Selecting Detectors for Compounds with No Optical Absorbance

In HPLC, the detector is selected in accordance with the analyte. Many of the detectors used are based on optical absorbance, such as UV-Vis absorbance detectors and photodiode array (PDA) detectors. Absorbance detectors have the following features: The detector sensitivity and selectivity can be adjusted by setting an appropriate detector wavelength. The sensitivity is relatively high (although it depends on the molar extinction coefficient). The relationship between the elution concentration and the detection response is linear and covers a wide range (Lambert-Beer law). The gradient elution method can be used. The stability is high. The difference between instruments is small. They perform nondestructive detection and can therefore be used for fractionation. It is partly because of this large number of features and the consequent high level of versatility that absorbance detectors are used so widely.