MONITORING THE MOBILE-PHASE COMPOSITION IN SUPERCRITICAL-FLUID CHROMATOGRAPHY

Adding additional components to supercritical CO2 in supercritical fluid chromatography can extend or significantly alter the fluid solvating properties. Polar samples that are difficult to analyse using pure supercritical CO2 because of their high polarity can be separated by adding polar modifiers to the supercritical CO2. A method for monitoring the mobile phase composition in modified supercritical fluid chromatography is introduced. The amount of water or methanol dissolved in supercritical CO2 was measured using an amperometric microsensor made of a thin film of perfluorosulphonate ionomer.