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Summary Gas chromatographic retention indices for 23 hydrocarbons were determined on BP-1 dimethylsiloxane between 45 and 65°C. From the data measured unified retention indices were calculated. These values agree well with the corresponding experimental values. The values of unified retention indices obtained on BP-1 are compared with those determined on OV-101 and on squalane. The differences between the unified and the experimental retention indices on BP-1, OV-101 and squalane columns are shown. 相似文献
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Published retention indices of acyclic alkenes C5-C7 on squalane and polydimethylsiloxane as stationary phases were investigated, and reliable retention indices of alkenes from various sources were converted to separation systems used in a laboratory. Retention indices measured on available authentic commercial alkenes and on alkenic fraction of gasoline, published retention indices as well as means of GC-MS were used for verification of calculated retention indices. Retention of some gas chromatographic unseparated isomer pairs was obtained by mass spectrometric deconvolution using a specific single-ion monitoring. On the basis of these retention data, C5-C7 alkenes were identified and analyzed in the gasoline from fluid catalytic cracking. In the gasoline all 59 acyclic C5-C7 isomeric alkenes were determined at significantly different concentration levels. 相似文献
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直链单炔烃保留指数与分子结构关系研究 总被引:2,自引:0,他引:2
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。 相似文献
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Chromatographic retention indices on a standard nonpolar poly(dimethylsiloxane) phase were determined for 33 α-alkynols and their 27 dehydration products (conjugated alkenynes). The resulting data are proposed to be verified using the retention indices of acetylenic alcohols estimated by the additive scheme from the retention indices of isostructural alkynes with the inclusion of increments for secondary and tertiary hydroxy groups. The analogous approach to data the verification of data for alkenynes is based on correlation of their retention indices with normal boiling points. 相似文献
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Direct conversion of isothermal to temperature programmed indices is not possible. In this work it is shown that linear temperature programmed retention indices can only be calculated from isothermal retention data if the temperature dependence of both the distribution coefficients and the column dead time are taken into account. Procedures are described which allow calculation of retention temperatures and from these, accurate programmed retention indices. Within certain limits the initial oven temperature and programming rate can be chosen freely. The prerequisite for this calculation is the availability of reliable isothermal retention data (retention times, retention factors, relative retention times, or retention indices) at two different temperatures for one column. The use of compiled isothermal retention indices at two different temperatures for the calculation of retention temperatures and thus temperature programmed indices is demonstrated. For the column for which programmed retention indices have to be determined, the isothermal retention times of the n-alkanes and the column dead time as a function of temperature have to be known in addition to the compiled data for a given stationary phase. Once the programmed retention indices have been calculated for a given column the concept allows the calculation of temperature programmed indices for columns with different specifications. The characteristics which can be varied are: column length, column inner diameter, phase-ratio, initial oven temperature, and programming rate. 相似文献
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Summary In order to determine the applicability of retention indices, based on the alkylarylketone scale, as the basis of a reproducible
method of reporting retentions, the separation of ten barbiturates and a set of column test compounds were examined on an
octadecylsilyl bonded silica (ODS-Hypersil) column with methanol-buffer pH 8.5 as eluent. The effects on the capacity factors
and retention indices, on changing the eluent composition, pH, ionic strength and temperature, showed that the retention indices
of the barbiturates were much less susceptible to minor changes in the eluent than the capacity factors. For non-ionised compounds
the retention indices were virtually independent of the experimental conditions.
Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984 相似文献
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Retention indices of 28 symmetric dicarboxylic acid esters containing from two to six carbon atoms in the acid residue were determined experimentally. The temperature dependences of the retention indices were linear. Equations were proposed to predict the retention indices for symmetric and mixed C2–C6 dicarboxylic acid esters. 相似文献
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Summary The retention of hydrocarbons present in the C5 pyrolysis fraction of gasolines on the stationary phases squalane and methylsilicone oil JXR at 30, 40 and 50°C was investigated
by capillary gas chromatography. The unified retention indices of the hydrocarbons were also calculated on squalane. The retention
indices obtained on these two phases were interrelated and the quantitative relationship with the structure of the solutes
was studied.
Equations based on the unified retention indices calculated on squalane and some selected structural elements of the solutes
permit the calculation of their retention on methylsilicone with sufficient accuracy. 相似文献
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I. V. Gruzdev M. V. Alferova B. M. Kondratenok I. G. Zenkevich 《Journal of Analytical Chemistry》2011,66(5):504-509
Gas chromatography retention indices were experimentally determined for 27 chloro- and bromo-substituted anilines on the standard
non-polar polydimethylsiloxane stationary phase; a procedure for the estimation of retention indices for any other species
of the studied class was proposed. The computational algorithm is based on a modified additive scheme equivalent to the assembly
of the target structure from simpler molecules characterized by retention indices, using their addition and subtraction. 相似文献
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A García-Raso M I Páez I Martínez-Castro J Sanz M M Calvo 《Journal of chromatography. A》1992,607(2):221-225
Trimethylsilyl ethers of seventeen disaccharides were injected on two stationary phases and their retention indices were calculated. Multiple linear regression was used to discuss relationships between retention indices and structural features of disaccharides. 相似文献
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In reversed phase liquid chromatography, the retention indices of benzene and nine mono substituted benzenes with different functionality based on the alkan-2-ones and alkyl aryl ketones retention index standards have been determined by the application of two new mathematical adaptation methods, viz. a multiparametric least-squares regression iterative method based on the determination of the adjusted retention times and a local cubic interpolation method directly using the total retention times. The two methods were applied to two types of columns. The first group includes four octadecyl-C18 columns with different packing materials obtained from different manufacturers, while the second comprises an octyl-C8 column. The retention indices have been extensively studied using either methanol–water or acetonitrile–water mobile phase systems. The influences of the concentration of the organic modifier in the mobile phase (methanol or acetonitrile), the column temperature, and the column packing material on retention indices of the set of the ten monoaromatics studied were also investigated. The calculated multiparametric retention indices values, those obtained by the local cubic interpolation and Kováts’ methods are compared. Good agreement was observed between the retention indices calculated by the three methods. 相似文献
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《液相色谱法及相关技术杂志》2012,35(6):1133-1150
Abstract Retention indices of some nitrogen-bridged compounds having pharmacological activity have been determined. A retention index scale based on the relative retention of a homologous series of C3-C23 2-keto alkanes has been worked out. Linear relationships were found between RI and logP, allowing a prediction of retention indices. The relationships between the structures and the retention indices of these compounds have been interpreted. 相似文献
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Jamoussi B Kanzari F Ben Hassine B Abderrabba A 《Journal of chromatographic science》2007,45(1):22-27
The retention indices of some polycyclic aromatic hydrocarbons (PAHs) separated by temperature-programmed gas chromatography are computed by smoothing reference data with Bezier curves of orders 6 are more consistent with the scheme of this retention parameter, and they present standard deviations systematically smaller than those associated with classical retention indices. The Bezier curve possesses the property of local control, (i.e., their graphs are modified only in the neighbourhood of the displaced point). The values thus obtained were compared with the corresponding ones calculated in a classical way. Detailed statistical analysis is presented to describe the retention indices of PAHs expressed in the so-called Lee's scale as a function of retention temperatures (in degrees C). As a training set, experimental retention data of PAHs obtained on a PE-5 phase is used for correlation. As prediction sets, literature experimental retention indices expressed in the so-called Lee's scale obtained on a DB-5 slightly polar stationary phase are applied for comparison. The method developed is successfully used for estimating and predicting the capillary gas chromatography retention index of PAHs. 相似文献
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Hassina Larbi Linda Didaoui Michel Righezza 《Journal of the Iranian Chemical Society》2018,15(10):2295-2305
In reversed-phase liquid chromatography (RPLC), the comparison of experimental results obtained from different columns is a complex problem. A correspondence factor analysis (CFA) and a linear solvation energy relationship (LSER) were applied on retention data to characterize second-order intermolecular interactions responsible for retention on a set of RPLC columns. Seven octadecyl-C18 columns with different packing materials are obtained from different manufacturers and one octyl-C8 column. The retention data were determined under isocratic conditions using a methanol–water (65:35, v/v) mobile phase. The chromatographic retention indices based on alkan-2-ones and alkyl aryl ketones retention index scales are calculated using a multiparametric least-squares regressions iterative method. The CFA and LSER results permitted to highlight that the retention indices were appropriate for studying the second-order retention mechanisms on the eight chromatographic systems investigated and exhibited the best reproducibility. Although many earlier studies have reported the use of chemometric methods to characterize chemical factors affecting retention in RPLC using retention factors as retention parameters, this is the first study based on retention indices. 相似文献
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Summary Thermodynamic characteristics determined from retention data measured under isothermal conditions were used for the calculation of retention indices of a number of model compound. The minimum retention index difference required for the identification of two adijacent compounds as well the temperature dependency of retention index are discussed. The possibility of alculating thermodynamic characteristics from retention indices published in the literature was also investigated.Dedicated to Professro J. F. K. Huber on the occasion of his 60th birthday. 相似文献
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