MODEL RELEASED. HPLC analysis. Researcher using a high-performance liquid chromatography (HPLC) machine in a chemistry laboratory. HPLC is used to separate components from a mixture dissolved in a liquid. Separation takes place on beads packed inside a column inside the instrument. The beads are coated with a waxy substance that exerts a varying attraction on the components of the sample as it is pumped through the column under high pressure. The varying attraction results in the components emerging at differing rates from the end of the column. The technique can be used to detect trace amounts of a chemical. Photographed in Germany.