Liquid chromatography with a dynamic temperature gradient

Abstract

The theoretical principles of chromatography using a dynamic temperature gradient are described in terms of aspects of liquid-solid systems. Along the chromatographic column, an oven moves in the direction of flow of the mobile phase and thus creates a temperature gradient on the column, the temperature of which decreases in the direction of flow of the mobile phase. Each component of the mixture under analysis has a characteristic temperature in the gradient at which it is eluted from the column. The use of the dynamic temperature gradient has some advantages similar to those for the technique using a concentration gradient of the mobile phase (reduction in the time of analysis, linearization of the sorption isotherms, etc.). However, some additional advantages were found that can be used particularly in high-efficiency liquid chromatography. The composition of the mobile phase does not change and therefore the response of the detector can be used for the quantitative evaluation of the chromatogram. The column has the same adsorption properties after the analysis as before the application of the dynamic temperature gradient. An increase in the number of effective plates per second and in the peak capacity of the column were found, simultaneous with a decrease in the capacity ratio. The method can also be used for the enrichment of samples containing trace amounts of admixtures.