Reproducibility in capillary supercritical fluid chromatography: Comparison of injection techniques

An analysis of the precision obtained using commercially available microvalve injectors is reported for three modes of injection: conventional split; timed‐split; and direct. Results from this study show that good precision (< 3% RSD for external standard and < 1% RSD for internal standard methods) can be obtained with capillary supercritical fluid chromatography (SFC). However, particular attention must be paid to the type of valve used, the orientation of the column relative to the valve, the mode of interfacing or connecting the column to the valve, and the type of pressure or density programming used for the analysis as all of these factors will affect the reproducibility.