Agilent Technologies, Hewlett-Packard Str. 8, D 76337 Waldbronn, Germany; IMTEK - Department of Microsystems Engineering, University of Freiburg, D-79110 Freiburg, Germany.
ROZING.COM Consulting, D 76228 Karlsruhe, Germany; Emeritus Agilent Technologies Research Fellow, 2012, D 76228 Karlsruhe, Germany.
Talanta. 2018 Sep 1;187:200-206. doi: 10.1016/j.talanta.2018.04.101. Epub 2018 May 3.
High performance liquid chromatography (HPLC) with a solvent gradient and absorbance detection is one of the most widely used methods in analytical chemistry. The observed absorbance baseline is affected by the changes in the refractive index (RI) of the mobile phase. Near the limited of detection, this complicates peak quantitation. The general aspects of these RI-induced apparent absorbance effects are discussed. Two different detectors with fundamentally different optics and flow cell concepts, a variable-wavelength detector equipped with a conventional flow cell and a diode-array detector equipped with a liquid core waveguide flow cell, are compared with respect to their RI behavior. A simple method to separate static - partly unavoidable - RI effects from dynamic RI effects is presented. It is shown that the dynamic RI behavior of an absorbance detector can be well described using a single, relatively easy-to-determine metric called the G-index. The G-index is typically in the order of a few seconds and its sign depends on the optical flow cell concept.
高效液相色谱（HPLC）采用溶剂梯度和吸光度检测，是分析化学中最广泛使用的方法之一。观察到的吸光度基线受到流动相折射率（RI）变化的影响。在检测限附近，这会使峰定量复杂化。本文讨论了这些由 RI 引起的表观吸光度效应的一般方面。两种具有根本不同光学和流动池概念的不同检测器，即配备常规流动池的可变波长检测器和配备液体芯波导流动池的二极管阵列检测器，就其 RI 行为进行了比较。提出了一种简单的方法，可将静态（部分不可避免）RI 效应与动态 RI 效应分离。结果表明，吸光度检测器的动态 RI 行为可以使用一个简单的、相对容易确定的度量标准（称为 G 指数）来很好地描述。G 指数通常为数秒，其符号取决于光学流动池的概念。
