0000000000371391
AUTHOR
Juris P. Kreišmanis
Liquid chromatography and characterization of ether-functionalized imidazolium ionic liquids on mixed-mode reversed-phase/cation exchange stationary phase
Abstract A new series [CnOmmim]Cl of imidazolium cation-based ionic liquids (ILs), with an ether functional group on the alkyl side-chain, has been prepared. The possibility of analyzing the ionic liquids by high performance liquid chromatography (HPLC) was investigated on mixed-mode reversed/cation exchange stationary phase with the aqueous-acetonitrile mobile phase. Elution parameters, such as retention factor, selectivity and column efficiency, were studied as functions of mobile phase composition and pH. The ILs were characterized by elemental analysis, and infrared, UV and 1H, 13C NMR spectroscopy.
Hydration and dehydration kinetics of xylazine hydrochloride
From the experiments where mixture of xylazine hydrochloride hydrate H and anhydrous X were held at constant conditions, the stable form of xylazine hydrochloride can be found out. To determine equilibrium relative humidity, the unstable form of xylazine hydrochloride was inserted in thermostated humidity chamber and its weight was recorded by weighing the sample outside the chamber. The kinetic model and the rate constant for each condition were determined. The rate constants give information regarding the speed of the process at every experimentally used relative humidity. Thus using the data in coordinates k – p for each temperature it is possible to determine the water vapor pressure of…
The relative stability of xylazine hydrochloride polymorphous forms
All four known xylazine hydrochloride polymorphous forms were obtained and their relative stabilities were compared directly at three different temperatures. At higher temperatures, it is possible to determine the relative stability of all forms directly by measuring the changes in the composition of the mixtures of two polymorphous forms using powder x-ray diffraction methods. At lower temperatures, a solvent was added to the mixture and the changes in composition were determined. Polymorph transition temperatures were determined directly. To predict the transition temperature which was not found using the direct method, the polymorph melting data and determined transition temperatures wer…