The use of ion-pairing principles in SFC has been demonstrated to a limited degree. The influence on the selectivity of sodium heptane sulfonate and dimethyloctyl amine (DMOA) with cyano and diol bonded phase columns has been investigated. The limited solubility of ion-pairing agents in CO2-modifier mixtures was noted as being a problem in ion-pair SFC. Elution of propranolol with 25 mM sodium heptane sulfonate in CH3OH/CO2 was reported; whereas the analyte failed to elute from the cyano packed column without sodium heptane sulfonate.