Chromatographic separation map and incremental relationships in the method of relative analysis of retention under HPLC conditions

It was demonstrated that the correlations between the logarithms of the retention factors for various pairs of substances being linear makes it possible to plot and analyze maps of separation of complex mixtures at various mobile phase compositions on the basis of two measurements at the boundaries of the eluent composition range. Applied to the available experimental data, the relative analysis of retention showed that the use of incremental relationships in the form of the difference between the retention parameters for the corresponding substances at a given mobile phase composition is incorrect. A substantiation of the new method was presented.     

Numerical solution of the zero-head seepage problem by discretization of the variational inequality

The problem of zero-head seepage through a cutoff is reduced to solving a variational inequality which is discretized by the finite element method. The discrete variational inequality is solved by a two-layer iterative process. A rate of convergence bound is obtained for the approximate solution and the optimal parameters of the two-layer iterative process are determined. A numerical experiment supports the theoretical results.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 58, pp. 45–56, 1986.     

Relative retention analysis in HPLC: The correlation between incremental relationships

It was shown that, in the absence of specific intramolecular interactions, residual silanol groups of reversed-phase sorbents should not affect the linearity of plots in the coordinates used in the method of relative retention analysis for pairs of substances. The validity of the method proposed previously for analysis of the selectivity of separation of substances was supported experimentally (based on the analysis of retention of substituted benzoates). The possibility of the extension of incremental relationships to the system consisting of three different substances was justified.     

Determination of the triglyceride composition of pomegranate seed oil by reversed-phase HPLC and spectrophotometry

An increment approach and the control of the position of convergence points is proposed for the determination of the fatty acid composition of triacylglycerides (TAGs) from seed oil of pomegranate. reversed-phase HPLC under conditions ensuring the absence of artifacts is shown to distinguish TAGs formed by isomer-conjugated octadecatrienic acids.     

Determination of Anthocyanins by High-Performance Liquid Chromatography: Regularities of Retention

The chromatographic behavior of anthocyanidin derivatives was studied by reversed-phase HPLC. Two types of increment functions in the retention of anthocyanidin glycosides were found. In the first type, an increment corresponding to the replacement of one glycoside with another in a series of different aglycons (as the difference between the logarithms of capacity factors) was independent of the retention of a reference anthocyanin, whereas a linear relationship between the retention parameters was found for the second type.     

Triglyceride Composition Seed Oils from Certain Plants

The type compositions of triglycerides (TAG) from seed oils of various plants were presented. The possibility of using a statistical model to estimate the ratio of TAG types formed by oleic, linoleic, and -linolenic acids was discussed. The greatest deviations from the statistical model were observed in oils for which the TAG contained -linolenic, -eleostearic, and ranunculeic acids.     

Determination of eigenvalues and discontinuous eigenfunctions of the system of equations of elasticity theory

Discretization algorithms are developed for the problem of eigenvalues and discontinuous eigenfunctions of the operator of elasticity theory. The operator is considered in a region with a clamped boundary. Error bounds of the approximate solution are obtained. Model examples are solved.Institute of Cybernetics of the Ukrainian Academy of Sciences. Kiev University. Translated from Vychislitel'naya i Prikladnaya Matematika, No. 74, pp. 38–45, 1992;