Addition and measurement of water in carbon dioxide mobile phase for supercritical fluid chromatography

Abstract

A method for the addition of water to supercritical CO₂ is described. Carbon dioxide, the most widely used mobile phase in supercritical fluid chromatography, is a relatively non-polar fluid, and hence the addition of small amounts of polar modifiers could be necessary to migrate polar solutes. In this work, supercritical CO₂ is delivered from the pump to a µ-Porasil column that is saturated with water. After passing through the µ-Porasil column, supercritical CO₂ is changed to a new mobile phase with different polarity, and it is possible to separate polar samples by using this new mobile phase. The amount of water dissolved in supercritical CO₂ is measured by an amperometric microsensor, which is prepared from a thin film of perfluorosulfonate ionomer.