Use of the isopycnic plots in designing operations of supercritical fluid chromatography. V. Pressure and density drops using mixtures of carbon dioxide and methanol as the mobile phase

The drops of pressure and density along chromatographic columns of different characteristics, eluted with different mixtures of carbon dioxide and methanol was mapped as functions of the column outlet pressure and the operating temperature. This paper extends an earlier report reporting the extent of the pressure and density drops along chromatographic columns eluted with neat CO2[1]. It illustrates the similarities and differences in the pressure and density profiles along columns operated with mixed mobile phases and with neat CO2. Numerical calculations of the pressure and density drops along columns packed with particles of different sizes, under different operating conditions (temperature, outlet pressure, and flow rate), provide important insights regarding the extent of the pressure and density drops under these operating conditions.

► We calculated the pressure and density drops along columns eluted with supercritical fluids.
► Constant mass flow rates of mixtures of carbon dioxide and methanol were considered.
► The pressure and density drops are functions of the temperature and the back pressure.
► Except near the critical point, pressure and density profiles along columns are nearly linear.