Department of Chemistry and Biochemistry, University of Texas at Arlington , Arlington, Texas 76019-0065, United States.
Agilent Technologies, Hewlett-Packard Strasse 8, D 76337 Waldbronn, Germany.
Anal Chem. 2018 Feb 6;90(3):2063-2069. doi: 10.1021/acs.analchem.7b04248. Epub 2018 Jan 16.
Following a brief overview of the emergence of absorbance detection in liquid chromatography, we focus on the dispersion caused by the absorbance measurement cell and its inlet. A simple experiment is proposed wherein chromatographic flow and conditions are held constant but a variable portion of the column effluent is directed into the detector. The temporal peak variance (σ), which increases as the flow rate (F) through the detector decreases, is found to be well-described as a quadratic function of /. This allows the extrapolation of the results to zero residence time in the detector and thence the determination of the true variance of the peak prior to the detector (this includes contribution of all preceding components). This general approach should be equally applicable to detection systems other than absorbance. We also experiment where the inlet/outlet system remains the same but the path length is varied. This allows one to assess the individual contributions of the cell itself and the inlet/outlet system.to the total observed peak. The dispersion in the cell itself has often been modeled as a flow-independent parameter, dependent only on the cell volume. Except for very long path/large volume cells, this paradigm is simply incorrect.
本文简要概述了液相色谱中吸光度检测的发展，重点讨论了吸光度测量池及其入口引起的分散。我们提出了一个简单的实验，其中保持色谱流动相和条件不变，但将柱流出物的一部分引导至检测器。发现随着通过检测器的流速（F）降低，时间峰方差（σ）呈二次函数关系，与/成正比。这允许将结果外推至检测器中的零停留时间，然后确定在检测器之前（这包括所有先前组件的贡献）的真实峰方差。这种通用方法应该同样适用于除吸光度以外的检测系统。我们还进行了实验，其中入口/出口系统保持不变，但路径长度发生变化。这允许评估池本身和入口/出口系统对总观测峰的单独贡献。池本身的分散通常被建模为与流动无关的参数，仅取决于池体积。除了非常长的路径/大体积池外，这种范例是不正确的。
