Comparison of packed column and capillary column supercritical fluid chromatography and high-performance liquid...

The role of supercritical fluid chromatography (SFC) as a viable technique for analyzing agricultural products has been investigated using packed and capillary column methodology. The goal was to question the strengths and weaknesses of each of the techniques as possible approaches to separation strategies for thermally labile compounds as compared to the currently used high-performance liquid chromatography methodology. Representative herbicides have been examined with the techniques to compare such factors as linearity of response, limit of detection and reproducibility. In the literature so far, a direct numerical comparison of these three techniques for the analysis of real samples has not been presented. Results indicate that faster analyses, lower detection limits and greater injection to injection reproducibility are obtainable with packed column SFC. No appreciable difference in the linearity of response between the three techniques was noted. It has been well documented that the capillary SFC affords greater efficiencies and higher resolution [H. E. Schwartz, LC.GC, Mag. Liq. Gas Chromatogr., 5 (1987) 14]. Capillary SFC can also be interfaced to a variety of detectors not as easily accomplished with packed column SFC. Capillary SFC therefore still has a viable position in the analysis of low and moderate molecular weight and polarity molecules.