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

초록

A simple method for the addition of methanol to supercritical CO<inf>2</inf> is described. Carbon dioxide, the most widely used mobile phase in supercritical fluid chromatography, is a relatively non-polar fluid, and hence addition of small amounts of polar modifiers could be necessary to migrate polar solutes. In this paper, a new mixing device was developed, in which high porous stainless steel filters were used to generate methanol-modified carbon dioxide mobile phase. When supercritical CO<inf>2</inf> goes through the mixing device, the modifiers held within the small pores of filters can be dissolved in the pressurized supercritical fluids. High porous stainless steel filter with 2μm porosity was used in our mixing device. To measure the amount of methanol dissolved in supercritical CO<inf>2</inf> after the mixing device, a fuel cell type modifier sensor, which was made by depositing gold and platinum on a porous plastic disc was used.