High-Pressure Liquid Chromatography (HPLC)

HPLC is a technique, where compounds in a mixed liquid sample are separated, identified and quantified. Usually the solid phase consists of non-polar adsorbent material, which retains compounds until they are eluted with a more polar mobile phase, the duration of retention depending on their molecular properties (mostly polarity). An online detector measures variations in an optical signal, which is correlated to the quantity of the compound. A diode-array detector (DAD) is one of the possible types of detectors, where absorption at multiple wavelengths can be followed at the same time, the range usually encompassing both UV and visible light.