Fast temperature programming in gas chromatography using resistive heating

The features of a resistive-heated capillary column for fast temperature-pr ogrammed gas chromatography (GC) have been evaluated, Experiments were carr ied out using a commercial available EZ Flash GC, an assembly which can be used to upgrade existing gas chromatographs, The capillary column is placed inside a metal tube which can be heated, and cooled, much more rapidly tha n any conventional GC oven. The EZ Flash assembly can generate temperature ramps up to 1200 degrees/min and can be cooled down from 300 to 50 degrees C in 30 s. Samples were injected via a conventional split/splitless injecto r and transferred to the GC column, The combination of a short column (5 m x 0.25 mm i.d.), a high gas flow rate (up to 10 mL/min), and fast temperatu re programmes typically decreased analysis times from 30 min to about 2.5 m in. Both the split and splitless injection mode could be used, With n-alkanes as test analytes, the standard deviations of the retention t imes with respect to the peak width were less than 15% (n = 7), First resul ts on RSDs of peak areas of less than 3% for all but one n-alkane indicate that the technique can also be used for quantification. The combined use of a short GC column and fast temperature gradients does cause some loss of s eparation efficiency, but the approach is ideally suited for fast screening as illustrated for polycyclic aromatic hydrocarbons, organophosphorus pest icides, and triazine herbicides as test compounds, Total analysis times - w hich included injection, separation, and equilibration to initial condition s - were typically less than 3 min.