scholarly journals Reversed-phase HPLC retention data in correlation studies with in lipophilicity molecular descriptors of carotenoids

2013 ◽  
Vol 67 (6) ◽  
pp. 933-940 ◽  
Author(s):  
Sanja Podunavac-Kuzmanovic ◽  
Lidija Jevric ◽  
Aleksandra Tepic ◽  
Zdravko Sumic
Keyword(s):  
Predictive Ability ◽  
Reversed Phase ◽  
Retention Mechanism ◽  
Chromatographic Behavior ◽  
Retention Data ◽  
Nonlinear Structure ◽  
Software Products ◽  
Acetone Water ◽  
Paprika Oleoresin ◽  
Predicted Values

Influence of chemical structure on the lipophilicity of isolated free carotenoids from paprika oleoresin has been studied by QSRR approach (Quantitative structure-retention relationship). The chromatographic behavior of these compounds was investigated by using reversed phase high-pressure liquid chromatography (RP HPLC). Retention mechanism has been determined using the following mobile phase: acetone -water, on reversed - phase column (SB-C18). A variety of lipophilicity parameters (logP) were calculated by use of different software products. On the basis of correlations, the nonlinear structure-activity models were derived between the retention constants, tr (retention time of investigation compounds), and logP values. Five high quality QSRR models were found to have a good predictive ability and close agreement between experimental and predicted values. The study showed that the retention constants can be used as a measure of lipophilicity of investigated compounds at a high significant level.

scholarly journals Chromatographic behavior and lipophilicity of s-triazine derivatives on silica gel impregnated with paraffin oil

2010 ◽  
pp. 159-168 ◽  
Author(s):  
Lidija Jevric ◽  
Gordana Koprivica ◽  
Nevena Misljenovic ◽  
Bratislav Jovanovic
Keyword(s):  
Silica Gel ◽  
Volume Fraction ◽  
Reversed Phase ◽  
Retention Mechanism ◽  
Chromatographic Behavior ◽  
Oil Retention ◽  
Paraffin Oil ◽  
Mobile Phases ◽  
Acetone Water ◽  
Triazine Derivatives

The chromatographic behavior of four group of s-triazine derivatives (14 compounds) has been studied by TLC on silica gel impregnated with paraffin oil. Retention mechanism has been determined using the following mobile phases: water-acetone, water-acetonitrile, water-dioxane, water-tetrahydrofuran, water-methanol and water-ethanol, by changing the volume fraction of modifier in the mobile phase. On impregnated silica gel, a reversed-phase chromatographic process occurs. Good correlation was obtained between the retention constants, RM 0 (determined by linear extrapolation), and slope, S, of chromatographic equations. There was also satisfactory correlation between these retention constants and logP values calculated using different theoretical methods. The study showed that the retention constants can be used as a measure of lipophilicity of investigated compounds.

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 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 Estimation of chromatographic lipophilicity of some D-homo androstene derivatives

2015 ◽  
pp. 249-258
Author(s):  
Nada Perisic-Janjic ◽  
Katarina Penov-Gasi ◽  
Evgenija Djurendic ◽  
Marina Savic ◽  
Strahinja Kovacevic ◽  
...  
Keyword(s):  
High Performance ◽  
Predictive Ability ◽  
Reversed Phase ◽  
Chromatographic Retention ◽  
Acetone Water ◽  
Validation Parameters ◽  
Structure Retention ◽  
Leave One Out ◽  
Layer Chromatography ◽  
Quantitative Structure Retention Relationship

Quantitative structure-retention relationship (QSRR) method was applied to study the chromatographic behaviour of D-homo-androstene derivatives 1-7. Retention constants (RM 0) of the analysed derivatives were determined by reversed-phase high-performance thin-layer chromatography (RP HPTLC) on C18 plates by using four mobile phase mixtures: methanol-water, acetone-water, acetonitrile-water, and dioxane-water. Correlation analysis based on multiple regression method was applied in order to model chromatographic retention by means of nine different lipophilicity descriptors (logP). The developed QSRR models were cross-validated and high-quality validation parameters were obtained by leave-one-out method. It was found that the derived QSRR models have a good predictive ability.

scholarly journals Abnormal retention of s-triazine herbicides on porous graphitic carbon

2021 ◽  
Vol 41 (1) ◽  
pp. 1-9
Author(s):  
Oksana Grinevich ◽  
Zoya Khesina ◽  
Alexey Buryak
Keyword(s):  
Stationary Phase ◽  
High Performance ◽  
Reversed Phase ◽  
Retention Mechanism ◽  
Porous Graphitic Carbon ◽  
Graphitic Carbon ◽  
Chromatographic Behavior ◽  
Triazine Herbicides ◽  
Pesticide Monitoring ◽  
Modeling Of Adsorption

Abstract Porous graphitic carbon (PGC) is a widely used stationary phase for reversed-phase high-performance liquid chromatography (HPLC) that allows separation of structurally similar compounds retained in mixed form on a flat graphite surface. Such a stationary phase can be used in analytical chemistry to provide good separation and selectivity in pesticide monitoring. In this article, we studied the chromatographic behavior of five common triazine herbicides (simazine, atrazine, desmetryn, propazine, prometryn) on PGC vis-à-vis octadecyl-functionalized silica gel (ODS). It was found that the herbicides studied have an abnormal elution order on PGC compared to ODS. PGC was also characterized by higher selectivity of analyte separation. This behavior of triazine herbicides on PGC cannot be explained either with the help of existing theory or by mathematical modeling of adsorption processes on graphite. Therefore, we have proposed a possible retention mechanism, explaining the effects observed, due to the shielding of the amino group in the triazine ring by alkyl substituents, which decreases the “polar retention effect” of PGC. Satisfactory separation efficacy was obtained with the proposed analytical method, using convenient UV-detection and without resort to laborious techniques such as HPLC coupled with mass spectrometry.

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 Predicting Pharmacokinetic Properties of Potential Anticancer Agents via Their Chromatographic Behavior on Different Reversed Phase Materials

2021 ◽  
Vol 22 (8) ◽  
pp. 4257
Author(s):  
Małgorzata Janicka ◽  
Anna Mycka ◽  
Małgorzata Sztanke ◽  
Krzysztof Sztanke
Keyword(s):  
Liquid Chromatography ◽  
Anticancer Agents ◽  
Skin Permeation ◽  
Reversed Phase ◽  
Chromatographic Behavior ◽  
Chromatographic Retention ◽  
Quantitative Structure ◽  
Animal Testing ◽  
Structure Activity ◽  
Pharmacokinetic Properties

The Quantitative Structure-Activity Relationship (QSAR) methodology was used to predict biological properties, i.e., the blood–brain distribution (log BB), fraction unbounded in the brain (fu,brain), water-skin permeation (log Kp), binding to human plasma proteins (log Ka,HSA), and intestinal permeability (Caco-2), for three classes of fused azaisocytosine-containing congeners that were considered and tested as promising drug candidates. The compounds were characterized by lipophilic, structural, and electronic descriptors, i.e., chromatographic retention, topological polar surface area, polarizability, and molecular weight. Different reversed-phase liquid chromatography techniques were used to determine the chromatographic lipophilicity of the compounds that were tested, i.e., micellar liquid chromatography (MLC) with the ODS-2 column and polyoxyethylene lauryl ether (Brij 35) as the effluent component, an immobilized artificial membrane (IAM) chromatography with phosphatidylcholine column (IAM.PC.DD2) and chromatography with end-capped octadecylsilyl (ODS) column using aqueous solutions of acetonitrile as the mobile phases. Using multiple linear regression, we derived the statistically significant quantitative structure-activity relationships. All these QSAR equations were validated and were found to be very good. The investigations highlight the significance and possibilities of liquid chromatographic techniques with three different reversed-phase materials and QSARs methods in predicting the pharmacokinetic properties of our important organic compounds and reducing unethical animal testing.

scholarly journals Development and Validation of Retention Models in Supercritical Fluid Chromatography for Impregnation Process Design

2021 ◽  
Vol 11 (15) ◽  
pp. 7106
Author(s):  
Miaotian Sun ◽  
Zeynep Ülker ◽  
Zhixing Chen ◽  
Sivaraman Deeptanshu ◽  
Monika Johannsen ◽  
...  
Keyword(s):  
Supercritical Fluid ◽  
Supercritical Fluid Chromatography ◽  
Stationary Phases ◽  
Retention Factor ◽  
Retention Mechanism ◽  
Retention Data ◽  
Retention Models ◽  
Retention Factors ◽  
Polar Solutes ◽  
Porous Matrices

The retention factor is the key quantity for the thermodynamic analysis of the retention mechanism in chromatographic experiments. In this work, we measure retention factors for moderately polar solutes on four silica-based porous matrices as stationary phases by supercritical fluid chromatography. Elution of the solutes is only possible with binary mixtures of supercritical carbon dioxide (sc-CO2) and modifier (methanol) due to the low polarity of pure sc-CO2. The addition of modifiers makes the retention mechanism more complex and masks interactions between solute and stationary phase. In this work, we develop and validate several retention models that allow the obtaining of retention factors in modifier-free sc-CO2. Such models pave the way for quantifying adsorption interactions between polar solutes and non-swellable porous matrices in pure sc-CO2 based on retention data obtained in sc-CO2/modifier mixtures. The obtained information will thereby facilitate the understanding and design of impregnation processes, which are often performed in modifier-free conditions.

scholarly journals Temperature Effects on Retention and Separation of PAHs in Reversed-Phase Liquid Chromatography Using Columns Packed with Fully Porous and Core-Shell Particles

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Christophe Waterlot ◽  
Anaïs Goulas
Keyword(s):  
Limit Of Detection ◽  
Tap Water ◽  
Reversed Phase ◽  
Chromatographic Behavior ◽  
Core Shell ◽  
Reversed Phase Liquid Chromatography ◽  
Porous Particles ◽  
Phase Liquid ◽  
Effects Of Temperature ◽  
Shell Particles

Effects of temperature on the reversed-phase chromatographic behavior of PAHs were investigated on three columns. The first was the recent C18column (250 mm × 4.6 mm) packed with 5 µm core-shell particles while the others were more conventional C18columns (250 mm × 4.6 mm) packed with fully porous particles. Among the 16 PAHs studied, special attention has been paid to two pairs of PAHs, fluorene/acenaphthene and chrysene/benzo[a]anthracene, which often present coeluting problems. Due to the low surface area of the core-shell particles, lowest retention time of each PAH was highlighted and effects of the temperature on the separation of PAHs were negligible in regard to those using columns packed with fully porous particles. For each PAH studied, it was demonstrated that peaks were symmetrical and may be considered as Gaussian peaks when the column packed with core-shell particle was employed. In the best condition, the separation of PAHs was conducted at 16°C under very low pressure values (670–950 psi = 46–65 bars). Depending on PAHs, the limit of detection ranged from 0.88 to 9.16 μg L−1. Analysis of spiked acetonitrile samples with PAHs at 10 and 50 µg L−1and tap water at 10 µg L−1gave very good recoveries (94%–109.3%) and high precision (1.1%–3.5%).

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