Wyniki wyszukiwania - BazTech

1

RP-HPTLC determination of the lipophilicity of some new derivatives of thiosemicarbazide and 1,2,4-triazole of sulphanylacetic acid

Hawrył A., Popiołek Ł, Dobosz M., Pikuła E, Waksmundzka-Hajnos M.

Acta Chromatographica

|

2010

|

Vol. 22, no. 1

37--55

EN

Some new derivatives of thiosemicarbazide and the 1,2,4-triazole of sulphanylacetic acid have been chromatographed on RP-18 HPTLC plates with mobile phases containing water and an organic modifier (methanol, dioxane, acetone, 2-propanol, or tetrahydrofuran). Relationships between solute retention and modifier concentration were described by Snyder’s linear equation. The equation was used to determine R M 0 values, by extrapolation, and the S values denoting the slopes of the relationship between linear retention and mobile phase concentration; both values characterize the lipophilicity of the substances. Calculated values of R M 0 were correlated with log P values for the drugs investigated by use of the software HyperChem. Correlations between intercept ( R M 0 ) and slope ( S ) from the linear equations were also calculated. The effects of different mobile phase modifiers on experimentally obtained lipophilicity were also analysed and compared.

2

Reversed-phase TLC study of the lipophilicity of some 3-hydroxy-1,2-benzisoxazoles substituted in the benzene ring

Sławik T., Skibiński R., Paw B., Działo G

Acta Chromatographica

|

2009

|

Vol. 21, no. 2

251--258

EN

The relative lipophilicity, R M0 , and specific hydrophobic surface area of eleven 3-hydroxy-1,2-benzoisoxazoles substituted in the benzene ring (two isomeric fluoro, three isomeric chloro, three isomeric bromo and dibromo derivatives, and a nitro derivative) have been studied by reversed-phase thin layer chromatography (RP-TLC) on silica gel RP-C18 plates with methanol-water mixtures as mobile phases. Linear correlation between the volume fraction of methanol and R M values over a limited range was established with high correlation coefficients ( r > 0.99). Lipophilicity R M0 was compared with computed partition coefficients IAlogP, A logP s , clogP, milogP, logP KOWIN , and xlogP. The best correlation ( r > 0.9) was found between R M0 and logP KOWIN and xlogP values. Principal-components analysis (PCA) was also used to compare R M0 values with computed partition coefficients. The chromatographic behaviour of 3-hydroxy-1,2-benzisoxazoles was compared with that of their bioisosteric analogues 1,2-benzisot-iazolonoles. Experimental R M0 values for both groups of compounds were in accor-dance with the equation R M0 aR M0 +b(r> 0.9).

3

Determination of the lipophilicity of new azaphenothiazines by reversed-phase thin-layer chromatography

Zięba A., Prus W.

Acta Chromatographica

|

2009

|

Vol. 21, no. 3

369--378

EN

The lipophilicity R M0 and log P TLC of thirteen novel, potentially biologically active, 12 H -quino[3,4- b] [1,4] benzothiazinium salts have been determined by reversed-phase thin-layer chromatography using RP-18 silica plates and methanol-aqueous Tris buffer solution mixtures as mobile phases. R M values of the compounds were linearly dependent on methanol concentration; extrapolation of these to 0% methanol gave the lipophilicity R M0 . log P TLC was obtained from R M0 by use of a calibration curve obtained for five standards of known experimental lipophilicity (log P). Lipophilicity log P calcd for the thirteen quinobenzothiazines was calculated by use of nine software products. The values determined were discussed in terms of structure-lipophilicity relationships. The results indicate that chromatographic lipophilicity R M0 can be used as a measure of the lipophilicity of the azaphenothiazine derivatives investigated.

4

Determination of the lipophilicity of selected isoquinoline alkaloids by RP-TLC

Waksmundzka-Hajnos M., Matosiuk D., Petruczynik A., Kijkowska-Murak U.

Acta Chromatographica

|

2008

|

Vol. 20, no. 4

563-573

EN

Nine alkaloids were chromatographed by reversed phase (RP) TLC on RP-18 with aqueous acetone or aqueous dioxane mobile phases. A variety of mobile phase additives (ammonia, diethylamine (DEA), tetrabutylammonium chloride (TBA-Cl)) were used to suppress ionization of the alkaloids and/or reduce ionic interactions with surface silanol groups. Ion-pair (IP) RP-TLC was also performed with aqueous acetone mobile phases and reagents such as pentane sulphonic acid (PSA), octane sulphonic acid (OSA), or di-(2-ethylhexyl)orthophosphoric acid (HDEHP) as mobile phase additives. In these systems retention of the alkaloids was determined using mobile phases with different modifier concentrations. Relationships between R M and modifier concentration were sought. A linear semilogarithmic equation was fitted to experimental data and used to obtain lipophilicity values R MW ( R M for pure water), the slope ( S ), and φ 0 , the intercept with the x -axis. The retention of standards with known lipophilicity log P was then determined using the chromatographic systems described above and R MW values were calculated. From these experimental data equations relating log P and R MW were created for each system separately and these equations were used to estimate log P exp values for the alkaloids. log P exp , slope ( S ), and φ 0 values obtained by use of different TLC systems were also correlated.

5

RP-HPLC and RP-TLC in the analysis of flavonoids

Baranowski R., Kabut J., Baranowska I.

Chemia Analityczna

|

2005

|

Vol. 50, No. 1

301-313

EN

Effect of mobile phase composition on the separation of flavonoids from five major classes (catechins, flavonols, flavanones, flavones and anthocyam'dins) has been investigated on RP-18 TLC plates. Water-acetonitrile mixtures and trifl no ro acetic acid in waier-acetoni-trile mixtures have been used as the mobile phases. An RP-HPLC system for these compounds has also been developed. Interferences from vitamins and methyixanthines in the new RP-HPLC system have been investigated. Flavonoids were determined in fruit, vegetables, wine, tea and urine samples.

PL

Rozdzielano flawonoidy z pięciu gtównych klas (katechiny, flawony. flawanony, flawonole i antocyjanidyny) metodą chromatografii cienkowarstwowej na płytkach RP-18, stosując jako fazę ruchomąmieszaniny wody i acetonitrylu z dodatkiem kwasu trifluorooctowego. Dla tej samej grupy flawonoidów opracowano układ RP-HPLC. W opracowanym układzie badano wpływ interferencji ze strony witamin i metyłoksantyn. Oznaczono zawartość flawonoidów w próbkach: owoców, warzyw, win, herbat i w moczu.