HPLC is a technique whereby all relevant components are separated before being measured. At the beginning of the analysis, a small sample (10-100 µL) is delivered  into an HPLC column via the mobile or eluent phase. The sampled solution’s components interact with the stationary phase, passing through the column at different speeds depending on their level of interaction. The least interacting components move faster through the column (elute), while the stronger interacting components move slowly. A detector at the end of the column identifies the separated components. The detector’s signal is recorded and used to calculate the concentration of the analyzed components.