Increased speed of analysis in isothermal and temperature-programmed capillary gas chromatography by reduction of the column inner diameter

It is shown theoretically that for an isothermal analysis the relationship of the retention time to the column diameter is . The exponent z is determined by the column pressure drop and varies between z 1 for high plate number columns and z 2 for situations of low pressure drop. Equations derived for temperature-programmed conditions also lead to the same conclusion. The validity of the expressions was confirmed by experiments with columns of 30 and 50 μm internal diameter, installed in standard chromatographic equipment. With these small-diameter glass and fused-silica columns coated with non-polar stationary phases, plate numbers between 105 and 106 were obtained. A temperature-programmed run typically can be accomplished within 8 min on an 8 m x 50 μm column having over 105 plates. Several examples of high-speed, high-resolution analysis of complex samples are given