纺织品有机挥发物的测定

采用直接顶空进样和顶空-固相微萃取进样的方法，以测定纺织品中有机挥发物的含量，由气相色谱-质谱联用仪进行定性分析，外标法进行定量分析。本方法对目标化合物的检测限低于0．005mg／kg，加标回收率在88％～97％，相对标准偏差小于9％。     

Production of volatile organic compounds by apples

There is great variation in the rate at which different apple cultivars produce volatiles. The rate of production of volatiles, in terms of loss of carbon, is some 0.3–1.0% of the loss of CO₂; depending on conditions of storage, some 50–95% of the carbon lost as volatiles is accounted for by ethylene. Increase in concentration of CO₂ in the storage atmosphere reduces the rate of production of volatiles. Reduction of the oxygen concentration to a low level has the same effect, and ethylene production ceases in the complete absence of oxygen. The peel of the fruit is more active in production of ethylene than is the pulp; the rate of production is greater for small apples than for large. When the volatiles are removed from the storage atmosphere, the rate of production increases. The incidence of superficial scald, and the shape of the time/rate graph for ethylene are related. This could be due to an effect of climate during the growing period, affecting the porosity of the peel.     

Production of volatile organic compounds by pears

There is considerable variation between the rates of production of volatile organic compounds by different cultivars of pears, as has been shown for apples; the rates are lower in controlled atmosphere (C.A. ) storage than in air. When pears which have been cold stored, in air or in C.A. are ripened at a higher temperature, the rate of evolution of ethylene rises rapidly to a high value, but subsequently declines as the pears develop overripe symptoms.     

Source apportionment of ambient volatile organic compounds in Beijing

The ambient air quality standard for ozone is frequently exceeded in Beijing in summer and autumn. Source apportionments of volatile organic compounds (VOCs), which are precursors of ground-level ozone formation, can be helpful to the further study of tropospheric ozone formation. In this study, ambient concentrations of VOCs were continuously measured with a time resolution of 30 min in August 2005 in Beijing. By using positive matrix factorization (PMF), eight sources for the selected VOC species were extracted. Gasoline-related emissions (the combination of gasoline exhaust and gas vapor), petrochemicals, and liquefied petroleum gas (LPG) contributed 52, 20, and 11%, respectively, to total ambient VOCs. VOC emissions from natural gas (5%), painting (5%), diesel vehicles (3%), and biogenic emissions (2%) were also identified. The gasoline-related, petrochemical, and biogenic sources were estimated to be the major contributors to ozone formation potentials in Beijing.     

Analysis of volatile organic compounds in mainstream cigarette smoke

Mainstream cigarette smoke is a complex aerosol containing more than 4400 chemicals. The proliferation of new brands has necessitated development of faster and more reliable methods capable of analyzing a wide range of compounds in cigarette smoke. Although the International Agency for Research on Cancer has classified whole cigarette smoke as a human carcinogen, many of the individual chemicals are themselves highly biologically active as carcinogens, teratogens, or have implications for cardiovascular disease. Among these chemicals are many volatile organic compounds (VOCs), e.g., benzene, ethylbenzene, and styrene. To analyze VOCs in mainstream cigarette smoke, we developed a novel headspace collection technique using polyvinylfluoride bags for sample collection followed by cannula transfer to evacuated standard 20-mL auto sampler vials. Coupling collection of the vapor-phase cigarette smoke with automated analysis by solid-phase microextraction and gas chromatography/mass spectrometry enabled us to routinely quantify selected VOCs in mainstream cigarette smoke. This technique has similar reproducibility to previous cold trap and impinger collection methods with significantly higher sample throughput and virtually no solvent waste. In this report we demonstrate the method's analytical capabilities by quantitatively analyzing 13 selected VOCs in mainstream cigarette smoke from top-selling domestic brands.     

DNPH-硅胶管采样条件对VOCs检出的影响

采用Sep-Pak DNPH-silica吸附管对室内空气中羰基化合物采样,分析了在不同流速和温度下对各羰基化合物的吸附效率。试验结果表明,两者对采样效率影响明显,采样流量不宜大,环境温度宜略高,且在任何采样条件下,均存在穿透现象。     

Electrostatic separation of volatile organic compounds by ionization

Removal technique of trace volatile organic compounds (VOCs) from air or other gases is of great concern in order to obtain contamination-free indoor air and various process gases for semiconductor manufacturing process. We propose a new technique for separating trace gas components. This technique utilizes preferential ionization and electrical migration of ions. Nitrogen and oxygen gas flow containing toluene vapor is divided into two flows, while the flow is irradiated with alpha-ray from 241Am under a DC electric field. The ionized toluene vapor in one flow electrically migrates into the other flow causing toluene rich and free flows. The separation efficiency of toluene is 50% when 0.5 L/min of inlet nitrogen stream contains 0.15 ppm of toluene at the applied voltage of 250 V. The separation efficiency of toluene increases with the mole fraction of oxygen in the carrier gas. The cation concentration flowing out from the separator is lower than the number of separated toluene molecules by 6 orders of magnitude, but the dependency of toluene separation efficiency on the applied voltage is the same as that of cation separation efficiency. The dependency of separation efficiency on the applied voltage and the gas flow velocity is qualitatively explained by the separation model which accounts for the generation and neutralization of VOC ions in the separator.     

Fate of volatile organic compounds in constructed wastewater treatment wetlands

The fate of volatile organic compounds was evaluated in a wastewater-dependent constructed wetland near Phoenix, AZ, using field measurements and solute transport modeling. Numerically based volatilization rates were determined using inverse modeling techniques and hydraulic parameters established by sodium bromide tracer experiments. Theoretical volatilization rates were calculated from the two-film method incorporating physicochemical properties and environmental conditions. Additional analyses were conducted using graphically determined volatilization rates based on field measurements. Transport (with first-order removal) simulations were performed using a range of volatilization rates and were evaluated with respect to field concentrations. The inverse and two-film reactive transport simulations demonstrated excellent agreement with measured concentrations for 1,4-dichlorobenzene, tetrachloroethene, dichloromethane, and trichloromethane and fair agreement for dibromochloromethane, bromodichloromethane, and toluene. Wetland removal efficiencies from inlet to outlet ranged from 63% to 87% for target compounds.     

微生物挥发性有机化合物及其在线数据库

微生物挥发性有机化合物是微生物代谢产物的重要组成部分,是了解微生物生命活动本质规律的重要窗口,也是提高微生物利用价值的重要物质基础。虽然通过测序方法可以检测病原微生物,但是检测其标志性或指纹挥发物将会更快、更容易。微生物挥发性有机化合物目前被用来作为标记物检测人类疾病、食物腐败和霉菌。细菌和真菌的挥发物信息目前分散在国内外文献中,没有公共的、可更新的数据库可以查询,为满足需要,科学家研制了一套微生物挥发性代谢产物在线数据库,为微生物代谢产物的研究提供参考。本文还举例介绍了微生物挥发性代谢产物检测技术在医学、食品和植物病害防治方面等方面的应用。     

Suppression of sprouting in stored potatoes by volatile organic compounds

A number of readily available volatile compounds have been tested, at concentrations of not greater than 100 μg/l in air, as inhibitors of sprouting of stored potatoes. Some of these compounds were found to be as effective, on a small scale, as the nonyl alcohol used commercially. No compounds of exceptional merit were found.     

Source identification of volatile organic compounds in Houston, Texas

The complexity of the volatile organic compound (VOC) mixture in the Houston area makes studies of the air quality in that area very challenging. In this paper, a novel factor analysis model, where the normal chemical mass balance model was augmented by a parallel equation that accounted for wind speed and direction, temperature, and weekend/weekday effects, was fitted with a multilinear engine (ME) to provide identification and apportionment of the VOC sources at the La Porte Municipal Airport site in Houston during the Texas Air Quality Study (TexAQS) 2000. The analysis determined the profiles and contributions of nine sources and the corresponding wind speed, wind direction, temperature, and weekend factors. The reasonableness of these results not only suggests the high resolving power of the expanded factor analysis model for source apportionment but also provides the novel and effective auxiliary information for more specific source identification. In addition, a new approach to estimate the measurement uncertainty and the details of determining the source number and dealing with missing values are also presented as important parts of the data analysis process. This study demonstrates the feasibility of the expanded model to identify sources in complex VOC systems and extract useful information for locating VOC emitters and controlling their emissions in the Houston area.     

Profiling of volatile compounds of Phyllostachys pubescens shoots in Taiwan

This study examined the influence of heating temperature and duration on volatile aromatic components of spring and winter Phyllostachys pubescens shoots using SPME. Results from GC–MS analyses revealed that the main constituents in both bamboo shoots at ambient temperature include methoxy-phenyl oxime, followed by n-hexanol and 3Z-hexenal, which gives a fresh green aroma. Comparing the different compounds, between spring and winter shoots, revealed that spring bamboo shoots at ambient temperature comprise 12.30% methyl salicylate, which provides protection against insect attack, and 9.71% epi-cedrol; while winter bamboo shoots comprise 17.00% 1-octen-3-ol, which produces a distinct mushroom aroma. After heating at 100 °C for 60 min, a marked increase in relative content of benzyl salicylate (43.30%) and a significant decrease in methyl salicylate content in spring bamboo shoots were observed; while the major compound in winter bamboo shoots was n-heneicosane (78.09%) and the content of specific 1-octen-3-ol significantly decreased.     

食源性腐败菌挥发性有机化合物的研究进展

食源性腐败菌是食品腐败的重要原因, 它可通过初级或次级代谢产生具有异味的挥发性有机化合物(volatile organic compounds, VOCs), 加速食品的腐败进程。腐败菌种类及组成会随食品基质和贮藏条件而改变, 导致产生的VOCs也具有多样性和差异性。随挥发性有机物质收集和检测技术的快速发展, 通过分析腐败菌相关的VOCs成分组成可鉴别食源性腐败菌种类和食物腐败进程。本文对常见腐败菌VOCs的产生途径和种类进行归纳, 并重点探讨了VOCs提取分析技术及在食品腐败研究中的具体应用, 为有效进行腐败菌防控, 提升食品质量和安全提供参考。     

GC/MS法分析烟用接装纸中挥发性有机化合物

建立了顶空-气质联用(HS-GC/MS)法,对烟用接装纸中挥发性有机化合物(VOCs)残留量进行测试.结果表明:(1)该方法检测限为0.001-0.004 mg/mL,回收率为89.35％- 108.96％,相对标准偏差(RSD)＜4％;(2)所有52个被检烟用接装纸榉品均为合格样品,所有样品中均未检出苯、乙苯、二甲苯、乙酸异丙酯、丁酮,YC171-2009《烟用接装纸》标准中规定的5种VOCs成分中只有乙酸正丁酯有个别检出;(3)醇类检出率较高,其中所有样品都有乙醇检出,异丙醇、正丁醇的检出率也比较高;(4)丙二醇甲醚有较高的检出率,且其检出量相对较大.研究结果充分说明,该方法适合于烟用接装纸中VOCs的快速批量检测.     

Modeling effective diffusivity of volatile organic compounds in activated carbon fiber

Volatile organic compounds (VOCs) comprise 67% of total hazardous air pollutants (HAPs) that are emitted by major industrial point sources into the U.S. atmosphere (1). Adsorption by activated carbon fiber (ACF) has been recognized as one of the feasible regenerative control processes to separate and recover VOCs for reuse. Characteristics of VOCs transport in ACFs are required to efficiently design ACF sorption systems. However, extensive resources are spent experimentally obtaining transient sorption data to design adsorption systems. As an alternative, this work develops a new model that predicts effective diffusivities of VOCs into ACFs. The diffusion process is modeled as Knudsen transport into the ACF open pore spaces coupled with activated surface diffusion on the ACF's internal surface area. Temperature and Darken's factors are included in the surface diffusion model to provide corrections for thermodynamic state and deviation from Fick's Law, respectively. Depth of the adsorption potential well is considered as the product of the heat of adsorption of a reference VOC, an adsorption similarity factor, and a surface diffusion energy factor. Introduction of the adsorption similarity factor in the effective diffusivity model is a new concept providing a means to predict effective diffusivity of similar adsorption systems from a reference system. Experimental data from a short length column are used to determine effective diffusivity of acetone in ACF. Results from this diffusivity model are compared to experimental values for the acetone/ACF system to describe the degree of closure between modeled and experimental results.     

Emissions of volatile organic compounds originating from UK livestock agriculture

In this paper we estimate the quantity of non‐methane volatile organic compounds (NMVOCs) emitted from UK livestock. The final estimate is derived from published values and from direct measurements of NMVOC emissions from dairy cattle slurry and laying hen manure. Emission rates of NMVOCs were determined for fresh dairy cattle slurry and laying hen manure using a 40 m³ emissions chamber. Dimethyl sulphides dominated emissions from laying hen manure at 753 ± 263 g m^?3 day^?1. Emissions from dairy cattle slurry were dominated by volatile fatty acids (C₂? C₅, 6.3 ± 3.1 g m^?3 day^?1) and phenols (2.4 ± 1.2 g m^?3 day^?1). Many of these NMVOCs are decomposition products from protein sources from which ammonia is also a by‐product. There is a close association between ammonia and NMVOC production from manure, and on this basis we estimated the annual NMVOC emissions from UK livestock as 165 ± 56 kt for 2002. These emissions compare to those from the larger industrial and transport sectors and exceed the 50–100 kt C year^?1 currently determined as originating from biogenic sources including agriculture. These findings have implications for air quality, and these NMVOCs may affect the cleansing capacity of the troposphere. Copyright © 2004 Society of Chemical Industry     

与环境烟气相关的挥发性有机物的特性

本项研究测定了环境烟气(ETS)中的多种挥发性有机物,在环境实验室中目标化合物的唯一来源就是ETS。实验室中的ETS是由燃吸肯塔基参考卷烟和其他8种市售卷烟产生的。在12轮试验中同时测定了30多种化合物。目标化合物分为3类,即:气相ETS标识物3乙基吡啶(简称3-EP)与烟碱、羰基化合物(包括甲醛)和挥发性有机化合物(简称VOCs)。利用环境实验室研究结果可以确定各种VOCs与3-EP(气相ETS标记物)的特征比率,另外还可以用来估测与ETS相关的VOCs的散发因子。总体说来,本项研究测得的特征比率与以往已经发表的实验室研究数据是一致的,这意味着,"真实"室内环境受多种来源的复杂的混合物影响。本项研究测定的特征比值也可以用于ETS目标化合物的定性和定量分析