Studies on the polymerization of ethyl acrylate. II. Chain transfer studies

Transfer constants for different solvents representing hydrocarbons, halogenated compounds, alcohols, ketones, acids, and esters were determined in the thermal polymerization of ethyl acrylate at 80°C and they are compared with the available data on methyl acrylate and ethyl methacrylate. It was observed from the values of transfer constants that ethyl acrylate radicals are a little more effective than methyl acrylate or ethyl methacrylate in abstracting hydrogen atom from hydrocarbons and alcohols. In acetic and n-butyric acid media, it has been found, by the aid of endgroup analysis, that the derived solvent radicals from transfer reactions are not too efficient to start a new chain.     

Nonsaponifiable lipid components of the pollen of elder (Sambucus nigra L.).

Pollen of the elder (Sambucus nigra L.) was extracted with chloroform-methanol. The extract was separated by column chromatography into the following groups of compounds: hydrocarbons (8.7%). polycyclic aromatic hydrocarbons (0.2%), complex esters (5.2%), triglycerides (18.7%), hydroxy esters (27.9%), free fatty acids and alcohols (16.8%), free sterols (6.8%), and triterpenic alcohols (4.0%). The nonsaponifiable components (hydrocarbons, fatty acids, alcohols, and sterols) were examined in detail using spectroscopic and chromatographic methods (IR spectroscopy, GC, and GC-MS). The identified compounds were characterized by their mass spectra and Kováts retention indices. The double bond positions and their configurations in unsaturated compounds are also reported.     

Ionic Liquid–Liquid Extraction and Supported Liquid Membrane Analysis of Lipophilic Wood Extractives from Dissolving-Grade Pulp

In this study, the extraction of lipophilic wood extractives from dissolving pulp samples using ionic liquid–liquid extraction and a two phase hollow fibre supported liquid membrane was investigated. Ionic liquids are capable of dissolving a range of organic and polymeric compounds and are biodegradable, with a negligible vapour pressure. Pulp samples were dissolved in a suitable amount of molten 1-butyl-3-methylimidazolium chloride to give 5 % cellulose solution. Pure cellulose was regenerated by adding water and filtered off. The ionic liquid-aqueous filtrate was first extracted for lipophilic extractives using liquid–liquid extraction. Then, a two phase hollow fibre supported liquid membrane extraction of lipophilic extractives was performed to extract the derivatized compounds prior to analysis by gas chromatography mass spectrometry. The operational parameters of this sample preparation approach were optimised using sterols and fatty acid methyl esters. The variation of enrichment factors and extraction efficiency with respect to liquid membrane, extraction time, stirring speed and sample pH were observed and used to get the optimal parameters. The approach was used in the analysis of oxygen bleached dissolving pulp samples in which main compounds identified were fatty acids, sterols, fatty alcohols, steroid hydrocarbons and ketones. These compounds were similar to those obtained using molecular solvent extraction method, which indicated the absence of chemical reaction between extractives and ionic liquid used.

     

Analysis of volatile compounds of rosemary honey. Comparison of different extraction techniques

Summary The analysis of the volatile fraction from honey requires the sugar matrix to be separated prior to the analysis by GC-MS. In this study, three extraction techniques, simultaneous extraction-distillation, liquid-liquid extraction and solid-phase extraction, were compared to the extraction of the volatile compounds of a rosemary honey. Analysis of these fractions by gas chromatography—mass spectrometry enabled the tentative identification of up to 122 volatile compounds (alcohols, ketones, aldehydes, acids, esters, terpenes, hydrocarbons, phenol, furan and pyran compounds). SDE extracts were rich in terpenes and esters, while the other two techniques avoided the formation of artefacts due to heating the sample.     

Comparative study of the whisky aroma profile based on headspace solid phase microextraction using different fibre coatings

A dynamic headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled to ion trap mass spectrometry (GC-(IT)MS) method was developed and applied for the qualitative determination of the volatile compounds present in commercial whisky samples which alcoholic content was previously adjusted to 13% (v/v). Headspace SPME experimental conditions, such as fibre coating, extraction temperature and extraction time, were optimized in order to improve the extraction process. Five different SPME fibres were used in this study, namely, poly(dimethylsiloxane) (PDMS), poly(acrylate) (PA), Carboxen-poly(dimethylsiloxane) (CAR/PDMS), Carbowax-divinylbenzene (CW/DVB) and Carboxen-poly(dimethylsiloxane)-divinylbenzene (CAR/PDMS/DVB). The best results were obtained using a 75 microm CAR/PDMS fibre during headspace extraction at 40 degrees C with stirring at 750 rpm for 60 min, after saturating the samples with salt. The optimised methodology was then applied to investigate the volatile composition profile of three Scotch whisky samples--Black Label, Ballantines and Highland Clan. Approximately seventy volatile compounds were identified in the these samples, pertaining at several chemical groups, mainly fatty acids ethyl esters, higher alcohols, fatty acids, carbonyl compounds, monoterpenols, C13 norisoprenoids and some volatile phenols. The ethyl esters form an essential group of aroma components in whisky, to which they confer a pleasant aroma, with "fruity" odours. Qualitatively, the isoamyl acetate, with "banana" aroma, was the most interesting. Quantitatively, significant components are ethyl esters of caprilic, capric and lauric acids. The highest concentration of fatty acids, were observed for caprilic and capric acids. From the higher alcohols the fusel oils (3-methylbutan-1-ol and 2.phenyletanol) are the most important ones.     

Quantification approach for assessment of sparkling wine volatiles from different soils, ripening stages, and varieties by stir bar sorptive extraction with liquid desorption

Stir bar sorptive extraction with liquid desorption followed by large volume injection coupled to gas chromatography-quadrupole mass spectrometry (SBSE-LD/LVI-GC-qMS) was applied for the quantification of varietal and fermentative volatiles in sparkling wines. The analytical data were performed by using suitable standards of monoterpene hydrocarbons (α-pinene), monoterpenols (linalool), sesquiterpenoids (E,E-farnesol, Z-nerolidol, and guaiazulene), C₁₃ norisoprenoids (β-ionone), aliphatic and aromatic alcohols (hexanol and 2-phenylethanol), and esters (hexyl acetate and ethyl decanoate) as model compounds. The wine volatiles were quantified using the structurally related standards. The methodology showed good linearity over the concentration range tested, with correlation coefficients ranging from 0.950 to 0.997, and a reproducibility of 9-18%. The SBSE-LD/LVI-GC-qMS methodology allowed, in a single run, the quantification of 71 wine volatiles that can be quantified accurately at levels lower than their respective olfactory thresholds. This methodology was used for assessment of sparkling wine volatiles from different soils, ripening stages, and varieties. The variety and soil influenced significantly the volatile composition of sparkling wines; lower effect was observed for the ripening stage of grapes picked up one week before or after the maturity state.     

Synthesis,characterization, and thermal properties of new flavor compounds

Synthesis, characterization, and thermal properties of new, flavor, long chain esters were presented. The new compounds were obtained in the catalytic esterification process of a stoichiometric ratio of trans-3,7-dimethyl-2,6-octadien-1-ol, succinic anhydride, and aliphatic chain diol. As diols ethylene glycol, 1,4-buthylene glycol, 1,5-pentylene glycol, and 1,6-hexylene glycol were applied. The spectroscopic analyses completely confirmed that the applied synthesis conditions allowed obtaining the new compounds with high yield and purity. Their thermal properties were studied in inert and oxidative atmospheres. The esters were less thermally stable in inert (IDT 186–195 °C) than in oxidative (IDT 210–228 °C) atmosphere. Two, non-completely divided decomposition steps were visible during their pyrolysis. In contrast, the new, long chain compounds decompose in three major steps in air. The analyses of the volatile products emitted during their pyrolysis indicated on the asymmetrical disrupt of their bonds. The formation of acyclic and alicyclic monoterpene hydrocarbons, succinic anhydride, diols, alcohols, alkenes, and water was observed. It indicated mainly on the β-elimination reactions during their pyrolysis. Also, β-elimination reactions of esters are mainly expected in air. Initially, it resulted in the formation of acyclic and alicyclic monoterpene hydrocarbons, hydroxyl compounds (diols, alcohols), and its β-elimination products: aldehydes, alkenes, and water. However, the presence of oxygen in the medium causes the partial decarboxylation and oxygenation of aldehydes and thus the formation of alkenes and carbon dioxide. In addition, the beginning of evaporation of succinic anhydride was detected at T _max1. At T _max2 the evaporation of succinic anhydride, their partial decarboxylation to CO₂, the small amounts of diols, alcohols, and aldehyde fragments were indicated. Finally, succinic anhydride, water, and carbon dioxide were only observed during decomposition of studied esters in air.     

水稻秸秆石油醚和乙醇萃取物的组成分析

用石油醚和乙醇在索式萃取器中对水稻秸秆进行了萃取,萃取物用傅里叶转换红外光谱仪（FTIR）和气相色谱 质谱联用仪（GC/MS）分析。 结果表明,乙醇和石油醚的萃取率分别为8%和6%。 萃取物中共检测到40种物质,主要分为醇酚（APs）、醛、酮、酸、酯、烃（HCs）及含氮化合物（ONs）7种类别。 其中,石油醚萃取物中酯、HCs和APs 3类物质含量较高,总的相对含量为91.7%;乙醇萃取物中HCs、酸、酯及APs含量较高,总的相对含量为83.9%。 该研究在开发稻秆的高附加值利用方面具有重要的基础理论意义。     

索式法提取芫荽茎叶精油的化学组成及其抗菌活性

以乙醚为溶剂,采用索式萃取法萃取新鲜香菜,以0.252%的产率获得了芳香精油.利用GC-MS分析仪对精油进行了分析,检测出60个成分,解析了占精油94.200%的41个成分,其中,酯类化合物占57.755%,烷烃类化合物11.300%,醛类化合物16.168%,芳香族化合物8.077%.与水蒸汽蒸馏法获得的精油以及香菜原汁的抗菌作用进行了比较,结果显示水蒸汽蒸馏法和索式法提取的精油对大肠杆菌,白葡萄球菌具有很强的抑制作用,但是,香菜精油和原汁对米曲霉、黑曲霉完全没有抑菌作用.     

Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry of monoterpenoids as a powerful tool for grape origin traceability

The establishment of the monoterpenoid profile of Vitis vinifera L. cv. 'Fern?o-Pires' white grape was achieved by headspace solid-phase microextraction coupled with comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-ToF-MS). The plot of the first dimension versus the second dimension retention times using the m/z 93, 121, and 136 was used. The grapes were found to contain 56 monoterpenoids identified by GCxGC-ToF-MS. From these, 20 were reported for the first time in grapes. According to their chemical structure, the compounds were organized in different groups: monoterpene hydrocarbons and monoterpene oxygen-containing compounds, this later divided in oxides, alcohols (monoterpenols and monoterpendiols), aldehydes, esters, and ketones. A database composed by the retention indices of monoterpenoids calculated in the bi-dimensional column set was created, representing a developmental step in monoterpenoid analysis using a GCxGC system. Remarkable results were also obtained in terms of compound classification based on the organized structure of the peaks of structurally related compounds in the GCxGC contour plot. This information represents a valuable approach for future studies, as the ordered-structure principle can considerably help the establishment of the composition of samples. This study proposes a methodology and provides data that can be applied to determine the monoterpenoid profile of grapes, and its extension to the analysis of musts, and wines. As monoterpenoids are secondary metabolites whose synthesis is encoded by variety-related genes, the terpenoid profile may be used as a way to trace its varietal origin.     

Volatile organic compounds of Angelica gigas Nakai, Korean medicinal herb

The study was performed to find out the profile of volatile flavor components from the aromatic medicinal plant, Angelica gigas Nakai. The volatile organic compounds of A. gigas Nakai were extracted by simultaneous steam distillation and extraction (SDE) method, and identified by gas chromatograph/mass spectrometric (GC/MS) analysis. A total of 116 compounds, including 40 hydrocarbons, 37 alcohols, 15 esters, 12 aldehydes, 7 ketones, and 5 miscellaneous were identified and quantified. Among them, 75 volatile organic compounds were detected which make up 90.52% of total volatile content. alpha-Pinene was detected as the prime volatile component which accounted for 30.89% of total volatile content and 2,4,6-trimethyl heptane, camphene, alpha-limonene, beta-eudesmol, vervenol, alpha-murrolene, and sphatulenol were detected as the major components of A. gigas Nakai.     

顶空固相微萃取-气相色谱-质谱法测定小米黄酒风味成分

为全面了解小米黄酒风味成分的构成和气味特征,优化了85μm聚丙烯酸酯(PA)、100μm聚二甲基硅氧烷(PDMS)、75μm碳分子筛(CAR)/PDMS、50/30μm二乙烯基苯(DVB)/CAR/PDMS萃取头提取小米黄酒风味成分的条件,采用顶空固相微萃取(headspace solid phase microextraction,HS-SPME)-气相色谱-质谱法(GC-MS)对风味成分进行定性、定量分析,并计算气味活性值(odor active value,OAV),同时利用OAV分析风味成分的气味特征和气味强度。结果显示:不同萃取头的最优萃取条件为样品量8 mL、萃取时间40 min、萃取温度60℃、NaCl添加量1.5 g。小米黄酒风味成分由醇、酯、含苯化合物、烃、酸、醛、酮、烯、酚和杂环类化合物构成,醇为主要风味成分。通过OAV确定了苯乙醇、苯乙烯、2-甲基萘、1-甲基萘、苯甲醛、苯乙醛、2-甲氧基-苯酚为小米黄酒气味特征成分,苯基乙醇、苯乙醛对气味贡献最大。PA和PDMS萃取头分别对极性和非极性化合物具有较好的吸附效果,CAR/PDMS和DVB/CAR/PDMS萃取头对中等极性化合物具有较好的吸附效果。该研究全面了解了小米黄酒风味成分的构成,为其产品开发及品质控制提供理论了依据。     

Identification of volatile components of liverwort (Porella cordaeana) extracts using GC/MS-SPME and their antimicrobial activity

Chemical constituents of liverwort (Porella cordaeana) extracts have been identified using solid-phase microextraction-gas chromatography mass spectrometry (SPME-GC/MS). The methanol, ethanol and ethyl acetate extracts were rich in terpenoids such as sesquiterpene hydrocarbons (53.12%, 51.68%, 23.16%), and monoterpene hydrocarbons (22.83%, 18.90%, 23.36%), respectively. The dominant compounds in the extracts were β-phellandrene (15.54%, 13.66%, 12.10%) and β-caryophyllene (10.72%, 8.29%, 7.79%, respectively). The antimicrobial activity of the extracts was evaluated against eleven food microorganisms using the microdilution and disc diffusion methods. The minimum inhibitory concentration (MIC) varied from 0.50 to 2.00 mg/mL for yeast strains (Saccharomyces cerevisiae 635, Zygosacharomyces bailii 45, Aerobasidium pullulans L6F, Pichia membranaefaciens OC 71, Pichia membranaefaciens OC 70, Pichia anomala CBS 5759, Pichia anomala DBVPG 3003 and Yarrowia lipolytica RO13), and from 1.00 to 3.00 mg/mL for bacterial strains (Salmonella enteritidis 155, Escherichia coli 555 and Listeria monocytogenes 56Ly). Methanol extract showed better activity in comparison with ethanol and ethyl acetate extracts. High percentages of monoterpene and sesquiterpene hydrocarbons could be responsible for the better antimicrobial activity.     

Characterization of Ayran Aroma Active Compounds by Solvent-Assisted Flavor Evaporation (SAFE) with Gas Chromatography–Mass Spectrometry–Olfactometry (GC–MS–O) and Aroma Extract Dilution Analysis (AEDA)

The aroma compounds of ayran were isolated using solvent-assisted flavor evaporation (SAFE) resulting in a more representative extract of ayran odor compared to liquid–liquid extraction (LLE), solid-phase extraction (SPE), and simultaneous distillation–extraction (SDE). The aromatic extract was subjected to sensory analysis and identified and quantified by gas chromatography–mass spectrometry (GC–MS). A total of 19 volatile compounds were detected that included alcohols, aldehyde, acids, esters, ketones, and terpenes. However, the compounds present at the highest concentrations were ethyl lactate, ethanol, 2,3-butanediol, acetoin, and acetic acid. The key odorants for the ayran drinks were detected using aroma extract dilution analysis (AEDA) and GC–MS–olfactometry (GC–MS–O). A total of 14 aroma-active compounds were determined for the first time. The flavor dilution (FD) factors ranged between 4 and 512 while their odor activity values (OAVs) were from 1.35 to 1126.99. Ethyl lactate (FD of 512 whey/creamy), 2-methylbutanal (FD of 512, fruity), acetoin (FD of 256, buttery creamy), and butanoic acid (FD of 256, cheesy-sweet) were the strongest aroma-active components of the Ayran drink.     

大气光化学反应研究（Ⅱ）—二氧化硫与异戊烷的光化学反应

研究了SO_2与异戊烷在无氧和有氧体系中的光化学反应,用GC和GC-MS法确证了部分气、液相产物,包括醇、醛、酮、酯和烃类及含硫有机物,探讨了影响光化学反应的因素和反应机理.     

鸽子粪挥发性成分的毛细管气相色谱分析

利用同时蒸馏萃取法（ＳＤＥ）提取了有治疗痔疮效果的鸽子粪中的挥发性成分。用毛细管ＧＣ／ＭＳ／ＤＳ联用法分离鉴定了４７种组分,占总峰面积的７１．５９％,再用保留指数和标样进一步确证了其中３９种化合物,占总峰面积的５７．１５％,其中含量较高的组分是十六碳酸（９．０３％）、乙酸乙酯（６．８５％）、乙醇（４．０３％）、１－乙氧基－２－甲基丙烷（３．８７％）。从化合物的种类看,主要为醇类（４个）、醛类（１１个）、酮类（４个）、酸类（８个）、酯类（５个）和酚类（２个）,它们共占总峰面积的４３．６８％。     

Preliminary Characterization of the Composition and Phenolic Fragmentation of Olive Byproducts by Gas Chromatography–Mass Spectrometry and High-Performance Liquid Chromatography–Tandem Mass Spectrometry

Olive waste is a potential resource due to its rich variety of biologically active compounds. To investigate chemical components of olive waste, the selected samples were extracted using ultrasound assisted enzyme hydrolysis and petroleum ether, ethyl acetate and n-butyl alcohol were used to obtain a series of solvent extracts. Gas chromatography–mass spectrometry analysis showed hydrocarbons, esters, acids, alcohols, and ketones present in the extracts. Some fatty acids were considered to be predominant; it is noteworthy that phenolic compounds were detected in the ethyl acetate extract fraction. Furthermore, the primary phenolic compounds were also determined by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry. The possible fragmentation patterns have been proposed in positive and negative ion modes; the main fragment ions were observed from the loss of methyl, hydroxyl, or carboxyl groups. The compounds showed different fragmentation ions types in both positive and negative ionization modes and gave structural information on the main phenolic compounds in olive waste. The results of this study may be used to identify valuable active compounds and guide commercial applications of olive waste.     

青蒿挥发性化学成分分析

用同时蒸馏－萃取装置（ＳＤＥ）提取了青蒿的挥发性物质,用ＧＣ－ＭＳ法分析鉴定出５０种化合物,其中主要成分为醛类（１８．１６％）、酮类（８．２４％）、醇类（１７．３６％）、酯类（１１．０２％）、酸类（７．３１％）、烃及萜类（２５．５８％）、杂环类（１０．３８％）,占总检出量的９８．０５％。     

Relationship between Volatile Composition and Bioactive Potential of Vegetables and Fruits of Regular Consumption—An Integrative Approach

In recent years, there has been a growing interest in studying and exploring the potential health benefits of foods, mainly from vegetables and fruits from regular intake. The presence of secondary metabolites, namely polyphenols, carotenoids and terpenes, in certain food matrices seems to contribute to their functional properties, expressed through an increased prevention in the development of certain chronic diseases, namely coronary heart diseases, neurodegenerative diseases, cancer and diabetes. However, some foods’ volatile secondary metabolites also present important bioactive properties, although this is a poorly scientifically explored field. In this context, and in order to explore the potential bioactivity of volatile metabolites in different vegetables and fruits from regular consumption, the volatile composition was established using a green extraction technique, solid phase microextraction in headspace mode (HS-SPME), combined with gas chromatography tandem mass spectrometry (GC-MS). A total of 320 volatile metabolites, comprising 51 terpenic compounds, 45 organosulfur compounds, 31 aldehydes, 37 esters, 29 ketones, 28 alcohols, 23 furanic compounds, 22 hydrocarbons, 19 benzene compounds, 13 nitrogenous compounds, 9 carboxylic acids, 7 ethers, 4 halogenated compounds and 3 naphthalene derivatives, were positively identified. Each investigated fruit and vegetable showed a specific volatile metabolomic profile. The obtained results revealed that terpenic compounds, to which are associated antimicrobial, antioxidant, and anticancer activities, are the most predominant chemical family in beetroot (61%), orange carrot (58%) and white carrot (61%), while organosulfur compounds (antiviral activity) are dominant in onion, garlic and watercress. Broccoli and spinach are essentially constituted by alcohols and aldehydes (enzyme-inhibition and antimicrobial properties), while fruits from the Solanaceae family are characterized by esters in tamarillo and aldehydes in tomato.     

Mono- and sesquiterpenoids of the oleoresin ofPinus koraiensis andP. pumila. crystal structure of 1β,4αH,7αH,10βH-Guaiane-5α,14-diol

The composition of the mono- and sesquiterpenoids of the oleoresin of two species of conifers of thePinaceae family has been studied. In the oleoresin ofPinus koraiensis Sieb. et Zucc. 10 oxidized monoterpenoids, 18 sesquiterpene hydrocarbons, and six sesquiterpene alcohols have been identified. In theoleoresin ofPinus pumila (Pall.) Rg1. 10 monoterpene hydrocarbons, six oxidized monoterpenoids, 14 sesquiterpene hydrocarbons, and four sesquiterpene alcohols have been found. The structure of 1β,4αH,7αH,10βH-guaiane-5α,14-diol, one of the hydroboration-oxidation products of an unidentified sesquiterpene alcohol isolated from both oleoresins, has been determined by x-ray structural analysis.