Free energies of amino acid adsorption on silica in neutral aqueous medium as estimated from high-performance liquid-chromatographic retention data

Amino Acids ◽  
1994 ◽  
Vol 7 (3) ◽  
pp. 305-309 ◽  
Author(s):  
V. A. Basiuk ◽  
T. Yu. Gromovoy
Keyword(s):  
Amino Acid ◽  
Aqueous Medium ◽  
High Performance ◽  
High Performance Liquid Chromatographic ◽  
Chromatographic Retention ◽  
Retention Data ◽  
Free Energies ◽  
Neutral Aqueous Medium ◽  
Liquid Chromatographic

Free Energies of Adsorption of Dipeptides and 2,5-Piperazinediones on Silica from Neutral Aqueous Solutions as Estimated from High-Performance Liquid-Chromatographic Retention Data

1994 ◽  
Vol 59 (8) ◽  
pp. 1721-1728 ◽  
Author(s):  
Vladimir A. Basiuk ◽  
Taras Yu. Gromovoy
Keyword(s):  
Aqueous Solutions ◽  
High Performance ◽  
Equilibrium Constants ◽  
High Performance Liquid Chromatographic ◽  
Chromatographic Retention ◽  
Retention Data ◽  
Free Energies ◽  
Sorbate Molecule ◽  
Aliphatic Carbon ◽  
Liquid Chromatographic

The equilibrium constants (K) and free energies (-∆G) of adsorption of dipeptides and their cyclic derivatives, 2,5-piperazinediones, on silica from neutral aqueous solutions were calculated from their HPLC retention data on a silica gel column. For the majority of the dipeptides -∆G values were negative, ranging from -1 170 to 430 J mol-1, and K < 1, thus indicating a very weak adsorption. The 2,5-piperazinediones under study exhibited higher adsorbabilities (-∆G -1 070 + 3 030 J mol-1, K > 1) as compared to the respective dipeptides. The effect of the α-substituent structure on the adsorbability is analyzed. A linear dependence of -∆G on the number of aliphatic carbon atoms in a sorbate molecule was observed for the series of dipeptides and 2,5-piperazinediones derived from bifunctional aliphatic amino acids.

QSPR Prediction of Retention Times of Methylxanthines and Cotinine by Bioplastic Evolution

2018 ◽  
Vol 3 (1) ◽  
pp. 74-87 ◽  
Author(s):  
Francisco Torrens ◽  
Gloria Castellano
Keyword(s):  
High Performance ◽  
Formation Enthalpy ◽  
Fractal Dimensions ◽  
High Performance Liquid Chromatographic ◽  
Chromatographic Retention ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Prediction Of Retention ◽  
Acquired Characters ◽  
Liquid Chromatographic

High-performance liquid-chromatographic retention times of methylxanthines and cotinine in human plasma and urine are modelled by structure–property relationships. Bioplastic evolution is an evolutionary perspective conjugating the effect of acquired characters, and relations that emerge among the principles of evolutionary indeterminacy, morphological determination and natural selection. It is applied to design co-ordination index, which is used to characterize retentions of methylxanthines, etc. Parameters used to calculate co-ordination index are formation enthalpy, molecular weight and surface area. Morphological and co-ordination indices provide strong correlations. Effect of different types of features like thermodynamic, fractal, etc., are analyzed. The molar formation enthalpy, fractal dimensions, etc. distinguished methylxanthines and cotinine in linear fits. Different behaviour depends on number of C+N+O atoms.

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