Injection of large volumes of aqueous solutions in capillary supercritical fluid chromatography and sample preconcentration by multiple injections

Abstract

The possibility of using water or aqueous solutions as the solvent in capillary supercritical fluid chromatography was successfully demonstrated. Large volumes (up to 1 μl) of aqueous sample solutions were injected. Sample preconcentration was performed by means of multiple injections of aqueous sample solutions. The solutes were trapped at the beginning of the column at low density (high temperature and low pressure) and eluted using a density programme. The method can be applied to trace analysis. It proved to be linear in the range examined. Flame ionization detection was used for the studies. As this technique is not sensitive to water, no solvent peak appears, which may be an advantage for certain applications. The influence of water injections on the column performance and the reproducibility of injection was investigated.