Department of Chemistry, University of Louisville, Louisville, KY 40292, USA.
J Chromatogr A. 2012 Oct 19;1260:193-9. doi: 10.1016/j.chroma.2012.08.068. Epub 2012 Aug 28.
A method of calculating the second dimension hold-up time for comprehensive two-dimensional gas chromatographic (GC×GC) data was developed by incorporating the temperature information of the second dimension column into the calculation model. The model was developed by investigating the relationship between the coefficients in each of six literature reported nonlinear models and the relationship between each coefficient and the second dimension column temperature. The most robust nonlinear function was selected and further used to construct the new model for calculation of the second dimension retention time, in which the coefficients that have significant correlation with the column temperature are replaced with expressions of column temperature. An advantage of the proposed equation is that eight parameters could explain the second dimension hold-up time as well as retention time corresponding to n-alkanes and column temperature in the entire chromatographic region, including the chromatographic region not bounded by the retention times of n-alkanes. To optimize the experimental design for collecting the isothermal data of n-alkanes to create the second dimension hold-up time model, the column temperature difference and the number of isothermal experiments should be considered simultaneously. It was concluded that a total of 5 or 6 isothermal experiments with temperature difference of 40 or 50 °C are enough to generate an accurate model. The test mean squared error (MSE) of those conditions ranges from 0.0428 to 0.0532 for calculation of the second dimension hold-up time for GC×GC data.
开发了一种计算全二维气相色谱（GC×GC）数据二维保留时间的方法，该方法将二维柱温信息纳入计算模型。通过研究文献中报道的六个非线性模型中每个系数与各系数和二维柱温之间的关系，建立了该模型。选择了最稳健的非线性函数，并进一步用于构建新的模型，以计算二维保留时间，其中与柱温具有显著相关性的系数用柱温的表达式代替。该方程的优点是，八个参数可以解释整个色谱区域的第二维保留时间、正构烷烃对应的保留时间和柱温，包括正构烷烃保留时间未限定的色谱区域。为了优化收集正构烷烃等温数据以创建第二维保留时间模型的实验设计，应同时考虑柱温差和等温实验的数量。结论是，总共进行 5 或 6 次温差为 40 或 50°C 的等温实验，足以生成准确的模型。在这些条件下，测试的均方误差（MSE）范围为 0.0428 至 0.0532，用于计算 GC×GC 数据的第二维保留时间。
