No abstract

No abstract

No abstract

No abstract

Journal of Liquid ChromatographyPublication details, including instructions for authors and subscription information: ABSTRACT I n this study, the retention mechanisms on the Supelcosil LC-ABZ stationary phase were analyzed by linear solvation free-energy relationships (LSERs). In a first phase, a set of 60 compounds was selected by cluster analysis from a large set (253) compounds of known van der Waals volume (Vw), polarity/polarizability (II"), H-bond donating acidity (a) and H-bond acceptor basicity (p). The capacity factors log k at 40% methanol and the log k , values were shown to be highly correlated with octanoYwater partition coefficients (log Pact) andto contain pratically the same structural information, as assessed byLSERs. Test sets of model compounds and dipeptides were used to 1721 Copyright @ 1995 by Marcel Dekker, Inc. Downloaded by [Michigan State University] at 16:34 09 January 2015 1722 PAGLIARA ET AL.validate the log kw/log P and log k/log P relations. For anions and zwitterions, specific interactions with the stationary phase occur which produce systematic deviations in the log k/log P relations.

No abstract

No abstract

ABSTRACT:The corrosion inhibition of steel in phosphoric acid by thiosemicarbazide derivatives has been studied using different chemical and electrochemical techniques. The observed order of increasing inhibition efficiency was correlated with changes in the molecular structures of the inhibitors. Potentiodynamic polarization curves indicate that the compounds are mixed-type inhibitors. Electrochemical impedance spectroscopy has been used successfully to evaluate the performance of the inhibitors. AC measurements showed that the dissolution process was activation-controlled. The kinetic-thermodynamic model and the Flory-Huggins adsorption isotherm described the experimental findings well. The number of active sites, binding constant and change in free energy were computed for all the inhibitors studied. It was found that the inhibitor molecule was adsorbed through more than one active centre and occupied more than one active site on the steel surface.