Effects of Perchloric Acid on High Temperature Liquid Chromatography

Abstract

The effects of the chaotropic agent perchloric acid on high temperature liquid chromatography (HTLC) with water as mobile phase have been investigated over a temperature range from 130°C to 200°C. Aniline, N-methylaniline, 3-ethylaniline and N,N-dimethylaniline were used as analytes. Similar to the effects of increasing the organic content of the mobile phase in regular reverse phase HPLC, the increase of column temperature in HTLC results in the decrease of capacity factors for all the aniline test compounds. By adding low concentrations of perchloric acid in the mobile phase, the capacity factors of the anilines also decrease which is equivalent to the increase of column temperature. Comparisons of HClO₄ gradient and temperature program for the separation of the four anilines in HTLC are presented.

Keywords:

• Anilines
• Chaotropic additive
• High temperature LC
• Perchloric acid

Notes

∗R = Resolution.