INSTRUMENTATION FOR COMPREHENSIVE 2-DIMENSIONAL CAPILLARY SUPERCRITICAL FLUID-GAS CHROMATOGRAPHY

A two-dimensional supercritical fluid-gas chromatography system was constructed and evaluated. A 50-mum i.d. capillary column coated with a 50 % cyanopropyl polysilixane stationary phase was used as the first-dimensional column. Group-type separations of polycyclic aromatic hydrocarbons, based on the number of aromatic rings, were achieved using this column under SFC conditions. A 25-mum i.d. liquid crystal column was used as the second-dimensional column under GC conditions. The effluent from the first column (SFC) was received continuously by the second column (GC) through a thermal desorption modulator. The thermal desorption modulator (prepared at the head of the second column) generated a series of concentration pulses from the first column effluent. These concentration pulses served as injections to the second column, and were developed into a corresponding series of high-speed chromatograms. Group-type sample bands from the first column were separated into individual components on the second column. All sample substances passed through both columns to generate two sets of retention data, which could be used for more accurate compound identification,