AbstractA simple interface between a capillary supercritical fluid chromatograph and an Extranuclear Simulscan mass spectrometer is described. The SFC column is directly inserted into the ion source through the existing GC‐interface. The system is equipped with a splitting device which allows simultaneous EI/MS and flame ionization detection when CO2 is used as the supercritical phase. The effect of source temperature and pressure on CO2 clustering was studied for optimization of source conditions. The performance of the system was evaluated with a series of model compounds and standard mixtures.