Sample SCF Separations

The output results of an SCF chromatogram are presented on a strip chart recorder showing the detector response on the vertical axis and the elution time on the horizontal axis. We show two examples as presented by Karey O Leary at Virginia Tech University in 1995 (results shown are by permission from http //www.cee.vt.edu/ewr/environmental/teach/smprimer/sfc/sfc.html). 

FIGURE 1.10 Example of supercritical fluid chromatography of pesticides. 

FIGURE 1.11 Resolution of silicone polymers using supercritical fluid chromatography. 

This chapter helps us to understand that while the ideal gas law PV = nRT) is generally useful in the range of temperatures above 0°C and pressures up to about 100 atm, extreme conditions can require corrections. Dalton s law leads us to begin to wonder about the behavior of individual gas molecules and the space between them. We also saw that the density of a gas can be related to the molecular weight of the gas. A calculation of the moles of gas based on the Avogadro hypothesis led us to a simple way to consider uncertainties in experimental methods according to a formula based on percent uncertainties in the variable measurements as 

While the PV curve for an ideal gas should be the positive branch of a hyperbola at a given temperature (isotherm), experimental data reveal the critical point phenomenon where a gas can condense into a liquid. The work by van der Waals corrects the ideal gas law with small terms and two parameters to formulate 

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