We investigate the effects on column efficiency of methanol, acetonitrile,
ethanol, and 1-propanol used as modifiers in packed-column SFC. C-18, pheny
l, and cyano columns were used with both nonpolar and polar solutes. For hi
ghly retained nonpolar solutes, addition of modifier significantly increase
d apparent column efficiency, especially for the C-18 column. For polar sol
utes, the presence of modifier dramatically improved retention and efficien
cy with an apparent efficiency dependence on modifier type and amount. Temp
erature and pressure effects on efficiency were also studied.