scholarly journals Retention behaviour of some estradiol derivatives on alumina in normal phase chromatrography

2003 ◽  
Vol 68 (3) ◽  
pp. 163-170 ◽  
Author(s):  
Marijana Acanski
Keyword(s):  
Mobile Phase ◽  
Volume Fraction ◽  
Retention Behavior ◽  
Relative Retention ◽  
Linear Relationships ◽  
Mobile Phases ◽  
Binary Mobile Phases ◽  
Estradiol Derivatives ◽  
Rf Values ◽  
The Relationship

The retention constants of variously substituted estradiol derivatives were measured as a function of the composition of various binary mobile phases in order to study the relationship between chemical structure and retention behavior in TLC on alumina. The slopes and intercepts of the linear relationships between the retention constant RM and the logarithm of the volume fraction of the polar mobile phase component were calculated and are discussed in relation to the characteristics of the solute and mobile phase. The RF values and relative retention ?RM of the compounds depend largely on the retention behavior of their substituents. The results obtained in this investigation are compared with the results of the same derivatives obtained in previous investigations on silica gel.

scholarly journals Normal-phase high performance liquid chromatography of estradiol derivatives on amino- and diol-columns

2003 ◽  
Vol 68 (12) ◽  
pp. 971-977
Author(s):  
Marijana Acanski
Keyword(s):  
High Performance Liquid Chromatography ◽  
Mobile Phase ◽  
High Performance ◽  
Volume Fraction ◽  
Stationary Phases ◽  
Normal Phase ◽  
Retention Behavior ◽  
Estradiol Derivatives ◽  
Binary Mobile Phase ◽  
The Relationship

The retention behavior of estradiol derivatives was studied by HPLC on chemically bonded polar stationary phases: commercially available amino and diol- columns, as a function of the heptane-propan-1-ol as the mobile phase, when the volume fraction of propan-1-ol in the binary mobile phase was low, even less than 5 %. The relationship between the logarithm of the retention constant (log k) and the logarithm of the volume fraction of propan-1-ol (?log ?) in the eluent was linear for all solutes studied. The results are discussed in terms of the solute and stationary phase properties and compared with the results of the same derivatives obtained in earlier investigations.

scholarly journals Retention behaviour of acyclic polyfunctional D-arabinose derivatives

2002 ◽  
pp. 35-44 ◽  
Author(s):  
Ljiljana Kolarov ◽  
Eva Loncar ◽  
Radomir Malbasa
Keyword(s):  
Mobile Phase ◽  
Volume Fraction ◽  
Retention Mechanism ◽  
Biologically Active ◽  
Polar Component ◽  
Chiral Molecules ◽  
Retention Behaviour ◽  
Polar Components ◽  
Solute Retention ◽  
Mobile Phases

It is well known that some of biologically active compounds are chiral molecules. Natural monosaccarides are applicable as chiral precursors. D-arabinose is an appropriate chiral precursor in the synthesis of very important biomolecules such as biotin and its analogues and feromon )-exobrevicomin. Acyclic poly functional D- arabinose derivatives are intermediates in the synthesis of the former biomolecules. This paper deals with the retention behaviour and retention mechanism of acyclic poly functional D-arabinose derivatives. The tested compounds have been chromato graphed on silica gel thin layer using binary organic mobile phases with a different polarity. With increasing polarity of the eluent polar components the solute retention is decreasing. The linear relationship is obtained between the values of retention constant, RM' and the logarithm of the mobile phase polar component volume fraction for all solutes tested and eluents used.

scholarly journals Retention behaviour of estradiol derivatives in reversed phase HPLC

2005 ◽  
pp. 169-178
Author(s):  
Marijana Acanski ◽  
Slobodan Petrovic
Keyword(s):  
Linear Relationship ◽  
Silica Gel ◽  
Mobile Phase ◽  
Volume Fraction ◽  
Reversed Phase ◽  
Considerable Effect ◽  
Reversed Phase Hplc ◽  
Retention Behaviour ◽  
Estradiol Derivatives ◽  
Octadecyl Silica Gel

Retention behaviour ofestradiol derivatives has been studied by the reversed phase HPLC. LiChrosorb RP-18 column end eluents consisting of methanol respectively aceto-nitrile and water in various proportions, were used. It was shown that there is a linear relationship between the retention constant and the volume fraction of organic component in the mobile phase. The slopes and intercepts of lines are in agreement with the polarity of derivatives studied. Considerable effect on the chromatographic behaviour exerted the type and position of substituents in the molecule of estradiol derivative. Results obtained in these investigations are compared with results of the same derivatives obtained in previous investigations on octadecyl silica gel in TLC with eluent methanol-water in various proportions.

scholarly journals HPTLC Fingerprint Analysis of Naregamia alata W and A- A Medicinal Plant

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Vinny K. V. ◽  
Prameela T. S. ◽  
Oommen P. Saj
Keyword(s):  
Medicinal Plant ◽  
Mobile Phase ◽  
Methanol Extract ◽  
Phase 2 ◽  
Fingerprint Analysis ◽  
Phase 3 ◽  
Mobile Phases ◽  
Finger Printing ◽  
Rf Values ◽  
Selection Of

Aim of this study was to develop a HPTLC fingerprint profiles for various secondary metabolites of methanol extract of the root of the traditional medicinal plant, Naregamia alata. CAMAG HPTLC system equipped with Linomat V applicator, TLC scanner 3, Reprostar 3 and WIN CATS-4 software were used. HPTLC finger printing of methanol extract of root carried out in three different mobile phases, which showed different Rf values. HPTLC finger printing of methanol extract of root in Mobile phase1 revealed 10 peaks with Rf values in the range of 0.13 to 0.92, Mobile phase 2 showed 7 peaks with Rf values in the range of 0.27 to 0.93 and Mobile phase 3 revealed 4 peaks with Rf values in the range of 0.25 to 0.78. It can be concluded that different Rf values of various phytochemicals provide valuable idea regarding their polarity and selection of solvents for separation of phytochemicals. This study will help in future for identifying this plant for further research.

scholarly journals Relationships Between LC Retention, Octanol–Water Partition Coefficient, and Fungistatic Properties of 2-(2,4-Dihydroxyphenyl)benzothiazoles

2004 ◽  
Vol 87 (3) ◽  
pp. 579-586 ◽  
Author(s):  
Joanna Matysiak ◽  
Andrzej Niewiadomy ◽  
Bogdan Senczyna ◽  
Anna Żabińska ◽  
Jan K Rózyło
Keyword(s):  
Mobile Phase ◽  
High Performance ◽  
Hydrophobic Surface ◽  
Quantitative Structure Activity Relationship ◽  
Log P ◽  
Retention Behavior ◽  
Hydrophobicity Index ◽  
Mobile Phases ◽  
Chromatographic Parameters ◽  
Mic Minimum Inhibitory Concentration

Abstract The retention behavior of newly synthesized compounds with antimycotic activity from the 2-(2,4-dihydroxyphenyl)benzothiazole group by high-performance liquid chromatography has been investigated. RP-18 stationary phase and methanol–acetate buffer aqueous mobile phases at pH 4 and 7.4 have been used. In the case of the mobile phase at pH 7.4, higher concentrations of water can be applied than at pH 4. The studied compounds showed regular retention behavior, their log k values decreasing linearly with an increasing concentration of methanol in the mobile phase. On the basis of these relationships, the lipophilicity (log kw), specific hydrophobic surface area (S), and isocratic chromatographic hydrophobicity index (φ0) were determined. Similar log kw values and sensitivity to changes in the structure of compounds studied for both mobile phases have been found. Moderate correlations between the chromatographic parameters and the calculated octanol-water log P values were found. Finally, the lipophilicity parameters were compared with the fungistatic properties of compounds expressed by log MIC (minimum inhibitory concentration) values to find quantitative structure activity relationship equations.

Reverse Phase Thin Layer Chromatography of Some Aroclors, Halowaxes, and Pesticides

1973 ◽  
Vol 56 (2) ◽  
pp. 367-372
Author(s):  
David L Stalling ◽  
James N Huckins
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Mobile Phase ◽  
Gas Liquid Chromatography ◽  
Chlorinated Pesticides ◽  
Reverse Phase ◽  
Mobile Phases ◽  
Rf Values ◽  
Solvent Systems ◽  
Layer Chromatography

Abstract The components of Aroclors® 1232, 1248, 1254, and 1260; Halowaxes® 1099, 1013, and 1014; and several chlorinated pesticides are resolved by reverse phase thin layer chromatography (RPTLC), which permits component separation by partition between a nonpolar stationary phase and a polar mobile phase. Rf values of resulting spots were calculated for 2 of 4 new solvent systems (mobile phases). RPTLC patterns were reproducible and characteristic of each material examined. The spots were recovered from the plates and characterized by gas-liquid chromatography (GLC) and/or GLC-mass spectrometry. In some cases, single GLC peaks of Aroclor standards were resolved into more than one component by RPTLC, whereas some RPTLC spots of Halowaxes were resolved into as many as 4 GLC peaks. The analysis of environmental residues of chlorinated compounds was facilitated by this technique.

scholarly journals Lack of an association between gallstone disease and bilirubin levels with risk of colorectal cancer: a Mendelian randomisation analysis

2021 ◽  
Author(s):  
Richard Culliford ◽  
Alex J. Cornish ◽  
Philip J. Law ◽  
Susan M. Farrington ◽  
Kimmo Palin ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Large Scale ◽  
Causal Effect ◽  
Gallstone Disease ◽  
Epidemiological Studies ◽  
Mendelian Randomisation ◽  
Linear Relationships ◽  
Potential Risk Factors ◽  
The Relationship ◽  
Circulating Levels

Abstract Background Epidemiological studies of the relationship between gallstone disease and circulating levels of bilirubin with risk of developing colorectal cancer (CRC) have been inconsistent. To address possible confounding and reverse causation, we examine the relationship between these potential risk factors and CRC using Mendelian randomisation (MR). Methods We used two-sample MR to examine the relationship between genetic liability to gallstone disease and circulating levels of bilirubin with CRC in 26,397 patients and 41,481 controls. We calculated the odds ratio per genetically predicted SD unit increase in log bilirubin levels (ORSD) for CRC and tested for a non-zero causal effect of gallstones on CRC. Sensitivity analysis was applied to identify violations of estimator assumptions. Results No association between either gallstone disease (P value = 0.60) or circulating levels of bilirubin (ORSD = 1.00, 95% confidence interval (CI) = 0.96–1.03, P value = 0.90) with CRC was shown. Conclusions Despite the large scale of this study, we found no evidence for a causal relationship between either circulating levels of bilirubin or gallstone disease with risk of developing CRC. While the magnitude of effect suggested by some observational studies can confidently be excluded, we cannot exclude the possibility of smaller effect sizes and non-linear relationships.

scholarly journals Differential Influence of Age on the Relationship between Genetic Mismatch and A(H1N1)pdm09 Vaccine Effectiveness

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 619
Author(s):  
Lirong Cao ◽  
Shi Zhao ◽  
Jingzhi Lou ◽  
Hong Zheng ◽  
Renee W. Y. Chan ◽  
...  
Keyword(s):  
Age Groups ◽  
The Elderly ◽  
Vaccine Effectiveness ◽  
Amino Acid Mutation ◽  
Epidemic Season ◽  
Vaccine Component ◽  
Linear Relationships ◽  
The Difference ◽  
Middle Aged Adults ◽  
The Relationship

Assessment of influenza vaccine effectiveness (VE) and identification of relevant influencing factors are the current priorities for optimizing vaccines to reduce the impacts of influenza. To date, how the difference between epidemic strains and vaccine strains at genetic scale affects age-specific vaccine performance remains ambiguous. This study investigated the association between genetic mismatch on hemagglutinin and neuraminidase genes and A(H1N1)pdm09 VE in different age groups with a novel computational approach. We found significant linear relationships between VE and genetic mismatch in children, young adults, and middle-aged adults. In the children’s group, each 3-key amino acid mutation was associated with an average of 10% decrease in vaccine effectiveness in a given epidemic season, and genetic mismatch exerted no influence on VE for the elderly group. We demonstrated that present vaccines were most effective for children, while protection for the elderly was reduced and indifferent to vaccine component updates. Modeling such relationships is practical to inform timely evaluation of VE in different groups of populations during mass vaccination and may inform age-specific vaccination regimens.

Estimation of Interlayer Thickness in Inorganic Particulate-Filled Polymer Composites

2011 ◽  
Vol 24 (6) ◽  
pp. 777-788 ◽  
Author(s):  
J.Z. Liang
Keyword(s):  
Polymer Composites ◽  
Volume Fraction ◽  
Particle Diameter ◽  
Interfacial Structure ◽  
Interlayer Thickness ◽  
Filled Polymer ◽  
Mechanical And Physical Properties ◽  
The Relationship ◽  
Good Agreement

The structure of the interlayer between matrix and inclusions affect directly the mechanical and physical properties of inorganic particulate-filled polymer composites. The interlayer thickness is an important parameter for characterization of the interfacial structure. The effects of the interlayer between the filler particles and matrix on the mechanical properties of polymer composites were analyzed in this article. On the basis of a simplified model of interlayer, an expression for estimating the interlayer thickness ([Formula: see text]) was proposed. In addition, the relationship between the [Formula: see text] and the particle size and its concentration was discussed. The results showed that the calculations of the [Formula: see text] and thickness/particle diameter ratio ([Formula: see text]) increased nonlinearly with an increase of the volume fraction of the inclusions. Moreover, the predictions of [Formula: see text] and the relevant data reported in literature were compared, and good agreement was found between them.

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