scholarly journals A simple TLC and HPTLC method for separation of selected steroid drugs

2013 ◽  
Vol 11 (8) ◽  
pp. 1297-1308 ◽  
Author(s):  
Joanna Nowakowska ◽  
Piotr Pikul ◽  
Krzesimir Ciura ◽  
Jakub Piotrowicz
Keyword(s):  
Stationary Phase ◽  
Mobile Phase ◽  
Stationary Phases ◽  
Principal Component ◽  
Reversed Phase ◽  
Chromatographic Retention ◽  
Retention Data ◽  
Binary Mobile Phases ◽  
Acetone Water ◽  
Steroid Drugs

AbstractChromatographic properties of five steroid drugs: cortisone, hydrocortisone, methylprednisolone, prednisolone and norgestrel have been studied by normal-, reversed-phase and hydrophilic neutral cyano-bonded silica stationary phase with five binary mobile phases (acetonitrile-water, acetonitrile-DMSO, acetonitrile-methanol, acetone-petroleum ether, acetone-water) in which the concentration of organic modifier was varied from 0 to 100% (v/v). This study reports the optimization of steroid hormones separation. Chromatographic retention data and possible retention mechanisms are discussed. Separation abilities of mobile and stationary phases were studied using the principal component analysis method. The best separation of methylprednisolone and prednisolone is with a chromatographic system included silica gel as stationary phase and mixture of acetonitrile and DMSO (10:90 v/v). These two anti-inflammatory drugs can be fast separated from norgestrel when CN is used as stationary phase and acetone and water (40:60 v/v) as mobile phase. The highest values of the parameter Δ(ΔG°) and alfa for cortisone and hydrocortisone was observed in case of using CN as stationary phase and water-acetonitryle (40:60 v/v) as mobile phase.

scholarly journals Estimation of Solute-Stationary Phase and Solute-Mobile Phase Interactions in the Presence of Ionic Liquids

Separations ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 40
Author(s):  
María José Ruiz-Ángel
Keyword(s):  
Ionic Liquids ◽  
Stationary Phase ◽  
Mobile Phase ◽  
Stationary Phases ◽  
Reversed Phase ◽  
Retention Mechanism ◽  
Chromatographic Behavior ◽  
Chemical Equilibria ◽  
Suppression Effect ◽  
Mobile Phases

The presence of free silanols on alkyl-bonded reversed-phase stationary phases is responsible for broad and asymmetrical peaks when basic drugs are chromatographed with conventional octadecylsilane (C18) columns due to ionic interactions. In the last few years, ionic liquids (ILs) have attracted attention to reduce this undesirable silanol activity. ILs should be considered as dual modifiers (with a cationic and anionic character), which means that both cations and anions are able to adsorb on the stationary phase, creating a positively or negatively charged layer, depending on the relative adsorption. The accessibility of basic compounds to the silanols is prevented by both the IL cation and anion, improving the peak profiles. A comparative study of the performance of six imidazolium-based ILs, differing in their cation/anions, as modifiers of the chromatographic behavior of a group of ten β-adrenoceptor antagonists, is addressed. Mobile phases containing cationic amines (triethylamine and dimethyloctylamine) were used as a reference for the interpretation of the results. Using a mathematical model based on two chemical equilibria, the association constants between the solutes and modified stationary phase as well as those between solutes and the additive in the mobile phase were estimated. These values, together with the changes in retention and peak shape, were used to obtain conclusions about the retention mechanism, changes in the nature of the chromatographic system, and silanol suppression effect.

scholarly journals HPLC FINGERPRINT OF ORGANIC ACIDS IN FRUIT JUICES

1970 ◽  
Vol 62 ◽  
Author(s):  
Loredana Leopold ◽  
Diehl Horst ◽  
Carmen Socaciu
Keyword(s):  
Organic Acids ◽  
Stationary Phase ◽  
Organic Acid ◽  
Mobile Phase ◽  
Reversed Phase ◽  
Fruit Juices ◽  
Hplc Fingerprint ◽  
Organic Acid Profile ◽  
Phase Column ◽  
Reversed Phase Column

Organic acids give fruit products their characteristic tartness and vary in combination and in concentrations among different juices. The organic acid profile can be used to identify a juice or verify its purity. Typically, organic acids in fruit juices are identified and quantified by using methods such as HPLC. In this procedure, reversed phase column is used to separate and identificate six organic acids. Because several of the analytes are extremely difficult to resolve, a aqueous mobile phase is needed to enhance interaction between the acids and the C18 stationary phase.

scholarly journals Reversed-phase thin-layer chromatography behavior of aldopentose derivatives

2012 ◽  
Vol 66 (3) ◽  
pp. 365-372 ◽  
Author(s):  
Dragana Livaja-Popovic ◽  
Eva Loncar ◽  
Lidija Jevric ◽  
Radomir Malbasa
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Stationary Phases ◽  
Reversed Phase ◽  
Chromatographic Behavior ◽  
Log P ◽  
Retention Factors ◽  
Mobile Phases ◽  
Acetone Water ◽  
Layer Chromatography

Quantitative structure-retention relationships (QSRR) have been used to study the chromatographic behavior of some aldopentose. The behavior of aldopentose derivatives was investigated by means of the reversed-phase thin-layer chromatography (RP TLC) on the silica gel impregnated with paraffin oil stationary phases. Binary mixtures of methanol-water, acetone-water and dioxane-water were used as mobile phases. Retention factors, RM0, corresponding to zero percent organic modifier in the aqueous mobile phase was determined. Lipophilicity C0 was calculated as the ratio of the intercept and slope values. There was satisfactory correlation between them and log P values calculated using different theoretical procedures. Some of these correlations offer very good predicting models, which are important for a better understanding of the relationships between chemical structure and retention. The study showed that the hydrophobic parameters RM0 and C0 can be used as a measures of lipophilicity of investigated compounds.

scholarly journals Liquid chromatographic enantioseparation of thalidomide and its derivatives on cyclodextrin-bonded stationary phases

2018 ◽  
Vol 91 (2) ◽  
pp. 99-106
Author(s):  
Szabó-Zoltán István ◽  
Foroughbakhshfasaei Mohammadhassan ◽  
Dobó Máté ◽  
Noszál Béla ◽  
Tóth Gergő
Keyword(s):  
Acetic Acid ◽  
Stationary Phase ◽  
Flow Rate ◽  
Chiral Separation ◽  
Stationary Phases ◽  
Reversed Phase ◽  
Chiral Separations ◽  
Column Temperature ◽  
Bonded Stationary Phases ◽  
Chiral Interactions

Abstract The chiral separation of three racemic immunomodulatory drugs, thalidomide, pomalidomide and lenalidomide was studied, using three cyclodextrin bonded stationary phases (β-, hydroxypropyl-β- and carboxymethyl-β-CD) in reversed-phase and polar organic mode. In polar organic mode, using acetonitrile and methanol, no chiral separation was observed. In reversed-phase mode pomalidomide showed chiral interactions with all selectors, while lenalidomide showed no chiral interactions with any of the cyclodextrins employed. Thalidomide showed chiral interactions with β-and carboxymethyl-β-CD, only. Based on these observations it can be concluded that the oxo group at position two is necessary for chiral recognition, while the aromatic primary amine group enhances it. Orthogonal experimental design was used to investigate the effect of the eluent composition, flow rate, and the column temperature on chiral separation. Concentration of the organic modifier was the most important factor among the investigated three variables showing high impact on the chiral separations. In the case of thalidomide optimized parameters (β-cyclodextrin-based stationary phase, 0.1% acetic acid/acetonitrile 95/5 (v/v), 5 °C column temperature, 0.6 ml/min flow rate) resulted in a resolution of 1.68 ± 0.02 between enantiomers. For pomalidomide, this value was 2.70 ± 0.02, under the circumstances as follows: β-cyclodextrin-based stationary phase, 0.1% acetic acid/acetonitrile 90/10 (v/v), 15 °C column temperature and 0.8 mL/min flow rate. Utilizing the experimental conditions employed on an LC-MS/MS system, concentrations as low as 2 ng/mL could be determined from mouse plasma for both substances. Elution sequences were determined with enantiopure standards and in both cases the R-enantiomers eluted first. The methods developed are suitable for the chiral separation of the abovementioned compounds and are sound starting points for bioanalytical method development.

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