Homologous Increments of Gas Chromatographic Retention Indices as Characteristic of Organic Compounds Polarity

Russian Journal of General Chemistry - Properties of homologous increments of gas chromatographic retention indices have been examined, iRI = RI ? 100int(M/14), where M is molecular weight...     

含氧化合物气相色谱保留指数的预测

通过对部分含氧化合物(醇、酯、醛、酮)在不同固定相不同柱温下的849个样本的气相色谱保留指数值(RI)与其部分参数:拓扑指数(mQ)、定位基参数(Sox)、固定液极性值(CP)及柱温(T)建立定量结构-色谱保留相关(QSRR)模型。分别利用多元线性回归(MLR)、偏最小二乘回归(PLSR)、人工神经网络(ANN)建模,同时采用内部及外部双重验证的办法对所得模型稳定性能进行深入分析和检验,建模计算值、留一法(LOO)交互检验(CV)预测值和外部样本预测值的复相关系数Rcum、QLOO和Rext分别为0.9832、0.9829和0.9836(MLR);0.9832、0.9830和0.9836(PLSR);0.9910、0.9909和0.9900(ANN)。结果表明:所建定量结构保留关系(QSRR)模型具有良好的稳定性和预测能力,较好地揭示了含氧化合物(醇、酯、醛、酮)在不同色谱条件下气相色谱保留指数的变化规律。     

新型原子类型拓扑指数模拟含氧化合物气相色谱保留指数

Quantitative structure-retention relationship (QSRR) model for the estimation of retention indices (RIs)of 39 oxygen-containing compounds containing ketones and esters was established by our newly introduced distance-based atom-type indices DAI. The useful application of the novel DAI indices has been demonstrated by developing accurate predictive equations for gas chromatographic retention indices. The statistical results of the multiple linear regression for the final model are r=0.9973 and s=8.23. Furthermore, an external test set of 10 oxo-containing compounds can be accurately predicted with the final equation giving the following statistical results: r pred=0.9966 and s pred=8.56.     

Estimation of High-Performance Liquid Chromatographic Retention Indices of Glucuronide Metabolites

Abstract

The retention indices of several glucuronide metabolites and their parent compounds were measured using a reversed-phase HPLC system. It was found that the typical glucuronide metabolite had a retention index 244 ± 31 units lower than the parent compound.     

Chromatographic Identification of Cyclohexane Chlorination Products by an Additive Scheme for the Prediction of Retention Indices

Identification of the products of free-radical chlorination of cyclohexane seems to be a complex analytical problem due to the following principal reasons: (1) the available reference information (both standard mass spectra and gas chromatographic retention indices, RI) is strongly restricted to the data for only few simplest congeners, (2) mass spectra of isomeric chlorinated derivatives are practically indistinguishable, and (3) the number of isomers increases with the growing number of chlorine atoms in the molecule until six. To solve this problem, the modified additive scheme for precalculation of the RIs of chlorinated cyclohexanes on standard non-polar polydimethyl siloxane stationary phases was proposed and used. This approach is based on the data for congeners with fewer number of chlorine atoms in the molecule; the principal feature is its applicability to a diastereomers. The final set of both experimental and precalculated RI values permits us to identify unambiguously more than 20 products of cyclohexane chlorination in reaction mixtures. Different modes of the quality control of evaluated retention indices are discussed.     

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。     

Chemometric Characterization of Differences in Chromatographic Retention Indices on Standard Polar and Nonpolar Phases as a Criterion for the Group Identification of Organic Compounds

The difference in retention indices on polar and nonpolar phases (RI) has been recommended since 1959 for the gas chromatographic group identification of organic compounds. However, reference data on this parameter for standard phases are presently lacking. To remedy this paradoxical situation at least in part, the paper presents statistically processed data on RI for 226 of the most comprehensively characterized series of compounds. The most important chemometric characteristics of the data sets are considered along with some ways using these values. Contrary to the currently accepted concepts, the additivity of RI values for the majority of series of polyfunctional compounds and their simpler analogues was proved. The main reasons for the absence of such additivity were considered.     

Comparison of the Topological and Dynamic Characteristics of Molecules for Calculating Retention Indices of Organic Compounds

This paper reports on a comparative analysis of the linear correlation equations relating the gas-chromatographic retention indices (RI) of several groups of isomeric organic compounds to the topological (Wiener and Hosoya indices) and dynamic (intramolecular energies estimated by molecular dynamic methods and the vibrational components of this energy estimated with simple models) parameters of molecules. It is shown that the choice of one of these parameters does not ensure the best approximation to RI, since the results depend on the chemical nature of substances. Correlations between all of the above quantities have been established. The correlations serve as a basis for physicochemical interpretation of the topological parameters of molecules as quantities proportional to the intramolecular vibrational and rotation energies.     

Retention Indices As the Best Reproducible Chromatographic Parameters for the Characterization of Phenolic Compounds in Reversed-Phase High-Performance Liquid Chromatography

A comparison of various methods for presenting the retention parameters of analyzed compounds in reversed-phase HPLC under the conditions of stepwise gradient elution demonstrated that retention indices (RIs) based on a standard scale of n-alkyl phenyl ketones exhibited the best reproducibility. However, a new procedure for calculating extrapolated RI values under these conditions should be developed for determining the RIs of the most hydrophilic compounds, which are eluted from a column before a reference component (acetophenone). With this procedure, the RIs of more than 40 phenolic and polyphenolic compounds were determined. The addition of spectroscopic characteristics to these RIs was responsible for the reliable identification of the above compounds in complex mixtures of extractive substances of plant origin.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 7, 2005, pp. 734–746.Original Russian Text Copyright © 2005 by Zenkevich, Kochetova, Larionov, Revina.     

拓扑-量子指数醛酮气相色谱保留指数及沸点的定量构效关系

通过对醛酮化合物分子结构特征及其气相色谱保留指数(RI)和沸点与分子结构间关系的研究,提出了分子极化效应指数(MPEI)、奇偶指数(OEI)、立体效应指数(SVij)、顶点度-距离指数(VDI)及键连接矩阵特征根(∑X1CH)等拓扑-量子结构参数,用多元线性回归(MLR)方法获得了醛酮类化合物的沸点及其在不同极性色谱柱上的气相色谱保留指数与这些拓扑-量子指数间良好的定量结构-性质相关(QSPR)模型,相关系数均大于0.99。5个分子结构参数具有明确的物理化学意义且易于计算和运用。与文献研究的比较结果表明:由上述分子结构参数得出的模型方程适用于各类醛酮化合物的气相色谱保留指数及沸点的预测且具有较好的稳定性和准确性。     

Use of a Simple Additive Scheme to Predict the GC Retention Indices of Aromatic Compounds with Different Structures

A simple algorithm is proposed for prediction of linear retention indices, RI, of organic compounds with different structures. The algorithm is based on the hypothesis that any structural moiety of a molecule contributes to gas chromatographic retention to a different extent, depending on its molecular environment. For a given moiety the mean structural increment (MSI) is calculated from the difference between the retention indices of two molecules, one containing it and one not, in different compound families. The mean of these values is the MSI for the corresponding moiety. The correlation between predicted and experimental values affords r ² = 0.992 and the mean relative error is 1.65% for n = 92 compounds.     

Estimation and Prediction of Gas Chromatography Retention Indices of Hydrocarbons in Straight-run Gasoline by Using Artificial Neural Network and Structural Coding Method

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Structural Characterization of Volatile Components of Rosa Banksiae Ait for Estimation and Prediction of Their Linear Retention Indices and Retention Times

The molecular electronegativity-distance vector （MEDV） was used to describe the molecular structure of volatile components of Rosa banksiae Ait, and QSRR model was built up by use of multiple linear regression （MLR）. Furthermore, in virtue of variable screening by the stepwise multiple regression technique, the QSRR models of 10 and 6 variables and linear retention index （LRI） 10, 7 and 6 varieables were built up by combinating MEDV with the Ultra2 column GC retention time （tR） of 53 volatile components of Rosa Banksiae Air. The multiple correlation coefficients （R） of modeling calculation values of QSRR model were 0.906, 0.906, 0.949, 0.943 and 0.949, respectively. The cross-verification multiple correlation coefficients （RCV） were 0.903, 0.904, 0.867, 0.901 and 0.904, respectively. The results show that the models constructed could provide estimation stability and favorable predictive ability.     

胺类化合物气相色谱保留指数与结构的相关性研究

应用Ａｍ指数和引力指数Ｇ１对在３种体系下的胺类化合物的气相色谱保留指数和结构进行了相关性研究,并运用最佳子变量集算法和人工神经网法进行了计算分析,在非极性固定相ＯＶ－１０１和极性固定相ＯＶ－２２５和ＮＧＡ下均获得了比较好的相关模型。     

A QSRR Study on the Chromatographic Retention Indices of Hydroxylated Polychlorinated Biphenyls

Hydroxylated Polychlorinated Biphenyls (HO-PCBs) are the metabolite of polychlorinated biphenyls and have drawn much attention because they have hazard on human health and ecosystems. Molecular connectivity index calculation has been performed for 19 HO-PCB compounds. A number of statistically based parameters have been extracted. Linear relationship between chromatographic retention index (RI) and the molecular connectivity index of 15 compounds in the training set has been established by multiple linear regression method. The other 4 HO-PCBs are used as the external test set. The result shows that the parameters can be well used to express the quantitative structure-retention relationship (QSRR) of HO-PCBs. Good stability and predictive ability have been demonstrated by leave-one-out cross-validation and the external test set.     

Retention Indices for Most Frequently Reported Essential Oil Compounds in GC

Retention indices were evaluated for one hundred most commonly reported essential oil compounds in gas chromatography (GC) using a large retention index database. Retention data are presented for three types of stationary phases: dimethyl silicone, dimethyl silicone with 5% phenyl groups, and polyethylene glycol stationary phases. The data evaluations are based on the treatment of multiple measurements with the number of data records ranging between 30 and 470 per compound. Data distribution analysis was limited to temperature programming conditions. Data reported include the most probable value of retention index, average and median values, standard deviation, and confidence intervals. The values of most probable retention indices correspond to frequently used GC conditions of measurements (temperature program, column parameters, gas flow conditions). The results are compared with data from several available retention index collections.     

新拓扑指数A_m在构效关系研究中的应用──Ⅰ.对烃类气相色谱的保留指数的分析

该文研究了本实验室提出的Am拓扑指数和烃类气相色谱保留指数的相关关系，并与分子联接性指数进行了对比分析，得到了比较理想的相关方程，使相关系数分别达到0.993以上。