Gas chromatographic method

A gas chromatographic method, comprising:

• loading a mixture onto a first column packed with a stationary phase wherein mixture components of interest have different affinities for the stationary phase, the column is maintained at an elution temperature profile wherein the temperature increases along the column length from the inlet to the outlet;
• flowing the mixture through the first column to effect at least a partial separation of the mixture components;
• flowing the effluent from the first column through a second column packed with a stationary phase wherein mixture components of interest have different affinities for the stationary phase, the column is maintained at a temperature profile wherein the temperature decreases along the column length from the inlet to the outlet;
• and
• recovering the separated components of the mixture from the outlet of the second column.

A gas chromatographic method, comprising:

• loading a mixture onto a column packed with a stationary phase wherein mixture components of interest have different affinities for the stationary phase, the column is then provided with a variable elution temperature profile decreasing along the column length from the inlet to the outlet of the column;
• flowing the mixture through the column to effect at least a partial separation of the mixture components;
• and
• recovering the separated or partially separated components from the outlet of the column.