Overview of HPLC Detectors
- HPLC analysis requires a detector to monitor the compounds themselves in order to quantify and identify the compounds separated in the column. In other words, detector plays a role of “eyes” for HPLC analysis.
Appropriate detectors are selected based on the properties of the target compound and the affinity of the analytical conditions. Table 1 lists the HPLC detectors and their characteristics. - Table 1 HPLC detectors
Detector Target Compounds Absorbance UV-absorbing compounds Fluorescence Fluorescent compounds Refractive Index All Evaporative Light Scattering All（Exclude non-volatile compounds） Conductivity Cation, Anion Mass Spectrometry Ionic compounds
In general, compounds with characteristic structures tend to be highly selective and sensitive for detection. Absorbance detectors such as ultraviolet absorption detectors and photodiode array detectors are commonly used for HPLC analysis because many target compounds have chromophores due to double bonds in their molecular structures.
For non-UV absorbing compounds, they can be detected with other characteristics such as ionicity. Compounds that fluoresce upon irradiation with a specific wavelength can be detected with a fluorescence detector. Detectors that can detect all compounds, such as a refractive index detector and an evaporative light scattering detector, are described as “universal detectors”.