SUPERCRITICAL FLUID CHROMATOGRAPHY MASS-SPECTROMETRY USING A QUADRUPOLE MASS FILTER QUADRUPOLE ION TRAP HYBRID MASS-SPECTROMETER WITH EXTERNAL ION-SOURCE

The combination of capillary supercritical fluid chromatography (SFC) and ion trap mass spectrometry using an external, differentially-pumped ion source is described. This was accomplished using a capillary SFC instrument with direct, on-column injection, and a custom-built, direct-introduction interface to a quadrupole mass filter/ion trap (Q/trap). The hybrid mass spectrometer was equipped with a standard EI/CI ion source and operated with conventional ion trap detector (IM) electrodes and electronics. The hybrid mass analyzer system allows the ion trap to tolerate the high mobile-phase flow rates introduced to the ionization region of the mass spectrometer. The instrument was characterized and optimal operating conditions were determined with perfluorotributylamine, anthracene, and methyl docosanate. A sample of 80 fmol of anthracene provided a molecular ion peak with a S/N ratio of 20. Once the operating parameters were optimized, two less volatile mixtures were characterized. The first was a poly(dimethyisiloxane) with an average molecular weight of 770. The second was a derivatized surfactant for which the full structure was not known in advance but which was elucidated from the SFC/MS data.