梯度液相色谱中梯度曲线变形对色谱峰宽的影响

在梯度液相色谱中,溶剂混合以及轴向扩散等因素会使梯度曲线发生变形,而这在阶梯梯度以及高斜率的线性梯度中表现得尤为明显。本文探讨了这种梯度曲线变形对色谱峰宽的影响。首先以C18色谱柱为固定相,甲醇-水为流动相,联苯和苯乙酮为样品,测得不同线性梯度和阶梯梯度条件下的色谱峰。然后以205 nm为检测波长,记录相应条件下未接色谱柱时甲醇的响应值,得到柱入口处的梯度曲线。接着根据所设定的梯度条件以及柱入口处测得的梯度曲线,分别计算相应情形中色谱峰宽的理论值,将其与实验值进行了比较。研究结果表明,梯度曲线的变形会对色谱峰宽产生影响。当将这种影响考虑在内后,理论值与实验值更为吻合。

Influence of the distortion of gradient profile on peak width in gradient liquid chromatography

In gradient liquid chromatography, the gradient profile may be distorted because of the effects of solvent mixing and axial dispersion. Such effects will be significant especially when stepwise gradient and linear gradient with high slope are applied. In this work, we discussed the influence of the distortion of gradient profile on the peak width. Firstly, the chromatographic peaks were measured under linear and stepwise gradient conditions where a C18 column was used as the stationary phase, a mixture of methanol and water as the mobile phase, and biphenyl and acetophenone as the samples. Then, the response of methanol under corresponding conditions was recorded by disconnecting the column and the detection wavelength was set at 205 nm. The gradient profile at the column inlet was calculated from the methanol response profile. The theoretical values of the peak width were calculated from the set gradient profile and the gradient profile obtained at the column inlet respectively. The theoretical values were compared with the experimental ones. It is shown that the distortion of gradient profile does affect the peak width. When such influence is taken into account, the theoretical and experimental values of the peak width are well consistent.