When Single Dimension GC Separations Fail: Exploring Real World Applications for Comprehensive Two=Dimensional GC (GCxGC)

One of the benefits of GCMS as an analytical tool is its ability to provide data which can be effectively searched against established libraries. This requires resolved or well-defined analytes, or the detection, inter alia, of lower abundance analytes which elute under highly abundant analytes. The potential for long analytical runs exists as a solution but these often fail due to retention mechanisms in GC. An approach which addresses this issue is comprehensive two-dimensional gas chromatography (GC×GC) where orthogonal selectivity between two phases facilitates separation of coeluting analytes. This poster will demonstrate several applications in which single dimension gas chromatographic separations fail to provide resolution of components of complex mixtures. In many instances, time-of-flight mass spectrometry, coupled with mathematical deconvolution algorithms, has been successfully utilized to extract pure spectra for coeluting analytes in a complex chromatogram. However, there are instances when math alone cannot solve these challenging problems. One common example is a so-called perfect coelution in which the peaks of two or more analytes apex at the exact same retention time. This leads to a mass spectrum composed of more than one analyte which cannot be mathematically resolved. Instances such as these provide an opportunity for GC×GC to demonstrate the separation power needed to successfully isolate and identify components that are often missed in one-dimensional GC separations.