RESUMO
The performance of a large-diameter chromatographic column can be drastically reduced when the solvent enters the column at a temperature different from that of the wall of the column. A radial temperature gradient inside the column will affect the physical properties of the solvent and the chromatographic behaviour of the solute resulting in a deformation of the band profile. A mathematical model is proposed to take into account the effect of a radial gradient of temperature in a large-diameter column on the chromatographic peak shape under linear conditions. The model is then compared with experimental results in preparative columns of different sizes. A good agreement between experiment and theory has been found showing a serious effect of thermal conditions on separation quality, depending on the column size. It is also demonstrated that a small difference of temperature can be helpful to compensate practical effect of frits and distribution of the sample at the extremities of the packed bed. Finally, it demonstrates the necessity to perform efficiency measurement under different thermal conditions to have a good comparison between columns.
