Packed-column supercritical fluid chromatography coupled with electrospray ionization mass spectrometry

Abstract

A new approach to combined supercritical fluid chromatography—mass spectrometry (SFC-MS) was explored using a two-pump supercritical fluid chromatograph, and a packed column with the outlet directly interfaced to an electrospray (ES) ion source attached to a single quadrupole mass spectrometer. The experimental set-up is described and preliminary results are reported for mobile phase flow-rates in the range 0.15–1 ml/min, using CO 2 modified by the addition of 1–30% (v/v) of a polar organic solvent. The combined system has a greater potential for the analysis of polar molecules by MS than earlier SFC-MS instruments that utilized capillary column SFC directly coupled to the ion source of a chemical ionization mass spectrometer. A liquid-phase ionization process was utilized for solute ion formation, and it could be applied to the determination of high-mass and polar molecules separated by packed column SFC; however, the MS response is dependent on the mobile phase composition and the SFC-ES-MS instrument is still limited to the determination of low-mass samples owing to cold trapping on some critical surfaces.