Automated Sample Fractionation and Analysis Using a Modular LC-GC System


App Note 2/1992

Multidimensional capillary gas chromatography, and, in its ultimate form, comprehensive GC, result in the highest obtainable peak capacity and overall resolution. The combination of GC techniques is however restricted to the analysis of volatile (GC amenable) compounds and the separation mechanism is mostly based on volatility (boiling point separation). High molecular weight compounds or very polar compounds cannot be analyzed or will contaminate the analytical system. The potentials of multidimensional HPLC, in this respect, are much larger and very specific separations based on hydrophobicity, polarity, ion strength, molecular size or affinity can be obtained. HPLC, on the other hand, cannot offer the same peak capacity and overall resolution as GC. HPLC and GC are thus quite complementary to each other and therefore the on-line combination of the two techniques is very interesting. Recently on-line HPLC-GC equipment became commercially available. In this paper, a new automated and modular system based on a flow cell and large volume PTV injection is presented.