多取代烷基苯Kovats保留指数预测

提出一种从苯、单取代烷基苯及同取代基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简单、准确的新方法。只需做较少的实验,便可预测大量相关化合物的保留指数。研究表明,在４种固定相ＯＶ－１０１,Ｓｑｕａｌａｎｅ,ＳＥ－３０,ＰＥＧ－２０Ｍ上,计算出每一根柱子的保留指数Ⅰ的标准偏差在±２．４ｉ．ｕ．～±３．７ｉ．ｕ．之间。     

直链单烯烃保留指数与分子结构关系的研究

根据同系直链单烯烃保留指数与同碳数正构烷烃保留指数差值与分子碳数间关系曲线拟合,提出预测同系直链单烯烃保留指数的准确公式。在ＳＱ,ＰＦＥ,ＰＥＧ－４０００上,利用所提出的公式对检验集中化合物保留指数预测值与实测值差的标准偏差在±０．９ｉ．ｕ．～±１．５ｉ．ｕ．之间。并且研究发现,同碳数、同几何构型直链单烯烃各位置异构体分子中双键位置与化合物保留指数具有指数关系。首次提出依据分子中双键位置预测其保留指数的准确公式。公式适合各种不同极性固定相。     

直链单炔烃保留指数与分子结构关系研究

根据同系直链单炔烃保留指数与同碳数正构烷烃保留指数差值与分子碳数间关系曲线拟合，提出预测同系直链单炔烃保留指数的较准确公式。研究并发现同碳数直链单炔烃各异构体分子中三键位置与化合物保留指数具有指数关系，首次提出了据分子中三键位置预测其保留指数的较准确公式。解决了从低碳数直链单炔烃保留指数预测高碳数直链单炔烃保留指数问题。     

饱和醇结构-保留定量相关的人工神经网络模型

以拓扑指数为结构描述符，用基于Levenberg-Marquardt优化的BP神经网络建立了醇类化合物的结构与色谱保留值的相关性模型，用于未知醇类化合物在SE－30和OV－3两根色谱柱上保留指数的同时预测，其学习速率优于文献中普通BP神经网络法，预测准确度与普通BP神经网络法接近，但优于多元线性回归法，因而是一种较好的预测有机化合物气相色谱保留指数的方法。     

石脑样品的族组成分析

用气相色谱以程序升温方式分析了石脑油,并将各组分程序升温保留时间转移为恒温保留指数。以各组分在OV－1和SE－54固定相上、同一柱温下的保留指数差及在各柱上的温度系数为3因素进行斜交因子分析和本征矢量旋转,给出了石脑油样品的族组成值,经色谱－质谱仪分析验证了结果的正确性,为石脑油样吕的族组成分析提供了一种新方法。     

芳香族化合物在苯并系列冠醚聚硅氧烷固定液上的保留机理

分离测得了不同结构芳香族化合物在单苯并（ＰＳＯ－Ｂ－３－１５Ｃ５或１８Ｃ６）、双苯并（ＰＳＯ－ＤＢ－３－１５Ｃ５）和双苯并双叔丁基（ＰＳＯ－ＤＴＢ－３－１５Ｃ５）取代的１５Ｃ５聚硅氧烷固定液上的保留指数、相对保留值以及１０组异构体的热力学参数──溶解焓△Ｈｓ,溶解摘△Ｓｓ和自由能△Ｇ;研究探讨了冠醚环上不同苯基取代的固定液结构对芳香族位置异构体保留行为的影响;通过热力学参数对不同冠醚柱子选择性的表征,证明了苯并系列冠醚固定液对芳烃位置异构体的良好选择分离,主要取决于冠醚环腔的高电子云密度所产生的定向力和强诱导力以及分子和冠醚环腔的适应程度,特别是空间位阻效应起了重要作用。     

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.     

烷基苯类化合物气相色谱保留指数与分子结构的相关性研究

利用分子力学和量子化学方法计算出烷基苯类化合物的分子结构描述参数,用逐步回归法建立烷基苯类化合物在不同极性色谱柱上的QSRR模型。烷基苯类化合物在不同极性色谱柱上的气相色谱保留指数与其分子结构描述参数之间具有较好的线性关系。建立了在不同极性色谱柱上的烷基苯类化合物的色谱保留QSRR模型,并预测烷基苯类化合物的色谱保留值,结果具有较好的稳定性和准确性。     

多氯萘的气相色谱保留指数与其结构参数的定量关系

在B3LYP/6-31G*水平上计算了76个多氯萘分子,将计算得到的结构参数和热力学参数作为理论描述符引入到与气相色谱保留指数(RI)相关的多元回归分析中,建立了拟合度高、物理意义明确、预测能力强的保留时间-结构参数的相关方程(模型Ⅰ)(r2=0.9957);再以氯原子的取代个数和相互位置作为理论描述符,得出另一模型(模型Ⅱ)(r2=0.9967)。找出了影响多氯萘保留时间的主要因素。     

直链醇、烷基苯气相色谱保留指数之比与其正辛醇/水分配系数的相关性

通过研究直链醇、烷基苯等有机物气相色谱保留指数与其正辛醇／水分配系数的关系得出,在极性相异固定相上保留指数之比Im/n与其正辛醇／水分配系数的对数值logkow之间有较好的线性相关性。因而由保留指数能很好的预测分配系数,从而为直链醇、烷基苯分配系数的测定提供了一种简便准确的新方法。     

Kovats and lee retention indices determined by gas chromatography/mass spectrometry for organic compounds of environmental interest

Retention indices of standard organic compounds of environmental interest were determined by gas chromatography/mass spectrometry, using a DB-5 fused-silica capillary column. Retention indices are useful references for tentative compound identification by gas chromatography, or confirmation by gas chromatography/mass spectrometry. They provide elution order for isomers that might be indistinguishable based on mass spectra. Modified Kovats and Lee retention indices are given for polycyclic aromatic hydrocarbons; sulfur heterocycles; nitrogen heterocycles; aromatic amines; oxygen heterocycles; phenols; alcohols; ketones; alkanes; nitriles; and methylesters of fatty, dicarboxylic, and aromatic acids for comparison and reference. Retention index values for heterocycles by gas chromatography/mass spectrometry are comparable with gas chromatography values previously reported.     

Analysis of the chemical composition of the essential oil of Polygonum minus Huds. using two-dimensional gas chromatography-time-of-flight mass spectrometry (GC-TOF MS)

The essential oil in leaves of Polygonum minus Huds., a local aromatic plant, were identified by a pipeline of gas chromatography (GC) techniques coupled with mass-spectrometry (MS), flame ionization detector (FID) and two dimensional gas chromatography time of flight mass spectrometry (GC x GC-TOF MS). A total of 48 compounds with a good match and high probability values were identified using this technique. Meanwhile, 42 compounds were successfully identified in this study using GC-MS, a significantly larger number than in previous studies. GC-FID was used in determining the retention indices of chemical components in P. minus essential oil. The result also showed the efficiency and reliability were greatly improved when chemometric methods and retention indices were used in identification and quantification of chemical components in plant essential oil.     

Tracking juniper berry content in oils and distillates by spectral deconvolution of gas chromatography/mass spectrometry data

The complex nature of botanicals and essential oils makes it difficult to identify all of the constituents by gas chromatography/mass spectrometry (GC/MS) alone. In this paper, automated sequential, multidimensional gas chromatography/mass spectrometry (GC-GC/MS) was used to obtain a matrix-specific, retention time/mass spectrometry library of 190 juniper berry oil compounds. GC/MS analysis on stationary phases with different polarities confirmed the identities of each compound when spectral deconvolution software was used to analyze the oil. Also analyzed were distillates of juniper berry and its oil as well as gin from four different manufacturers. Findings showed the chemical content of juniper berry can be traced from starting material to final product and can be used to authenticate and differentiate brands.     

溶剂辅助蒸馏-气相色谱-串联质谱法分析酿酒葡萄中的游离态萜烯类化合物

应用气相色谱-串联质谱联用技术(GC-MS/MS)和溶剂辅助蒸馏技术(SAFE)对4种酿酒葡萄中的游离态萜烯类化合物进行了研究。采用恒温振荡法浸提葡萄中的成分,溶剂辅助蒸馏法除去不挥发性成分,提取液经氮吹浓缩后进行GC-MS/MS分析。实验中优化了SAFE条件(循环水浴温度、样品流量)。通过NIST05a谱库检索、标准品的保留指数（RI值）对比及参考文献的RI值对比分析，在4种葡萄中共鉴定出30种萜烯类化合物,其中包括10种单萜烯类化合物、18种倍半萜烯类化合物、1种二萜烯类化合物以及1种三萜烯类化合物。在蛇龙珠葡萄中检出了28种萜烯类化合物,在梅鹿辄、赤霞珠和品丽珠葡萄中分别检出了16，17和16种萜烯类化合物。在蛇龙珠葡萄中检出了17种倍半萜烯类化合物,远多于其他3种酿酒葡萄。通过半定量分析，发现在赤霞珠葡萄中单萜烯类化合物含量较高,在蛇龙珠葡萄中倍半萜烯化合物含量较高。实验结果表明,该方法适用于酿酒葡萄中游离态萜烯类成分的定性和定量分析。     

Compositional studies of high-temperature coal tar by GC/FTIR analysis of light oil fractions

Summary A method for determination of the composition of the light oil fractions in high-temperature coal tar by means of distillation, followed by gas chromatography on a crosslinked fused-silica, capillary column coated with optimum amount of stationary phase and identification by capillary gas chromatography/Fourier transform infrared spectrometry combined with GC retention indices (GC/FTIR-RI) is described. This method was effectively used to identify complex mixture such as coal tar without any standard samples, especially, adapted for isomeric compounds. More than 60 and 50 compounds were also separated and identified respectively in light oil fractions. This shows the capability of the capillary GC/FTIR combined with GC retention indices to identify isomers not accomplished by GC/MS.     

Boundary-effect activated dissociation in ion trap tandem mass spectrometry

The potential of boundary-effect activated dissociation (BAD) in ion trap tandem mass spectrometry (MS/MS) is discussed. Several classes of compounds were investigated and the BAD product ion tandem mass spectra were compared with those from collisionally activated dissociation (CAD) where an auxilliary r.f. ‘tickle’ voltage is used. The energy deposition in BAD MS/MS is generally lower than that for optimized CAD, but the experiments are easier to perform. An example of the BAD MS/MS of C₁₀ alkylbenzenes and benzothiophene in diesel fuel using gas chromatographic introduction and predicted r.f. and d.c. voltages is presented.     

Analysis of the volatile compounds in Senecio scandens Buch-Ham by gas chromatography-tandem mass spectrometry based on diversified scan technologies

Static headspace gas chromatography-tandem mass spectrometry was used to identify volatile compounds from Senecio scandens Buch-Ham. The elemental composition of compounds was confirmed by exploiting the tandem mass spectra of isotopic peaks from the precursor ion. Some isomers were well distinguished by the diversified scan technologies of tandem mass spectrometry (MS/MS). The MS/MS included a product ion scan, a precursor ion scan and a neutral loss scan. The results showed that 46 volatile compounds were completely identified, and the great of majority compounds were α-pinene (11.93%), n-caproaldehyde (9.02%) and dehydrosabinene (6.22%). This qualitative method is convenient and accurate and can be considered as a complementary identification method for the qualitative analysis of volatile compounds in complex samples.     

Perdeuterated n-alkanes for improved data processing in thermal desorption gas chromatography/mass spectrometry I. Retention indices for identification

The identification of organic compounds by GC/MS is useful in various areas such as fuel, indoor and outdoor air and flavour and fragrance applications. Multi-compound mixtures often contain isomeric compounds which have similar mass spectra and sometimes cannot be unambiguously identified by library search alone. Retention indices can help with confirmation of identification if they are reproducible. Using perdeuterated n-alkanes as a reference series for calculation of retention indices in GC/MS has a clear benefit because of the distinctive ion trace of m/z 34. Thermal desorption is useful for analysis of volatile organic compounds (VOCs) in air after sampling on appropriate sorbent cartridges. Comparison of indices between three systems, consisting of a thermal desorption unit, a gas chromatograph and a mass spectrometer, showed good agreement for compounds with well-defined peaks, whereas retention times varied.     

Positive confirmation of identity of doping agents using gas chromatography-mass spectrometry with Fourier transform infrared spectrometry

During the past two decades, the use of retention times in gas chromatography has been augmented by mass spectrometric data. By providing both the retention indices and spectrometric data, this technique has greatly improved gas chromatographic identification analysis. However, although gas chromatography-mass spectrometry has become pre-eminent, several drawbacks still remain. The mass spectral library often gives erroneous identifications when concentrations near the detection limit are analysed, when gas chromatographically interfering substances are present, or when structural isomers or compounds exhibiting identical retention behaviour are analysed. Linked with gas chromatography-mass spectrometry, Fourier transform infrared spectroscopy can be a powerful complementary technique in peak identification analysis. Some spectral data to illustrate this point are presented.     

System for calculating the linear temperature-programmed retention indices of polycyclic aromatic compounds

Theoretical procedures have been used to predict linear temperature-programmed retention indices for polycyclic aromatic compounds. It is possible to calculate such indices for polycyclic aromatic compounds in some practical situations in which the compounds cannot be eluted during a simple linear temperature program. The theory has been tested for a number of polycyclic aromatic hydrocarbon (PAHs) in single- and multi-plateau temperature-programmed gas chromatography with SE-52 as the stationary phase. This method will extend the applicability of linear retention indices for the identification of the isomers of polycyclic aromatic compounds.