新型潜香类化合物N-(2,3-吡嗪二甲酰基)-丙氨酸甲酯热裂解气相色谱-质谱分析

采用在线热裂解-气相色谱-质谱联用技术(Py-GC-MS)分析了潜香吡嗪类化合物N-(2,3-吡嗪二甲酰基)-丙氨酸甲酯的热裂解行为。首先通过对2,3-吡嗪二羧酸酰胺化反应合成了新型目标化合物N-(2,3-吡嗪二甲酰基)-丙氨酸甲酯,其结构经X射线单晶衍射(XRD),1H NMR,13C NMR,IR和HR-MS证实,然后在空气氛围中,对目标化合物分别在300,600,900℃下进行热裂解,并通过GC-MS对其挥发性热裂解产物进行定性和半定量分析。结果表明:1裂解形成了包括具有香味特征的吡嗪类、大茴香醇和大茴香醛在内的裂解产物共48种。不同温度下挥发性热裂解产物的类型和相对含量不同,300℃和600℃时相对含量最高的均为乙酸,而900℃时相对含量最高的为吡嗪,且与300℃和600℃裂解条件相比所形成的吡嗪类衍生物种类较多,相对含量较高。2在具有香味特征的裂解产物中,大茴香醇的相对含量随温度升高而升高,而大茴香醛和苯甲醛的相对含量则呈现随着温度升高而降低的趋势。基于目标化合物的热裂解产物的定性及定量变化情况,初步探讨了该物质可能的裂解机理。     

新型潜香化合物3,6-二甲基-2,5-吡嗪二甲酸二薄荷醇酯的热裂解产物

为开发新型高温释放型烟用香料,以2,3,5,6-四甲基吡嗪和薄荷醇为原料,经过酯化反应制备了3,6-二甲基-2,5-吡嗪二甲酸二薄荷醇酯(DPAME).采用在线热裂解-气相色谱-质谱联用技术(Py-GC-MS)在空气氛围和不同的温度(300、600和900 ℃)下,对DPAME进行热裂解研究,裂解产物经GC-MS进行了定性和半定量分析.结果表明,DPAME在300 ℃下裂解产生了多种有致香效果的醛类、薄荷烯和薄荷醇等;在600 ℃和900 ℃下裂解产生了烯烃类、烷基吡嗪、薄荷醇和薄荷烯等香味物质,并且吡嗪类的种类和相对含量在这两个温度下明显增加.结合DPAME的热裂解产物分析和卷烟感官评吸结果,初步推测了其可能的裂解机理.采用该方法可以方便、快速地分离鉴定物质的热裂解产物,为该物质在烟草中的加香应用提供理论依据.     

热裂解-气相色谱-质谱法分析烟用咖啡颗粒热裂解特性

利用热裂解-气相色谱-质谱联用分析烟用咖啡颗粒的热裂解特性。分别于150、200、250、300、350℃对烟用咖啡颗粒进行热裂解分析，同时针对不同水分含量和粒径的咖啡颗粒在同一温度下进行热裂解成分分析。结果显示，随着温度的升高，热裂解产物逐渐增多，释放物质的种类逐渐也逐渐增多，在250℃时咖啡颗粒生成关键致香成分占比较高。不同水分含量和粒径的咖啡颗粒在250℃裂解时，水分越高，裂解产物中烟碱含量占比越高，烟气越充足；粒径越小，裂解产物中咖啡因和烟碱的总量越大，香气质量也越高。该试验为咖啡颗粒在卷烟中应用时的温度设计和香气品质改善提供理论依据。     

香料成分的结构与高温裂解产生芳香物质含量的关系研究

应用在线热裂解/气相色谱-质谱(PY/GC-MS)研究了紫苏葶、β-紫罗兰酮、香紫苏内酯、异丁香酚、苯甲醛、2-乙酰基吡嗪、2-乙酰基噻唑、3-乙酰基吡啶、山楂酊、树兰净油在氦气氛围中分别于300、600、800℃下的裂解产物,通过对裂解产物中芳香烃类化合物的分析,讨论了裂解温度和香料组分化学结构对芳香族物质产生量的影响,并以有机结构理论总结了香料成分的结构与高温裂解产生芳烃物质含量的关系。研究结果表明:β-紫罗兰酮、香紫苏内酯、异丁香酚、树兰净油等在800℃时均裂解生成芳香烃类化合物(苯系物、茚系物和萘系物),其中裂解物中芳香烃类物质含量最高者为β-紫罗兰酮,达到16.290%,树兰净油为5.376%;而2-乙酰基吡嗪、2-乙酰基噻唑、3-乙酰基吡啶的裂解产物中未检测到上述芳香烃类物质,香料成分的结构是高温裂解产生芳烃物质的重要因素;随着裂解温度的升高,裂解产物中芳香烃类化合物的含量呈上升趋势;其中2-乙酰基吡嗪、2-乙酰基噻唑和3-乙酰基吡啶适宜用作卷烟香料。     

热裂解气相色谱-质谱法联用测定卷烟中烯烃类化合物释放量

卷烟样品在不同温度(400,600,800,1 000,1 200℃)下裂解后,用气相色谱-质谱法测定卷烟中烯烃类化合物的释放量。结果表明:有害性烯烃类化合物的释放量随热裂解温度的升高而增多;当热裂解温度为600℃时,烯烃类香味物质的累计释放量达到最大值。因此,当卷烟燃烧温度在600℃附近,烟气中有害产物的释放量将大幅减少,并保持清香香气的丰满度。     

裂解气相色谱-质谱法对黄芩浸膏热裂解产物分析

采用热失重分析法(TGA)和在线热裂解气相色谱-质谱法(Py-GC-MS)研究了黄芩浸膏热裂解性质。在氦气氛围中,将黄芩浸膏分别在300,450,600,750,900℃下进行热裂解,并以气相色谱-质谱法对其裂解产物进行定性和半定量分析,并用黄芩浸膏进行了卷烟加香试验。结果表明:①在热失重曲线图中不能较明显地看出黄芩浸膏的较大失重点;②黄芩浸膏在上述温度下检测到的主要挥发性热裂解产物分别为12,18,28,42,40种;③600℃以下,黄芩浸膏热裂解产物主要是醛类、酮类、酯类和呋喃类物质;有害物质的量随着温度的升高而提高;900℃时,则主要为苯、甲苯、萘等有害成分;④黄芩浸膏具有提高卷烟香气质量、改善余味、柔和烟气的作用。     

热裂解气相色谱-质谱法对聚四氟乙烯涂层的热裂解产物分析

提出了热裂解气相色谱-质谱法(Py-GC-MS)研究聚四氟乙烯涂层的热裂解性质。采用管炉型热裂解装置和不锈钢毛细管柱,根据样品的复杂程度进行分阶段释放气体分析,得到聚四氟乙烯涂层不同热裂解阶段的释放气体色谱图。结果表明:聚四氟乙烯涂层在100～300℃热裂解温度下检测到的热裂解产物为1,4-二甲基-2,5-二乙基苯、异丙氧基苯胺、双酚A;在300～380℃热裂解温度下检测到的热裂解产物为苯乙烯、α-甲基苯乙烯、4,4′-二甲基苯胺;在380～460℃热裂解温度下检测到的热裂解产物为苯酚、苯胺、对氨基甲苯、二苯醚;在460～600℃热裂解温度下检测到的热裂解产物为四氟乙烯单体。     

在线热裂解/气相色谱-质谱分析3-吡啶甲酸茴香酯的热裂解产物

采用在线热裂解/气相色谱-质谱(Py/GC-MS)联用技术对3-吡啶甲酸茴香酯进行热裂解分析。通过酰氯化和酯化反应合成了新型目标化合物3-吡啶甲酸茴香酯,其分子式为C14H14NO3。目标化合物的结构经核磁氢谱(1H NMR)、核磁碳谱(13C NMR)、红外光谱(IR)和高分辨质谱(HRMS)进行确证,并通过热重-微热重-差示扫描量热(TG-DTG-DSC)分析方法对目标化合物的热稳定性进行分析。在空气氛围中,将目标化合物分别于300,600,900℃下进行热裂解,并通过气相色谱-质谱法对其挥发性热裂解产物进行定性和半定量分析。研究显示:目标化合物共经历了两次失重过程。第一次失重在129.9~158.9℃之间,失重2.3%;第二次失重在158.9~274.9℃之间,失重达90.1%,230.1℃时失重率最大。热裂解共产生44种产物,包括具有香味特征的大茴香醛、对甲基苯酚、松油醇、D-香茅醇、大茴香醚和茴香醚等化合物。其中裂解温度对裂解产物的种类和相对含量具有明显影响。300℃时α-二去氢菖蒲烯的相对含量最高,600,900℃时,相对含量最高的分别是大茴香醛和对甲基苯酚。苯甲醛、茴香醚和大茴香醚的相对含量随着温度的升高呈先增加后降低趋势;而对甲基苯酚含量则随着温度的升高而增加。根据主要裂解产物及其相对含量的变化,对目标化合物的裂解机理进行了初步探讨。     

裂解气相色谱-质谱法研究壬酸香草酰胺的热裂解

采用在线热裂解/气相色谱-质谱联用技术(Py/GC-MS)对壬酸香草酰胺(PAVA)的热裂解行为进行了研究,在氦气氛围中考察了不同裂解温度和裂解时间对PAVA裂解的影响,通过GC-MS对裂解产物进行定性和半定量分析。结果表明,随着裂解温度的升高,PAVA裂解率快速提高,裂解产物也进一步增多,当裂解温度达到700℃以上时,可裂解出壬酰胺、2-甲氧基-4-甲基苯酚、1-己烯、壬基腈、壬醛等14种产物。同一温度下随着裂解时间的延长,PAVA的裂解率逐步升高,裂解产物发生了进一步的裂解。根据热裂解产物及主要裂解产物的含量变化,初步推断了PAVA的裂解规律。     

裂解气相色谱-质谱联用法对桔梗浸膏的热裂解产物分析

采用在线热裂解气相色谱-质谱法(Py-GC-MS)法研究了桔梗浸膏热裂解性质.在氦气氛围中,将桔梗浸膏分别在不同温度下进行热裂解,并以气相色谱-质谱法(GC-MS)对其裂解产物进行定性和半定量分析,并用桔梗浸膏进行了卷烟加香试验.结果表明:桔梗浸膏在300,450,600,750,900℃裂解温度下检测到的挥发性热裂解产物分别达20种、33种、48种、46种和46种;桔梗浸膏具有改善和修饰卷烟吸味、丰满烟气、减轻刺激性的作用.桔梗浸膏添加到卷烟中能明显的提高卷烟抽吸品质.     

Effect of different temperatures on the properties of pyrolysis products of Parthenium hysterophorus

This research encompasses the use of noxious weed Parthenium hysterophorus as feedstock for pyrolysis carried out at varying temperatures of 300, 450 and 600°C. Temperature significantly affected the yield and properties of the pyrolysis products including char, syngas and bio-oil. Biochar yield decreased from 61% to 37% from 300 °C to 600 °C, whereas yield of gas and oil increased with increasing temperature. The pyrolysis products were physico-chemically characterized. In biochar, pH, conductivity, fixed carbon, ash content, bulk density and specific surface area of the biochar increased whereas cation exchange capacity, calorific value, volatile matter, hydrogen, nitrogen and oxygen content decreased with increasing temperature. Thermogravimetric analysis showed that the biochar prepared at higher temperature was more stable. Gas Chromatography-Mass Spectrometry analysis of biochar indicated the presence of alkanes, alkenes, nitriles, fatty acids, esters, amides and aromatic compounds. Number of compounds decreased with increasing temperature, but aromatic compounds increased with increasing temperature. Scanning electron micrographs of biochar prepared at different temperatures indicated micropore formation at lower temperature while increase in the size of pores and disorganization of vessels occurred at increasing temperature. The chemical composition was found to be richer at lower pyrolysis temperature. GC–MS analysis of the bio-oil indicated the presence of phenols, ketones, acids, alkanes, alkenes, nitrogenated compounds, heterocyclics and benzene derivatives.     

Flash Pyrolysis and Kinetic Parameters of Decomposition of Oil Shales

Flash pyrolysis of oil shales, distribution of the organic matter in the volatile products, solidresidue at various pyrolysis temperatures were studied. The concentrations of aliphatic hydrocarbons andnaphthenes + arenes in the volatile products were determined.     

裂解气相色谱-质谱联用技术研究黑香豆酊的热裂解行为

采用裂解气相色谱-质谱联用法研究了香精黑香豆酊在不同温度下的裂解行为,分析了黑香豆酊在不同温度下的热裂解产物,并用归一化法进行了定量。结果发现黑香豆酊在不同温度下表现出不同的转移行为,其热解产物和机理也各不相同。检索到苯并呋喃、香豆素和肉桂醛等16种致香物质。随着温度的升高,裂解产物中逐渐产生出有害物质。初步探讨了香豆素可能的裂解机理,为香味物质在卷烟燃烧过程的转化行为提供了例证。     

The Maillard Reaction as Source of Meat Flavor Compounds in Dry Cured Meat Model Systems under Mild Temperature Conditions

Flavor is amongst the major personal satisfaction indicators for meat products. The aroma of dry cured meat products is generated under specific conditions such as long ripening periods and mild temperatures. In these conditions, the contribution of Maillard reactions to the generation of the dry cured flavor is unknown. The main purpose of this study was to examine mild curing conditions such as temperature, pH and a_w for the generation of volatile compounds responsible for the cured meat aroma in model systems simulating dry fermented sausages. The different conditions were tested in model systems resembling dry fermented sausages at different stages of production. Three conditions of model system, labeled initial (I), 1st drying (1D) and 2nd drying (2D) and containing different concentrations of amino acid and curing additives, as well as different pH and a_w values, were incubated at different temperatures. Changes in the profile of the volatile compounds were investigated by solid phase microextraction and gas chromatography mass spectrometry (SPME-GS-MS) as well as the amino acid content. Seventeen volatile compounds were identified and quantified in the model systems. A significant production of branched chain volatile compounds, sulfur, furans, pyrazines and heterocyclic volatile compounds were detected in the model systems. At the drying stages, temperature was the main factor affecting volatile production, followed by amino acid concentration and a_w. This research demonstrates that at the mild curing conditions used to produce dry cured meat product volatile compounds are generated via the Maillard reaction from free amino acids. Moreover, in these conditions a_w plays an important role promoting formation of flavor compounds.     

Utilization of thermodesorption coupled to GC-MS to study stability of different wood species to thermodegradation

Thermodesorption coupled to gas chromatography coupled to mass spectroscopy (TD-GC-MS) has been investigated to identify volatile degradation products generated during wood heat treatment by mild pyrolysis. For this purpose, wood samples of different softwood and hardwood species have been heat treated under nitrogen for different temperatures comprised between 180 and 230 °C during 15 min in the glass thermal desorption tube of the thermodesorber and the volatile wood degradation products trapped. The trapped products were then thermodesorbed and analysed by GC-MS. Chromatograms of the different samples indicated the formation of different products resulting from degradation of lignin and hemicelluloses. Hardwoods were shown to be more sensitive to thermodegradation than softwoods, for which degradation products appear at slightly higher temperature. The important formation of acetic acid is concomitant with the formation of most of degradation products and at the origin of the difference of reactivity observed between softwoods and hardwoods.     

On the interaction of HBT with pulp lignin during mediated laccase delignification—a study using fractionated pyrolysis-GC/MS

An analytical method using fractionated pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was developed and applied for characterizing the type of interaction between 1-hydroxybenzotriazole (HBT)-mediator and pulp lignin in laccase delignification of pulp. In fractionated pyrolysis, the sample is pyrolyzed at progressively increasing temperatures in order to study particular fractions of the sample and to minimize secondary pyrolysis effects. This makes it possible to determine whether a certain pyrolysis product originates from one chemical moiety or different chemical moieties in one molecule. In the present method, samples were fractionated by thermal desorption at 200 °C followed by pyrolysis at progressively increasing temperatures from 320 to 800 °C. The products formed in each fraction were separated in a capillary GC column and detected and identified using MS. The type of interaction between HBT and pulp lignin was studied by following the formation of nitrogen-containing products during fractionated pyrolysis of a residual lignin isolated from laccase/HBT-treated oxygen-delignified softwood kraft pulp. This residual lignin was found to contain approximately 2% HBT residue. Most (87%) of this residue was covalently linked to the residual lignin. The results also strongly suggest that the HBT residue is present in two chemically different forms.     

生物质焦制备条件对其燃烧反应特性的影响

在热重分析仪上，研究了生物质焦的制备条件对其燃烧反应特性的影响。生物质焦由闪速裂解技术制得，裂解温度为 748 K、773 K和823 K；原料含水质量分数为0、7.0%和11.3%。研究发现，生物质焦中挥发性物质的质量分数和H/C质量比随裂解温度的增加而降低，其燃烧反应性随裂解温度的增加而降低；与高裂解温度条件下制得的生物质焦相比，低裂解温度条件下制得的生物质焦具有较高的反应活化能和对燃烧温度更敏感。原料含水量对生物质焦的燃烧反应特性影响很小；但对高裂解温度条件下制得的生物质焦中的挥发性组分含量有较大的影响。简化的生物质焦本征燃烧反应幂函数动力学模型可以很好地描述其燃烧行为。     

Thermal degradation of α-pinene using a Py–GC/MS

Mediterranean forest fires may be accelerated, partly due to biogenic volatile organic compounds produced by vegetation, mainly monoterpenes largely represented by α-pinene. To model the propagation of biomass combustion, it is necessary to study the flammability of the produced gas mixture, and thus, necessary to identify the emitted volatile compounds. However, thermal degradation of monoterpenes is rarely experimented above 300 °C, whereas forest fires reach higher temperatures. Thus, in this work, we experimented a 2-min pyrolysis of α-pinene at temperatures from 300 to 800 °C using a Py–GC/MS device. Less than 1% of pyrolysis products were detected at 300 and 400 °C. The pyrolysis products increased then from 14 compounds at 500 °C to 31 compounds at 800 °C. Degradation of α-pinene started with its isomerization at 500 °C. At 800 °C, alkenes detected increased as well as aromatics produced through the Diels–Alder mechanism. These results are consistent with the literature on thermal degradation of α- and β-pinene presented in our article.

     

在线裂解气相色谱/质谱联用法研究4-氧代-β-大马酮的热裂解行为

用在线裂解气相色谱/质谱法(PyGC/MS)研究了4-氧代-β-大马酮的热裂解行为。在氦气氛围中,将4-氧代-β-大马酮分别在350,450,550,650,700和750 ℃下进行热裂解,并以GC/MS对其裂解产物进行定性和半定量分析。结果表明,不同的裂解温度直接影响生成产物的类型和相对含量。4-氧代-β-大马酮可裂解出β-大马酮、4-氧代-β-紫罗兰酮、3,4,4-三甲基-环己-2-烯-1-酮和2,5,5-三甲基-环己-3-烯-1-酮等54种裂解产物。在550 ℃以下时,只有少量4-氧代-β-大马酮发生裂解; 在750 ℃时,几乎完全裂解,转移率达99.74%, 裂解产物达45种之多。随着裂解温度的升高,裂解产物越来越复杂,并出现有害物质如苯、甲苯、蒽和菲等。根据4-氧代-β-大马酮裂解产物相对含量的变化规律,对其裂解产物的形成机理进行了探讨,认为4-氧代-β-大马酮可能按照4种途径发生裂解。