The phenomena created by ban broadening in space are eliminated by the use of a retention gap in the column inlet, i.e., by keeping ca. 50-80 cm of the capillary column free of stationay phase. The extraction of the stationary phase frm the retention gap zone is easy for polar coating. For non-polar silicone stationary phases, especially if immobilized, other methods have to be applied: (a) the phase may be burnt, (b) deactivated, uncoated pre-column is connected to the column inlet or (c) the column is prepared with an inlet section free of stationay phase. Several methods for the preparation of a joint between a pre-column and the separating column aer discussed. Glued joints are considered to be the most promising. It is proposed that commercial columns should be offered with an uncoated inlet section 3 m in length. © 1982.
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