DSM Resolve, P.O. Box 18, 6160 MD Geleen, The Netherlands.
J Chromatogr A. 2013 Jul 5;1297:179-85. doi: 10.1016/j.chroma.2013.04.021. Epub 2013 Apr 13.
In this paper two tunable two-dimensional gas chromatography setups are compared and described in which the secondary dimension consists of two different capillary columns coupled in series. In the first setup the selectivity of the second dimension can be tuned by adjusting the effective column length of the first secondary dimension column, simply by sliding it stepwise back or forward through the GC×GC modulator. In the second setup, in which the first secondary dimension column is installed in a separate GC-oven (oven-2), the overall selectivity of the second dimension can be tuned by adjusting the oven-2 temperature offset with respect to the main oven. The contribution of the first secondary dimension column to the overall secondary dimension separation can be decreased by applying a higher temperature offset. A real-life sample, the headspace of a coffee powder, was used to demonstrate the added value of tunable GC×GC by solving coelutions of some specific aroma compounds. Besides optimizing the overall GC×GC separation, by altering the second dimension column selectivity, these set-ups also offer enhanced possibilities for qualitative analysis. By stepwise altering the selectivity of the second dimension, classes of compounds showing similar retention behavior could be discriminated.
本文比较并描述了两种可调二维气相色谱系统，其中二级维度由两个串联的不同毛细管柱组成。在第一种设置中，可以通过滑动第一根二级柱在 GC×GC 调制器中前后移动来调整第二维度的有效柱长，从而调整第二维度的选择性。在第二种设置中，第一根二级柱安装在单独的 GC 烘箱（烘箱 2）中，通过调整烘箱 2 相对于主烘箱的温度偏移，可以调整第二维度的整体选择性。通过施加更高的温度偏移，可以降低第一根二级柱对整体二级分离的贡献。使用实际样品——咖啡粉的顶空，通过解决一些特定香气化合物的共洗脱问题，展示了可调 GC×GC 的附加价值。除了通过改变第二维度柱选择性来优化整体 GC×GC 分离之外，这些设置还为定性分析提供了增强的可能性。通过逐步改变第二维度的选择性，可以区分具有相似保留行为的化合物类别。
