气相色谱QSRR研究在质谱谱库检索定性中的应用

 对质谱谱图相似的多取代烷基苯各位置异构体,根据一种从苯、单取代烷基苯及双取代烷基苯保留指数预测相关多取代烷基苯保留指数的方法,测定了基础化合物在OV－1毛细管柱上的保留指数,预测了相关多取代烷基苯在OV－1上的保留指数。利用该保留数据,结合质谱,给予了正确定性,从而解决了质谱谱库检索定性时对于各位置异构体难于定性的困难。     

气相色谱-质谱联用结合保留指数分析仙鹤草挥发性成分

提出了一个分析仙鹤草挥发油成分的方法。采用水蒸汽蒸馏法提取仙鹤草挥发性成分,气相色谱-质谱(GC-MS)结合保留指数双重定性,按峰面积归一化法求出各挥发性成分的相对含量,共检测出67个组分,质谱结合保留指数定性鉴定出48个主要挥发性成分,占挥发性成分总含量的87.35%;含量较高的组分为雪松醇(17.50%)、α-蒎烯(11.60%)、伽罗木醇(6.29%)、α-萜品醇(4.90%)和乙酸龙脑酯(4.37%)。方法定性结果更为准确,能为进一步研究仙鹤草化学组分和质量控制提供基础。     

GC/MS法结合保留指数分析香青花与叶挥发油的化学成分

研究香青花与叶挥发油的化学成分。采用同时蒸馏萃取法(SDE)提取香青花与叶中的挥发油,使用气相色谱-质谱联用技术(GC-MS)获得总离子流图,各色谱峰相应的质谱图经过NIST11.L标准谱库检索,辅助保留指数比对定性,并采用峰面积归一化法进行定量分析,计算各成分的相对百分含量。从香青花与叶挥发油中共鉴定出41种物质,相同成分有15种,花与叶挥发油的化学成分含量差异较大,其中花挥发油中主要成分为α-葎草烯(13.46%)、环氧化葎草烯II(8.97%)、Ar-姜黄烯(8.50%)、δ-杜松烯(6.99%)等;叶挥发油中主要成分为α-葎草烯(17.47%)、α-蒎烯(15.17%)、Ar-姜黄烯(8.27%)、(E)-石竹烯(6.06%)等。采用GC-MS法结合保留指数鉴别香青花与叶挥发油中的同分异构体,提高了药用植物不同部位挥发油成分定性的准确性,为香青药用价值的开发和应用提供了参考。     

谱图相似度分析结合保留指数对单萜烯同分异构体的GC—MS定性分析

运用欧氏距离的最短距离聚类分析法,对在质谱数据库NIST02.L检索到的37种单萜烯同分异构体的93张质谱图进行了分类.结果显示,单萜烯被分成5类,大部分单萜烯聚到1类,包括30种单萜烯的77张质谱图.但部分谱图很近似,仅用传统的质谱库匹配鉴定其结构存在一定的困难.采用改进的谱图相似度分析结合保留指数实现了有效定性,并将该方法用于实际样品的定性分析.     

萜类化合物的QSRR研究及其在结构鉴定中的应用

采用顶空固相微萃取(SPME)-气相色谱质谱(GC-MS)联用技术分析石香薷和腊梅鲜花中的萜类化合物, 通过保留指数与质谱解析相结合, 分别对化合物进行结构鉴定, 共鉴定出17种单萜化合物, 30种倍半萜化合物. 采用遗传算法(GFA)分别对单萜及倍半萜化合物建立定量结构-色谱保留关系(QSRR)预测模型, 并对该模型进行显著性及预测能力的检测. 同时, 利用计算所得到的模型分别对随机选取的几个萜类化合物进行保留指数预测. 结果表明: 计算保留指数与预测保留指数接近, 模型预测性能较好. 该研究为各种单萜化合物及倍半萜化合物保留指数的预测提供了一种有效手段, 同时, 为建立有效的GC-MS定性方法提供了一定的依据.     

气相色谱保留指数定性方法研究进展

综述了程序升温气相色谱保留指数,I^T与Kovats恒温保留指数,之间的关系、I^T的标准化和重现性问题以及定量结构保留指数关系(QSRR)研究进展;对于应用特殊检测器和极性柱定性、对多环芳烃和多氯联苯类物质利用保留指数定性的情况,选择非正构烷烃类同系物作为参考标准时准确性大为提高,比较了由此得到的保留指数与Kovats保留指数的关系;展望了利用保留指数定性的前景。     

气相色谱-质谱法定性定量分析烟叶挥发性香气成分

本文研究了质谱去卷积算法在化合物结构定性中的作用。采用质谱去卷积和质谱库检索、色谱保留指数、标样定性等相结合的方法从烟叶样品中鉴定出118个挥发性香气成分,其中57个醛酮类化合物、23个醇类化合物、16个含氮类化合物、7个有机酸类化合物、15个其它化合物。采用定量离子进行定量,有效降低了重叠峰干扰,使色谱积分结果更为真实准确。对所鉴定的化合物进行重复性考察,结果表明有60.2%的化合物的相对标准偏差(RSD)小于20%,80.5%的化合物的RSD小于30%。线性响应考察结果表明有80个化合物的线性相关系数(R2)在0.90以上,适合于定性或定量分析。     

色谱隶属函数定性研究

 ]采用模糊集有关理论对所有可能影响保留指数定性准确度因素通过隶属函数表示出来。本方法弃之以传统“定性窗口”的概念，代之以隶属度，并根据最大隶属原则定性。不仅如此，本方法尚具有“窗口”定性法不具备的多种优点，使得定性可靠性大大增加。而且本方法还为定性结果优化、因素校正提供了有效的手段。经过对任意多阶方式下石脑油组分定性分析证明了其特有的作用。     

移动子窗口中搜索法在紫丁香挥发油气相色谱-质谱分析中的应用

基于气相色谱-质谱仪产生的二维数据,采用移动子窗口搜索法,以纯组分峰为标准对同一样品在不同色谱柱上或不同样品在相同色谱柱上所获得的总离子流图的一定保留时间范围内搜索,可以得到目标化合物的流出区域,取其中点作为保留时间,从而计算各化合物在不同极性色谱柱上的程序升温保留指数.采用GC-MS与色谱保留指数相结合的方法,分别在HP-5MS和DB-35MS柱上,于80℃～290℃(4℃/min)的升温程序下,对黑龙江产紫丁香花蕾与花挥发油的分析结果表明,辅以化学计量学方法和双柱色谱保留指数定性比单用GC-MS定性结果更加快速可靠.     

气-质联用/沸点-Lee保留指数法快速分析胆固醇裂解产物

利用高分辨裂解气相色谱-质谱（HRPyGC-MS）技术在600、750、900℃条件下对胆固醇进行裂解,通过NIST02质谱数据库、沸点和Lce保留指数法对胆固醇裂解产物进行了定性分析;利用峰面积归一化法对其中48种化合物包括脂肪族碳氢化合物和芳香族碳氢化合物进行了相对含量分析,组分含量最小为0.08%,最大为65.07%.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

Mechanism of action of base-catalyzed oxygenation of phenol derivatives

Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Study of hydration of two cements of different strengths

Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M_o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700^oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

化学计量中不确定度评定研究进展

测量不确定度是表征合理地赋予被测量之值的分散性的参数。本文针对化学计量不确定度评定基础模型仅适用于线性模型、概率分布为正态分布或缩放位移t分布等局限,介绍了近年来不确定度评定的研究热点:蒙特卡罗方法(Monte Carlo Method,MCM),不确定度评定的来源、评定概念、评估方法及其发展过程,扩大了测量不确定度评定与表示的适用范围。