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Totally found 32 items.

  • [期刊] High-pressure densities and interfacial tensions of binary systemscontaining carbon dioxide + n-alkanes: (n-Dodecane, n-tridecane,n-tetradecane)
    Experimental isothermal densities and interfacial tensions for the binary systems carbon dioxide + n-dodecane, carbon dioxide + n-tridecane and carbon dioxide + n-tetradecane at 344.15 K and over thepressure range 0.1 to 12, 13 and 14 MPa, are reported. Measurements are carried out on a combined devicethat includes a high-pressure vibrating tube densimeter and a high-pressure pendant drop tensiome-ter. The theoretical modeling is based on the use of square gradient theory as applied to the statisticalassociated fluid theory (SAFT) equation of state. The experimental bulk phase equilibrium densities andinterfacial tensions obtained are in very good agreement with the theoretical modeling. By seamlesslycombining experimental and modeling approaches we are able to simultaneously predict phase equi-librium and interfacial properties. For the systems and conditions studied we do not observe mass normolar barotropic inversion; the interfacial tensions decrease as the pressure (or liquid mole fractionof carbon dioxide) and/or as the n-alkane molecular chain length increases. The surface relative Gibbsadsorption of the species along the interfacial region is reported; carbon dioxide is adsorbed along theinterfacial region, whereas n-alkanes (n-dodecane, or n-tridecane or n-tetradecane) do not exhibit anyspecial adsorption activity. The adsorption of carbon dioxide increases with pressure and with the chainlength of the n-alkane.
  • [期刊] Densities and Viscosities for the Ternary System of Isopropylcyclohexane (1) + n-Tridecane (2) + n-Butanol (3) and Corresponding Binaries at T=293.15 to 333.15 K
    It has been proven that alcohols can regulate the performance of aviation fuels. In this work, the densities (rho) and viscosities (eta) for the ternary system of isopropylcyclohexane (1) + n-tridecane (2) + n-butanol (3) and the corresponding binary systems have been measured to understand the physical properties of endothermic hydrocarbon fuel with alcohol over the whole composition range at temperatures from 293.15 to 333.15 K under atmospheric pressure (p = 0.1 MPa). The Redlich-Kister equation has been used to fit the excess molar volumes ((E)(Vm)) and viscosity deviations (Delta(eta)) of binary systems, while four semiempirical equations (Singh, Cibulka, Nagata-Tamura, and Redlich-Kister) have been applied to correlate (E)(Vm) and Delta(eta )of the ternary system. For all binary systems, the values of (E)(Vm) are positive. The values of Delta(eta) for binary systems containing n-butanol are all negative. For the ternary system, the values of (E)(Vm) are all positive and the values of Delta(eta) are all negative over the entire concentration range. All results have been interpreted with the perspective of intermolecular interaction and structural effect.
  • [期刊] 基于GC-MS同时测定蓬莪术及其醋制品挥发油中β-榄香烯、莪术醇、吉马酮、新莪术二酮的含量
    建立一种同时测定蓬莪术及其醋制品挥发油中β-榄香烯、莪术醇、吉马酮、新莪术二酮4种主要有效成分的分析方法,为完善蓬莪术和醋制品挥发油及其制剂的质量控制提供依据,并为进一步优化蓬莪术炮制工艺及机制研究奠定基础.采用GC-MS,以正十三烷为内标物,同时对蓬莪术挥发油中4种主要有效成分进行定量分析.色谱条件为Agilent 19091 S-433柱(0.25 μm×250 μm×30 m),进样口温度250℃,初始温度60℃,保持1 min,以5℃·min-1速率升温至110℃,保持5 min,以1℃·min-1速率升温至140℃,以5℃·min-速率升温至160℃,以10℃·min-速率升温至240℃,载气为氦气,流速1.0mL·min-1,进样量1 μL.质谱条件为EI源,轰击电压70 eV;正离子模式,离子源温度200℃,以选择离子检测(SIM)定量,选择m/z 85.1,93.1,121.1,107.1,180.1分别为正十三烷、β-榄香烯、莪术醇、吉马酮、新莪术二酮的检测离子.蓬莪术挥发油中β-榄香烯、莪术醇、吉马酮、新莪术二酮全部检出,分离效果较好;在各自浓度范围内均有良好的线性关系;平均回收率在98.2%~101%.经过方法学验证,该方法可有效地对蓬莪术和醋制品挥发油及其相关制剂的质量进行控制.
  • [期刊] C 11-C 14烷烃与月桂酸甲酯体系等压汽液平衡
    在5.00 kPa下,用Rose釜测定了正十一烷-月桂酸甲酯、正十二烷-月桂酸甲酯、正十三烷-月桂酸甲酯和正十四烷-月桂酸甲酯4个二元体系的汽液平衡数据,并对所测数据进行了热力学一致性检验,结果表明所有的实验数据均符合热力学一致性.分别用NRTL、UNIQUAC和Wilson活度系数模型对实验数据进行关联,得到了各个模型的二元交互作用参数,并用这三个模型及得到的参数计算了平衡温度及汽相组成,计算结果与实验数据吻合较好.
  • [期刊] 盐酸雷尼替丁中二氯甲烷残留量的测定
    采用液相微萃取与气相色谱联用技术测定雷尼替丁中二氯甲烷的残留量。以使用正十三烷为有机溶剂,萃取时间30 min,萃取温度60℃,萃取液滴体积2μL。得出测试结果为二氯甲烷的线性回归方程y0.019 4x+0.054 7,相关系数R20.973 3,方法最低检测限为0.273μg/g,相对标准偏差为0.517%,加标回收率为93.6%~102%。该方法操作简单、数据可靠。
  • [期刊] 盐酸雷尼替丁中二氯甲烷残留量的测定
    采用液相微萃取与气相色谱联用技术测定雷尼替丁中二氯甲烷的残留量。以使用正十三烷为有机溶剂,萃取时间30 min,萃取温度60℃,萃取液滴体积2μL。得出测试结果为二氯甲烷的线性回归方程y0.019 4x+0.054 7,相关系数R20.973 3,方法最低检测限为0.273μg/g,相对标准偏差为0.517%,加标回收率为93.6%~102%。该方法操作简单、数据可靠。
  • [期刊] 顶空液相微萃取-气相色谱法测定盐酸雷尼替丁中二氯甲烷和三氯甲烷的残留量
    采用顶空液相微萃取与气相色谱联用技术测定雷尼替丁中二氯甲烷和三氯甲烷的残留量。自制了萃取液保护装置。考察了萃取溶剂的种类、萃取时间、萃取温度、萃取液的体积对二氯甲烷和三氯甲烷萃取效果的影响。以正十三烷为萃取剂,在60℃下萃取30min,萃取液滴体积2μL。二氯甲烷含量在1~10μg/g范围内与色谱峰高呈线性关系,相关系数(r^2)为0.973 3;三氯甲烷含量在1~10μg/g范围内与色谱峰高呈线性关系,r^2为0.972 4。二氯甲烷和三氯甲烷的最低检出限分别为0.027 3μg/g和0.041 0μg/g,加标回收率分别为93.6%~102%和98.1%~103%。方法简便易行,测定结果准确。
  • [期刊] 白花鬼针草化学成分研究
    目的:研究白花鬼针草化学成分.方法:利用硅胶柱色谱对白花鬼针草的化学成分进行分离和纯化,采用EI-MS、1 H-NMR、13C-NMR等波谱方法结合理化性质鉴定化合物结构.结果:从白花鬼针草中分离鉴定了10个化合物,分别为:木栓酮(1)、正十三烷(2)、木栓醇(3)、β口-谷甾醇(4)、21a-羟基木栓烷-3-酮(5)、豆甾醇(6)、羽扇豆醇(7)、豆甾醇-3-O-β-D-葡萄糖苷(8)、二十烷酸(9)和木栓烷-3β-醇-27-酸(10).结论:10个化合物均为首次从该植物中分离得到.
  • [期刊] 气相色谱法测定氯甲酸正辛基酯
    采用气相色谱法,以正十三烷为内标物,对光气化产品氯甲酸正辛基酯进行测定,该法简便、快速,精密度好,准确度高,且分析成本低.
  • [期刊] 冰冻野地瓜果实香气成分的SPME-GC-MS分析
    建立野地瓜果实中香气成分的SPME-GC-MS检测方法。同时,优化固相微萃取的条件:萃取温度50℃,萃取时间40 min,萃取时加入8 g Na Cl电解质。冰冻后野地瓜果实中共检测出152种挥发性物质,占总检出物质的99.03%。主要为酯类,占33.06%;醇类,占13.14%;烷烃类,占13.38%;还有酮类,醛类,酸类等物质。含量较高的10种香气成分依次为愈创木酚(14.71%),环丁烷羧酸十二烷基酯(13.54%),正十三烷(6.05%),2-十三烷酮(4.72%),环己硅氧烷(4.44%),环丁烷羧酸癸酯(4.18%),甲基壬基甲酮(3.62%),乙酸(2.98%),环戊烷羧酸十三酯(2.48%),2-十四烷醇(2.31%),等。
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