In gas chromatography (GC) large volume injection of samples containing very high molecular weight analytes presents unique problems. Standard programmed-temperature vaporizing or on-column large volume injection systems cannot be used, mainly due to instrumental difficulties. A new, simple solution to this problem is presented. If short, wide-bore columns are used at carrier gas velocities above optimum, the cloud of vapor formed upon evaporation of the solvent can be rapidly discharged from the system by the column flow alone. Hence, in medium-resolution GC, large sample volumes (e.g., 50 L) can be injected using a standard on-column injector. Neither a retention gap nor a solvent vapor exit is needed. The absence of column connectors makes this setup extremely rugged. The optimization of the direct on-column large volume injection is described. The applicability of the new technique for the injection of large volumes of triacylglycerides and heavy mineral oil fractions is shown. It is demonstrated that the new technique is relatively insensitive toward solvent composition. This makes the new method eminently suited for combination with gradient liquid chromatography preseparations.
|Number of pages||7|
|Journal||Journal of Microcolumn Separations|
|Publication status||Published - 2000|