The chosen composition of the mobile phase depends on the intensity of interactions between various sample components ("analytes") and stationary phase ("e.g.", hydrophobic interactions in reversed-phase HPLC). Depending on their affinity for the stationary and mobile phases, analytes partition between the two during the separation process taking place in the column. This partitioning process is similar to that which occurs during a liquid–liquid extraction but is continuous, not step-wise. In this example, using a water/acetonitrile gradient, more hydrophobic components will elute (come off the column) late, once the mobile phase gets more concentrated in acetonitrile ("i.e.", in a mobile phase of higher eluting strength).