Under gradient elution the solute will firstly migrate in initial mobile phase due to dwelling time (tD) of the system. The pre-elution of solute in initial mobile phase can be accounted for by a dimensionless value of tD/(t0kφ0), where t0 and kφ0 denote dead time and retention factor in initial mobile phase, respectively. The influence of tD/(t0kφ0) on retention time (tR) and peak compression factor (G) are discussed under linear gradient elution. A general expression for G is proposed, and two analytical forms of it which are suited for linear solvent strength model (LSSM) and quadratic solvent strength model (QSSM) respectively are presented. The well-known Poppe equation for G which is derived under LSSM is extended by taking tD/(t0kφ0) into account. The expression for G under QSSM takes into account the curvature in the plot of logarithmic retention factor vs. mobile phase composition. By taking twelve compounds degraded from lignin as analytes, the experimental and predicted chromatograms are found to be well consistent. It is shown that tD/(t0kφ0) has more effects on the prediction of tR than that of G.

中文翻译：

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初始流动相中溶质的预洗脱对线性梯度洗脱下保留时间和峰压缩的影响。

在梯度洗脱下，由于系统的停留时间（tD），溶质首先会在初始流动相中迁移。初始流动相中溶质的预洗脱可通过无量纲值tD /（t0kφ0）来解释，其中t0和kφ0分别表示初始流动相中的死区时间和保留因子。在线性梯度洗脱条件下，讨论了tD /（t0kφ0）对保留时间（tR）和峰压缩因子（G）的影响。提出了G的一般表达式，并给出了G的两种解析形式，分别适用于线性溶剂强度模型（LSSM）和二次溶剂强度模型（QSSM）。通过考虑tD /（t0kφ0）扩展在LSSM下导出的著名的G Poppe方程。QSSM下的G表达式考虑了对数保留因子与流动相组成的关系曲线中的曲率。通过将十二种从木质素降解的化合物作为分析物，发现实验和预测的色谱图非常一致。结果表明，tD /（t0kφ0）对tR的预测比对G的影响更大。