AbstractAn interface for coupling supercritical fluid chromatography to a magnetic sector mass spectrometer was developed and evaluated. The interface is based on direct introduction of the mobile phase, carbon dioxide, into the ion‐source of the mass spectrometer. The SFC‐MS system was optimized with respect to the signal‐to‐noise ratio. Under optimized conditions, the estimated detection limit forn‐pentadecane is approximately 30 ppm. Spectra obtained in the electron‐impact ionization mode show a very good similarity with library spectra. The performance of the SFC‐MS system was evaluated by the analysis of a number of test mixtures. A sample containing several low molecular mass, thermally unstable compounds, which could neither be analyzed by GC‐MS nor by LC‐MS, was analyzed. Also for the analysis of high molecular mass compounds, the coupled system showed a