Use of SFC/MS for the confirmation of peak identities in the SFC/FID chromatogram of olestra

Abstract

Abstract. Open tubular supercritical fluid chromatography (SFC) with flame ionization detection (FID) has been used for characterizing olestra, a mixture of fatty acid sucrose esters. In this publication, we describe SFC/mass spectrometry (SFC/MS) of olestra using the direct fluid introduction interface. Chemical ionization spectra were used in confirming SFC/FID peak identities. Electron ionization SFC/MS of olestra was also investigated. Both major and minor component peaks in the SFC chromatogram of olestra were characterized. A slight modification of the interface-probe tip was necessary for operation at higher temperature. A procedure was developed for tuning and calibrating the instrument in the 10-4O00-u mass range, chemical ionization mode using Ultramark 3200, a perfluorinated polyether. The use of additional pumping in the form of liquid nitrogen cooled cryopumps was key in providing good signal-to-noise ratios for the latereluting (i. e., eluting at higher mobile phase pressures and flow rates) olestra components.

Supercritical Fluid Chromatography and Extraction

“…Cryopumping was shown to enhance signal by a factor of 5 in some cases. Cryopumping was later used to assist in the identification of high molecular weight components of olestra, a mixture of fatty acid sucrose esters (123). Buecherl et al built and tested an interface, incorporating a second restriction and a stage of pumping between the SFC restrictor and the ion source, for coupling open-tubular SFC to highresolution MS (124).…”

“…Combining two 50-µm-i.d., 10-m-long columns enhanced the separation of one critical pair by 23%. The SFC/MS characterization of olestra, a noncaloric fat replacement, was described by Pinkston and Bowling (123). Both CI and EI spectra of major and minor components were obtained using a modified direct fluid introduction interface.…”