Efficiency and resolution have been studied with a CCC apparatus classified by Y. Ito 1 as a HDES type J, and known as the HSCCC or the Multi-layer Coil Separator Extractor. It has been shown that the efficiency decreases when increasing the linear velocity of the mobile phase in the column, which can be done by increasing the flow rate, or by decreasing the volume of the mobile phase in the column. The two ways of changing the linear velocity are not equivalent, since, at constant linear velocity, the efficiency increases when the volume of the mobile phase is well balanced with that of stationary phase, For each flow rate there is a minimum value for the volume of the mobile phase, and the relationship is linear. Working under these conditions, changing both the flow rate and the volume of the mobile phase leads to an efficiency which goes through a minimum at medium flow rates. The resolution does not show this minimum: it is best at low flow rates and low volumes of mobile phase, and its variations are more important ot low flow rates. This means that, if the resolution is good at moderate flow rates, it will remain good at higher flow rates. Combining three equations, it has been possible to predict the resolution when working with the minimum volume of mobile phase for a given flow rate.
