Search Results

You are looking at 1 - 8 of 8 items for

  • Author or Editor: Katarzyna Bober x
  • Refine by Access: All Content x
Clear All Modify Search

Fatty acids from pentanoic to tricosanoic have been separated on RP-18 HPTLC plates, with and without concentrating zone, with methanol-water, ethanol-water, and n -propanol-water mobile phases. Separation factors (α), resolution ( R S ), and Δ R F values were calculated for all the chromatograms. Analysis showed that the most useful measures of the quality of the chromatographic separation of these fatty acids were the resolution, R S , and Δ R F . The best chromatographic conditions for separation of the fatty acids were RP-18 plates without concentrating zone and methanol-water, 90 + 10 ( v/v ), methanol-water, 95 + 5 ( v/v ), and ethanol-water, 90 + 10 ( v/v ), as mobile phases, and RP-18 plates with concentrating zone and methanol-water, 90 + 10 and 95 + 5 ( v/v ), 100% methanol, and ethanol-water, 90 + 10 and 95 + 5 ( v/v ), as mobile phases.

Restricted access

Fatty acids from ethanoic to octanoic have been chromatographed on silica gel with n -hexane-acetone, 4 + 1 ( v/v ), and acetone-water-chloroform-ethanol-aqueous ammonia, 30 + 1 + 3 + 5 + 1 ( v/v ), as mobile phases. New visualizing agents and selected visualizing agents described in the scientific literature have been used for detection. The results obtained for the free fatty acids and their ammonium salts by use of the individual visualizing agents depend on method of application — spraying or dipping. Dipping of chromatographic plates into solutions of the visualizing agents leads to chromatographic spots of the fatty acids with better contrast than the spots obtained by direct spraying of the plates. In general better visualization was achieved with ammonium salts of the fatty acids than with the free acids. Of the agents described in the scientific literature free fatty acids from ethanoic to octanoic can be detected only by use of bromocresol green, bromophenol blue, potassium permanganate, and methyl red. Among the new visualizing agents investigated, dipping of chromatographic plates into an aqueous solution of alkaline blue enables detection of the free acids from propanoic to octanoic. The ammonium salts of fatty acids from ethanoic to octanoic can be detected by spraying or dipping using all the visualizing agents investigated except bromophenol blue.

Restricted access

The aim of this work was the application of thin-layer chromatography to the lipophilicity analysis of selected quinobenzothiazine derivatives. These are newly synthesized compounds, which were previously analyzed taking into consideration biological activity and their antiproliferative activity. Experimental lipophilicity parameters (R M0 and log P TLC) were determined by use of thin-layer chromatography, and also some theoretical values of lipophilicity were calculated by use of computer programs. The correlation between the experimental and the theoretical values of lipophilicity was found. Also, cluster analysis was performed for the data obtained. Phenothiazine derivatives were modified mainly by introduction of substituents into the nitrogen atom of the thiazine ring. The computer programs applied based on different theoretical approaches gave different values of lipophilicity parameters depending on the kind of substituent in the quinobenzothiazine system. None of the computer programs took into consideration the influence of substituents in a structure of the tested compounds, and in this case, the calculated lipophilicity parameter had the same value for all isomers with the same substituent. Also, none of the computer programs gave values of lipophilicity parameters close to these obtained by experimental method. The results of log P calc for the compounds 1–13 were quite different according to the computer program used (log P calc = 1.69–5.98). No computer programs gave values of log P calc close to values of log P TLC obtained experimentally. The reason can be the specific special structure of the tested phenothiazine derivatives consisting of tetracyclic system with additional nitrogen atom. It shows that calculation methods can be useless for the preliminary lipophilicity determination of such a kind of compounds.

Restricted access

Methyl laurate, methyl myristate, methyl palmitate, methyl isostearate, methyl stearate, and methyl arachidate have been separated by RPTLC on kieselguhr F 254 impregnated with different amounts of paraffin oil, using two different mobile phases. The R M values of these compounds for all the stationary phases and mobile phases investigated could be correlated with the dipole moments of the mobile phases, with the percentage impregnation of the stationary phase, and with numerical values of one topological index from among those based on the distance matrix ( W , A , ° B , 1 B ) or on the adjacency matrix ( 1 X , 1 X v ). The theoretical partition coefficient (log P ) for methyl isostearate was calculated from R M values or from one of the topological indexes mentioned above.

Restricted access

Fatty acids from pentanoic acid to tricosanoic acid have been separated on RP-18 plates with and without a concentrating zone. Although similar separation factors, α , were obtained for the acids on both types of plate, visual inspection of the chromatograms revealed that better separation of the acids was obtained on RP-18 plates with concentrating zone, because compact chromatographic bands were obtained. The resolution, R S , values calculated confirmed these observations. Topological indexes based on the distance matrix, the adjacency matrix, information theory, and electrotopological states were calculated for the acids. It was found that R M values were related to topological indexes by linear or quadratic functions.

Restricted access

Fatty acids from heptanoic to eicosanoic have been separated on RP-18 HPTLC plates, with and without concentrating zone, with methanol-ethanol-water, methanol- n -propanol-water, and ethanol- n -propanol-water mixtures as mobile phases. The best chromatographic conditions for separation of the fatty acids were RP-18 plates without concentrating zone and methanol-ethanol-water, 45 + 45 + 10 ( v/v as mobile phase, and RP-18 plates with concentrating zone and methanol-ethanol-water or methanol- n -propanol-water, 45 + 45 + 10 ( v/v ), as mobile phases. Taking into consideration previous results of our research we can state that the best RP HPTLC separations of fatty acids have been obtained on RP-18 plates without concentrating zone and with methanol-water, 95 + 5 ( v/v ), as mobile phase, and on RP-18 plates with concentrating zone with methanol-water, 90 + 10 or 95 + 5, 100% methanol, ethanol-water, 95 + 5 or 90 + 10 ( v/v ), or methanol-ethanol-water or methanol- n -propanol-water, 45 + 45 + 10 ( v/v ), as mobile phases. Separation data R S and Δ R F were found most useful for assessing the quality of chromatographic separations of the fatty acids investigated. There is no possibility of separation of acids from methanoic to butanoic and from tetracosanoic to triacontanoic under the chromatographic conditions used.

Restricted access

The aim of the work was the chromatographic separation of salicylic acid and their derivatives, i.e., acetylsalicylic acid, salicylanilide, salicylaldehyde, salicylamide, methyl salicylate, phenyl salicylate, 2,5-dihydroxybenzoic acid, salicylhydroxamic acid, 3,5-dinitrosalicylic acid, 3-aminosalicylic acid, 4-aminosalicylic acid, and 5-aminosalicylic acid by use of adsorption thin-layer chromatography (normal-phase thin-layer chromatography [NPTLC]) and partition thin-layer chromatography (reversed-phase thin-layer chromatography/high-performance thin-layer chromatography [RP-TLC/HPTLC]). Three qualitatively and quantitatively different mobile phases were used for the separation of salicylic acid and its derivatives. Cluster analysis (single linkage method, Euclidean distance) allowed the evaluation of the suitability of the chromatographic conditions used to separate the pairs of tested compounds. The cluster analysis data indicate that the composition of the mobile phase is fundamental in the process of separation of the analyzed compounds by use of NP-TLC. The best separation of the studied substances was observed in the case of mobile phase n-hexane—diethyl ether—acetic acid (80%) in different volume ratios. The similarity analysis of the results obtained by use of RP-TLC/HPTLC revealed that the type of chromatographic plates influences significantly the quality of separation of the tested compounds. The best conditions for the separation by RP-TLC were obtained on silica gel RP-18 F254 plates. The present study indicates that the cluster analysis represents a simple-to-use and powerful chemometric tool in the prediction of TLC separation of medically important salicylic acid derivatives under various chromatographic conditions. It can be helpful in the quality control of multicomponent synthetic preparations containing these compounds or in the chemical standardization of plant products consisting of salicylic acid and related compounds.

Restricted access

Lipophilicity is a very important property while designing new drugs. Its influence on the pharmacological responses of compounds has been known since the 19th century. Also, many researchers try to find the relationships between structure and activity of newly synthetized compounds. The aim of this study was to determine the lipophilicity of 5,8-quinolinedione derivatives using thin-layer chromatography. Moreover, the structure—activity correlation between experimental and theoretical parameters of lipophilicity and anticancer activity was described. A series of 18 compounds was investigated. Experimental lipophilicity was determined by use of reversed-phase thin-layer chromatography (RP-TLC) using RP-18 F254s plates impregnated with silicone oil and the mixture of acetone and water solution of buffer Tris (pH = 7.4) in different volume compositions as mobile phases. Values of calculated lipophilicity (ALOGPs, AClogP, miLogP, KOWWIN, XLOGP2, MLogP, ABlogP, and ACD/LogP) were taken from the internet database. The correlation between experimental and calculated values of lipophilicity was found. For some compounds investigated, the calculated values of lipophilicity were relatively high. The correlation coefficient for these relationships was not very high but statistically significant. It confirms that the structure of compounds investigated affects the value of lipophilicity. The correlation between lipophilicity and anticancer activity was also determined, but unfortunately, no correlation was found. Additionally, similarity analysis was prepared for compounds investigated and results of lipophilicity were obtained.

Restricted access