High performance liquid chromatography (HPLC) equipment is used to separate the components of a mixture based on different types of chemical interactions between the analysed substances and the chromatographic column. The compound passes through the chromatographic column via the stationary phase (usually a cylinder with small rounded particles with certain chemical characteristics on its surface) by pumping liquid (mobile phase) at high pressure through the column. The sample to be analysed is introduced in small quantities with an autosampler and its components are differentially slowed down depending on chemical or physical interactions with the stationary phase as they advance through the column. These components are quantified by an ultraviolet detector which responds to light absorbing substances.