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1

Peptide mapping by high-performance liquid chromatography

Skrzydlewska E., Ostrowska J., Figaszewski Z.

Acta Chromatographica

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1998

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No. 8

70-84

EN

The determination of protein structure by peptide mapping is described in this paper. The method consists in selective fragmentation of the protein molecule with trypsin, separation of resulting peptides by HPLC, and amino acid analysis. Gradient reversed-phase HPLC is performed with 0.1% TFA in water and 0.1% TFA in acetonitrile as mobile phases.

2

Modelling of solute retention in normal-phase HPLC with the chemically bonded 3-cyanopropyl stationary phase

Prus W., Vander Heyden Y., Massart D. L., Kowalska T.

Acta Chromatographica

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1998

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No. 8

98-108

EN

We have investigated the applicability of two models of solute retention (i.e. Models I and II, devised by Kowalska for liquid chromato-graphy with alcohol-hydrocarbon mobile phases) for description of the chromatographic behavior of 25 test solutes in normal-phase (NP) HPLC systems with the 3-cyanopropyl stationary phase and 2-propanol-n-hexane as mobile phase. The test solutes employed were from five chemical classes, (i) an alkylbenzene, (ii) crown ethers, (iii) hydroxyaromatic and methylhydroxyaromatic compounds, (iv) naphthylamines and (v) quino-line and its derivatives, and thus differed considerably in molecular structure, and hence in their ability to compete with 2-propanol molecules for active sites (i.e. the -CN and ≡Si-OH groups) of the stationary phase, which is the quintessence of the so-called displacement mechanism of solute retention. The performance of Models I and II was evaluated in terms of the numerical values of the root-mean-squared error (RMSt), calculated for each employed test solute and our investigations showed that Models I and II are very well suited for description of the chromato-graphic behavior of solutes for which there is a non-linear empirical relationship between retention parameter (RF or lnk) and the composition of a binary mobile phase.

3

High-performance liquid chromatographic determination of 4,6-dinitro-2-isopropylphenol in workplace air

Politowicz M., Pośniak M.

Acta Chromatographica

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1998

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No. 8

113-121

EN

The optimum conditions have been determined for high-perfor-mance liquid chromatographic (HPLC) analysis of 4,6-dinitro-2-isopro-pylphenol (DNPP) vapour and aerosol in workplace air; the conditions investigated were not only those used for chromatography, but also those enabling representative sampling of air, full separation of the tested compound, and the determination of desorption coefficient. For DNPP concentrations from 0.0125 to 0.15 mg m-3 the calibration plot can be represented by a straight line. The coefficient of desorption was found to be 93%.

4

Chemometric analysis of retention data from high-performance liquid chromatography - structural parameters and biological activity of sulphonamides

Bober L., Nasal A., Kuchta A., Kaliszan R.

Acta Chromatographica

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1998

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No. 8

48-69

EN

High-performance liquid chromatographic (HPLC) retention data measured for 12 sulphonamides on Nucleosil 100-5-C18 octadecylsilica, Spherisorb S5-C1 trimethylsilane-bonded silica and Spheri-10 Anion AX-MP have been analysed. Multivariate analysis was used for quantitative correlation of the capacity factors of the solutes with structural information extracted from 48 molecular descriptors, including UV-spectroscopic parameters, quantum chemical indices, calculated log P, molar refractivity, magnetic susceptibility, electronegativity, a parameter reflecting electron donor-acceptor properties of the solutes, pKa and information-content indices. The first two principal components obtained by factor analysis of 28 descriptors of the highest statistical significance seemed meaningful for the description of retention. Most important for retention on the stationary phases tested were structural parameters reflecting the capacity of solutes to participate in non-specific (dispersive) intermolecular interactions. The distribution of individual drugs on the plane determined by the first two factor axes produced patterns in good agreement with the established classification of sulphonamides according to their pharmacokinetic properties. Multivariate analysis of structural descriptors was shown to furnish systematic information about the drugs; this information was useful both for explaining the mechanism of separation and predicting the pharmacokinetic properties of the sulphonamides.