Feasability of neat carbon dioxide packed column comprehensive two dimensional supercritical fluid chromatography

The design and implementation of comprehensive two dimensional supercritical fluid chromatography (SFC) using neat carbon dioxide as the mobile phase is described. Two conventional supercritical fluid chromatographs were hyphenated via an on line comprehensive 2D liquid chromatography like interface; it consisted of a two loop switching valve allowing the collection of the first dimension column effluent, the second dimension separation of a fraction being performed during the time allowed for the collection of the subsequent fraction of the first dimension eluent. Both dimension separations were monitored via UV detection; for the second dimension, the main flow was diverted to implement flame ionisation detection for the detection of hydrocarbons and the construction of the corresponding colour plots. Some key parameters related to the interfacing of the two dimensions and the chromatographic conditions used in both dimensions are discussed. In this preliminary report, the feasibility of comprehensive 2D SFC is demonstrated on synthetic mixtures of hydrocarbons and its potential on real sample analysis is illustrated by the separation of coal derived vacuum distillate.

► This study is the first report on true on-line SFC × SFC using neat carbon dioxide as the mobile phase.
► The modification of an LC × LC like interface is described.
► The feasibility of the technique is shown using test mixtures.
► The potential of the technique is demonstrated on a vacuum distillate from coal tar liquefaction.