Separation and identification of sulfanilamides by capillary supercritical fluid chromatography Fourier transform infrared spectroscopy

The separation of several sulfanilamides by capillary SFC using a capillary column coated with a biphenyldimethyl silicone column has been achieved. A very high starting pressure (similar to 200 atm) and final pressure (similar to 500 atm) was used to elute these very polar solutes. A universal SFC-FT-IR interface has been made by modification of a commercially available direct deposition GC-FT-IR interface. A new heating device allowed a partial solution to the problem of restrictor plugging by very polar compounds eluting from capillary columns. The low detection limit (about 1 ng for sulfamethazine) allows trace amounts of compounds in complex mixtures to be detected and identified provided that they are chromatographically separable. When methanol-modified CO2 was used as the mobile phase to increase the separation efficiency of capillary SFC for polar analytes, results were not encouraging because of the poor stability of the stationary phase in the presence of methanol. (C) 1997 Elsevier Science B.V.