Henry T. Kalinoski

Capillary supercritical fluid chromatography-mass spectrometry

Abstract The physical and chemical characteristics of supercritical fluids have prompted the development of supercritical fluid chromatography (SFC) for the analysis of labile and less volatile compounds. High-resolution chromatographic separations with efficiencies approaching those of gas chromatography and high speed analyses are possible in capillary SFC using pressure programming methods and narrow bore columns. Further refinement of the SFC—mass spectrometry (SFC—MS) interface provides the basis for extension to more polar fluid systems with greater solvating power and the selectivity and sensitivity of mass spectrometric detection. The use of polar modified fluids has been facilitated by advances in understanding of supercritical fluid phase behavior. Fluid mixtures have been prepared for analysis of more polar, higher molecular weight analytes, that allow mild chromatographic temperatures and full exploitation of selectivity offered through control of fluid pressure ( i.e. , density). Continuing development of the SFC—MS interface has led to designs which can be near routinely applied with fluids such as carbon dioxide, and providing enhanced transport of truly nonvolatile compounds to the mass spectrometer ionization region. These advances also include an SFC interface to a high resolution, dual electric magnetic sector instrument, allowing supercritical fluid solvents to be exploited for on-line extraction—mass spectrometry for characterization of complex, often otherwise intractable, materials.

Analytical applications of capillary supercritical fluid chromatography-mass spectrometry

Abstract Capillary chromatographic analyses of thermally labile, less volatile and higher molecular weight compounds can be accomplished using supercritical mobile phases due to the combination of solvating powers and attractive mass transport properties. Recent advances in the use of small bore (25–50μm) capillary columns, rapid pressure programming methods, and polar mobile phases have yielded high-sensitivity and high-speed analyses with chromatographic resolution approaching that of conventional capillary gas chromatography. Mass spectrometry (MS) provides a nearly universal detector for supercritical fluid chromatography (SFC), and the ease with which capillary SFC can be directly coupled with the mass spectrometer avoids the complications inherent in liquid chromatography (LC)—MS interfaces. Capillary SFC can be interfaced with both electron impact and chemical ionization (CI) modes of operation, and high selectivity and sensitivity as well as structural data can be obtained through appropriate choice of CI reagents. Recent developments in capillary SFC—MS and applications to several compound classes are described.