant analysis (OPLS-DA) shows that the HS-GC-IMS method can classify samples better than the HS-SPME-GC-MS. This study provided a reference method for identification of the SS from different origins.     

Microchamber Extraction and Analytical Pyrolysis to Explore Volatile Organic Compounds from Compression-Cooking Wood Materials Obtained under Different Conditions

Volatile organic compounds are species of concern for indoor air quality. They are emitted from a wide range of indoor sources and in particular from construction materials. Industrialized wood-based panels made from various types of wood bonded with thermosetting adhesive resins have been shown to emit volatile organic compounds over months or even years mostly due to the petrochemical binders. Some studies have been conducted on binderless panels, but they mainly focused on the pressing parameters to be applied to optimize the panel characteristics. The aim of this research is to document the emissions from binderless panels and to access the volatile composition of wood processing through the molding of materials. For this purpose, binderless boards were manufactured from hardwoods, known to emit less than softwoods with different thermopressing temperatures and times. Emissions were studied by placing the materials in microchambers. Volatile organic compounds were then sampled and analyzed by various chromatographic methods. On the other hand, materials were pyrolyzed and then analyzed by gas chromatography and mass spectrometry. The implemented protocols proved suitable for the determination of more than 40 organic compounds, among which are aldehydes, aromatics, furans and derivatives, and carboxylic acids.     

Rational Design of Peptides Derived from Odorant-Binding Proteins for SARS-CoV-2-Related Volatile Organic Compounds Recognition

Peptides are promising molecular-binding elements and have attracted great interest in novel biosensor development. In this study, a series of peptides derived from odorant-binding proteins (OBPs) were rationally designed for recognition of SARS-CoV-2-related volatile organic compounds (VOCs). Ethanol, nonanal, benzaldehyde, acetic acid, and acetone were selected as representative VOCs in the exhaled breath during the COVID-19 infection. Computational docking and prediction tools were utilized for OBPs peptide characterization and analysis. Multiple parameters, including the docking model, binding affinity, sequence specification, and structural folding, were investigated. The results demonstrated a rational, rapid, and efficient approach for designing breath-borne VOC-recognition peptides, which could further improve the biosensor performance for pioneering COVID-19 screening and many other applications.     

Membrane Extraction of Volatile Organic Compounds in Combination with Mobile Gas Chromatographic Analysis

Abstract

The field of application of a mobile gas chromatographic device (Airmobtx monitor HC 1000 manufactured by Airmotec GmbH) originally conceived for the analysis of BTEX in air was extended to water analysis by using it in conjunction with membrane extraction. Volatile organic compounds diffuse out of water through a hollow fibre or flat membrane, are enriched onto sorption tubes integrated in the device, and then thermally desorbed and analysed by the gas chromatograph/flame ionisation detector. The suitability of various flat membranes and hollow fibres was investigated. Maximum extraction efficiency was obtained with a silicone hollow fibre measuring 0.3 m long, and with an inner diameter of 0.7 mm and a wall thickness of 100 μm. The extraction parameters were optimised. The linear dynamic range of the optimised method spans two orders of magnitude and the detection limits were found to be 0.1 μg/L for all BTEX compounds. By way of environmental applications, highly contaminated groundwater samples were analysed. The results correspond well to those achieved using conventional headspace/gas chromatography/flame ionisation detection.     

Research on Very Volatile Organic Compounds and Odors from Veneered Medium Density Fiberboard Coated with Water-Based Lacquers

Very volatile organic compounds (VVOCs) are a group of important odor pollutants affecting indoor air quality that have been shown to be harmful to human health. A 15 L environmental chamber, combined with multi-bed tube was used to collect gases. Fifteen very volatile organic compounds (VVOCs), including 12 odor compounds, were identified from veneered medium density fiberboard coated with water-based lacquer (WB-MDF) using gas chromatography–mass spectrometry/olfactometry (GC-MS/O). The total very volatile organic compound (TVVOC) and total odor intensity (TOI) showed a decreasing trend over time, reaching equilibrium on day 28. TVVOC showed an overall slow-fast-slow emission profile, from day 3 to day 7, with a maximum decay rate of 29.7%. TOI showed the greatest rate of decline from day 1 to day 3, at approximately 12%. Alkane and alcohol VVOCs were the more abundant compounds, accounting for at least 60% and even up to 80% of the total. The major odor impression was fruity, with a highest odor rating of 6.6, followed by sweet, with an odor rating of 6.1. Although the odor impression changed from sweet to fruity over time, it seemed pleasant overall. The odor contributors were mainly alkanes, alcohols, esters, and ethers, which had relatively high odor intensities. The main odor-contributing substances were dichloromethane, ethanol, ethyl acetate, 2-methylacrylic acid methyl ester, and tetrahydrofuran. When WB-MDF is used for furniture or other decorative materials, it is strongly recommended that it be stored under ventilation for at least 28 days and the adoption of substitute solvents of lacquers, modified adhesives, and low-odor wood raw materials is recommended. These possible initiatives would contribute to the aim of building an environmentally friendly indoor environment.     

主成分-线性判别法对大气易挥发性有机化合物的预警

应用遥感傅里叶变换红外光谱,采用主成分提取-线性判别分析(PCA-LDA)技术,对丙酮、二氯甲烷、甲苯、苯、氯仿和甲醇等六组分的任意混合体系进行定性鉴别。被选用的这6种大气有毒有机化合物的红外光谱图相互间存在着严重的混叠,并和反向传播人工神经网络(BP-ANN)的预测结果进行了比较。PCA-LDA的鉴别判对率达92.2%,识别率94.4%,误判率7.8%;BP-ANN分别为91.1%、95.6%和8.9%。结果表明PCA处理克服了LDA对多变量数据预测的局限性,预测性能和BP-ANN相当。鉴于BP-ANN计算耗时和繁琐,PCA-LDA模型被确定为建立VOCs预警模型最适当的方法。     

Membrane Extraction Combined with Thermodesorption/Gas Chromatography and Mass Selective Detection for the Analysis of Volatile Organic Compounds in Water

The range of application of a commercial thermodesorption-cryofocussing unit connected to a gas chromatograph/mass selective detector was extended to water analysis by using it in conjunction with membrane extraction. A flow of nitrogen passes through a silicone hollow fiber immersed in the water sample and extracted volatile organic compounds are enriched in a sorption tube mounted on top of the extraction cell. The sorption tube is then placed in the thermodesorption unit and analyzed by GC/MS. The optimal extraction parameters of this combined method were found to be 30 min extraction at 20°C with a stirring speed of 1,250 rpm and a flow rate of 100 mL/min nitrogen using a silicone hollow fiber of 0.3 m length. Under these conditions the reproducibility of the method was 5.2–10.5% RSD. The linear dynamic range of the optimized method spans three orders of magnitude and detection limits were found to be 0.02–0.1 μg/L for cis/trans-1,2-dichloroethene, benzene, trichloroethene, chlorobenzene, bromobenzene, ethylbenzene, 1,1,2,2-tetrachloroethane, and 1,2/1,4-dichlorobenzene. The method was found to be suitable for compounds with boiling points up to 220°C as memory effects increased considerably from dichloro- to hexachlorobenzene. Highly contaminated groundwater samples were analyzed. Quantitative results corresponded well with those achieved with conventional headspace-GC/FID.     

Identification and Biological Activity of Volatile Organic Compounds Emitted by Plants and Insects. IV. Composition of Vapor Isolated from Certain Species of Artemisia Plants

The components of fragrance from four wormwood species of theArtemisiaL. genus were analyzed by GC-MS. The major and minor components of volatile essential oils typical of the studied plant species were determined.     

荧光衍生化-磁分散固相萃取/高效液相色谱检测池塘水与蔬菜中3种挥发性异味物质

以6-碳酰氯左氧氟沙星(LFC-Cl)为衍生试剂,磁性氧化石墨烯(MGO)为吸附剂,建立了2-甲基异莰醇(2-MIB)、土臭素(GSM)和3-甲基-1-丁醇(3-MB)的高效液相色谱荧光检测(HPLC-FLD)分析方法。在浓度为0.05 mol/L的4-二甲氨基吡啶(DMAP)乙腈溶液中,衍生温度60℃,反应时间90 min,超声波辅助条件下,可完成上述3种醇类挥发性异味物质(VOCs)的衍生化。在吸附剂用量20 mg、萃取时间20 min、解吸剂为乙腈(含1%甲酸)、解吸时间3 min条件下,能实现3种异味物质衍生物的富集和净化。在优化的HPLC条件下,15 min内可实现3种衍生物的基线分离和高灵敏检测。方法检出限(LOD)为0.020～0.95 ng/L,定量下限(LOQ)为0.10～3.3 ng/L,线性、精密度和回收率良好。与已报道的方法相比,该方法具有灵敏度高、样品前处理简单、仪器普适性好等优势,可用于池塘水、蔬菜中VOCs的快速、定量测定,为食品和环境水样监测提供了一种新方法。     

顶空固相微萃取-气相色谱/质谱法分析鉴定畜禽粪便中的挥发性有机化合物

采用顶空固相微萃取(HS-SPME)-气相色谱/质谱法(GC/MS)测定了牛粪、猪粪以及鸡粪中的挥发性有机化合物(VOCs)。在优化HS-SPME条件的基础上,通过GC/MS分析,从牛粪中分离鉴定出44种VOCs,从猪粪中分离鉴定出40种VOCs,从鸡粪中分离鉴定出41种VOCs。HS-SPME-GC/MS具有简单、快速、无需有机溶剂等特点,适合于畜禽粪便中挥发性有机化合物的分析与鉴定。同时,该研究揭示了畜禽养殖场臭味物质的来源,为治理其环境污染提供了科学依据。     

顶空固相微萃取/气相色谱-三重四极杆串联质谱法测定地表水与饮用水中的挥发性有机物

采用部分因子试验设计筛选出顶空固相微萃取的主要影响参数,利用中心复合设计对主要影响参数的取值进行了优化,建立了顶空固相微萃取(HS-SPME)结合气相色谱-三重四极杆串联质谱(GC-MS/MS)测定地表水和饮用水中55种挥发性有机物(VOCs)的分析方法。取5.0 mL样品于顶空瓶中,加入0.75 g NaCl,使用CAR/PDMS 75μm纤维头,萃取温度40℃,萃取时间40 min,解析温度300℃,在GC-MS/MS选择反应监测(SRM)模式下检测,内标法定量。结果表明,55种VOCs在0.04～0.40、0.4～4.0、4.0～100μg/L质量浓度范围内线性良好,相关系数(r~2)均大于0.99,方法的检出限为0.03～80 ng/L,定量下限为0.1～300 ng/L。55种VOCs在0.2、2.0、40μg/L 3个加标水平下的平均回收率为77.3%～124%,相对标准偏差(RSD,n=6)为1.3%～17%。对3种地表水和3种饮用水进行测定,地表水中有37种VOCs被检出,饮用水中有25种VOCs被检出。实验证明,建立的HS-SPME和GC-MS/MS相结合的检测方法具有准确可靠、简单快速、灵敏度高等优点,适用于地表水和饮用水中VOCs的同时测定。