How Desirable Detector Characteristics Influence your Chromatographic separations?
探测器的作用
A detector is the final component in the chromatographic system and provides real time information on the separated components. After separation of the components by the chromatographic column they move sequentially to the detector and generate response in proportion to the concentration of solute in the mobile phase stream. Chromatographic detection is based on a set of physical properties such as light absorption, fluorescence, light scattering, refractive index changes, electrical conductivity or differences in mass of separating species. The sensitivity and selectivity of the response is dependent on detector characteristics.
Desirable Detector Features
探测器功能在结果质量中起着至关重要的作用
- 对样品和流动阶段的惰性
A detector made of material that is not inert to the mobile phase or the sample components is bound to give erroneous results due to loss of analyte or extra peaks resulting from reaction products
- High sensitivity towards solute over mobile phase
检测器不应响应流动相组成的变化，除了散装属性检测器（例如折射率探测器）。检测器应在注入样品之前给出无噪声稳定的基线。
- Low cell volume
Cell volume should be small enough to prevent overlap of eluting peaks. Commonly available cell
volumes are in the range 2-8μl. Small cell volume mean less dispersion but on the other hand
larger cell volumes provide greater sensitivity. Optimum use of cell volume will give best results.
检测极限is the lowest concentration of the substance which can be detected using a detector. It is defined as the concentration which will produce a signal to noise ratio of 3:1. However, authentic quantitation can be obtained at signal to noise levels of at least 10:1.
- Fast Response Time
一个敏感的探测器是一个提供快速response to changes in mass of analyte reaching it. Slow response can have adverse effect on peak shape so an ideal detector should produce instantaneous response to mass changes.
- Large Linear Dynamic Range
Dynamic range and linear dynamic range are often synonymously used but are different features. The dynamic range is the solute concentration range over which the detector output will be dependent .The linear dynamic range on the other hand is that range of concentration over which the response is linear with respect to concentration. The choice of a detector is governed by its linear dynamic range over the desired concentration levels as well as sensitivity and selectivity.
真正的检测器很少符合所有理想的特征，但幸运的是，色谱技术根据分离和检测原理提供了广泛的选择。您必须根据优化结果和成本注意事项来决定自己的选择。
Genial!