Determination of thermodynamic parameters of morpholinium 2-(5-(pyridinyl)-1,2,4-triazole-3-ylthio)acetate and its impurities in conditions of reverse phase chromatography

Abstract

The study of thermodynamic retention parameters helps to optimize the separation process in chromatography, and it is also possible to detrmine the nature of the interaction of analyts with the stationary phase. The aim of the work - study the dependence of the capacity factor on temperature for 5-(pyridinyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione, morpholinium 2-(5-(pyridin-4-yl)-1,2,4-triazole-3-ylthio)acetate and calculation of enthalpy of transfer of substances from mobile to stationary phase. Materials and methods. High performance liquid chromatographic system Agilent 1260 Infinity. Substances 5-(pyridinyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione, morpholinium 2-(5-(pyridinyl)-1,2,4-triazole-3-ylthio)acetate. Zorbax SB-C18 column; 30 mm × 4.6 mm; 1.8 μm. The column temperature was 40 °C. The mobile phase consisted of water (0.1% HCOOH) and acetonitrile (0.1% HCOOH) (95: 5). Results. The retention time values for substances at temperatures from 30 to 70 °C were determined and used to calculate the capacity factors k. The least squares method was used to calculate the equation of the linear dependence of lnk on 1/T. The enthalpies of transfer of substances were calculated according to the Vant-Goff equation. Conclusions. Standard enthalpies of transfer of analytes from mobile phase to stationary phase for 5-(pyridinyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione, morpholinium 2-(5-(pyridin-4-yl))-1,2,4-triazole-3-ylthio)acetate. We observe that the test compounds have a negative value of the enthalpy of transfer. This shows the predominant transition of substances from the mobile phase to the stationary one.

Keywords

• enthalpy
• high performance liquid chromatography
• active pharmaceutical ingredients