Showing papers by "Tyge Greibrokk published in 1989"

Packed capillary supercritical fluid chromatography with mixed mobile phases and light‐scattering detection

Abstract: The combination of packed fused silica columns and the laser light-scattering detector has been examined. A column, 10 cm × 0.32 mm i.d., packed with a 4-μm C18 material, was mounted in a drift tube that functioned as a column oven. The restrictor was positioned in the detector cell. Standard curves and slopes were obtained for 5–60 ng of trimyristin and Irgafos-168 with 2.9 and 5.6 mol % of n-propanol in carbon dioxide. With pressure programming at a constant modifier concentration, the relative standard deviations in peak areas were determined to be less than 4%, except for the 5-ng injections. The reproducibility of retention times was better than 0.5%. Two applications are demonstrated.

The solvent venting injection technique in capillary supercritical fluid chromatography

Abstract: A solvent venting technique for injection of volumes up to 1 μl on 50 μm i.d. SFC columns has been compared to direct injection methods. The peak broadening and peak splitting observed with direct injection have been examined and found to be related to the starting pressure, the column temperature, and the sample solvent, in addition to the sample volume. The solvent venting technique removed peak splitting and improved the column efficiency. With a proper selection of experimental conditions, the sample recovery was 100%. The major part of the solvent was eluted in 15–20 s. Several applications have been demonstrated.