BAND BROADENING DURING MOBILE-PHASE CHANGE IN UNIFIED CHROMATOGRAPHY (GC-SFC)

Band broadening brought about by changing the mobile phase from the GC mode to the SFC mode in unified chromatography is discussed. Its orig in is shown to result from several factors: the replaceable volume of the tubing and valves in front of and following the column; the volume , internal diameter, and film thickness of the open tubular column; th e initial pressure of the supercritical mobile phase; and the column t emperature. Improvements to restrict band broadening were achieved by optimizing the system and its operating conditions.