Multidimensional packed capillary column supercritical-fluid chromatography using a flow-switching interface

Abstract

A two-dimensional supercritical-fluid chromatographic (SFC—SFC) system with a flow-switching interface was used with 250 μm I.D. packed capillary columns to separate polycyclic aromatic hydrocarbons (PAHs) in a standard coal tar extract. A solvent-venting injection technique was also used which allowed the injection of several microliters of sample. Compared to open-tubular columns, packed capillary columns provided shorter analysis times and higher sample capacities; compared to conventional size packed columns, they provided higher efficiencies and lower volumetric flow-rates, allowing the total effluent to be introduced into a flame-based detector without the need for splitting.The performance of packed capillary SFC—SFC was compared to that of open-tubular capillary SFC—SFC. In the first dimension, separation according to the number of aromatic rings was achieved as desired within 30 min, two times faster than previously reported for an open tubular column using the same sample. However, the selectivity and efficiency obtained in the second dimension, using a packed capillary, was not sufficient to fully separate all of the PAH isomers.