Analysis of mobile phase supply from mobile phase container

A method for use with a sample separation apparatus (10, fig 1) comprises determining a weight and volume reduction behaviour 132 according to which weight and volume of mobile phase in a mobile phase container (100, fig 1) are reduced during conveying mobile phase from a mobile phase container in the sample separation apparatus. The method may comprise determining the density of the mobile phase based on the determined weight and volume reduction behaviour, and controlling the sample separation apparatus based on the result. Alternatively, the method may include determining a weight and volume characteristic of the mobile phase container and identifying a mobile phase container based on the comparison of the determined weight and volume characteristic of the mobile phase container with pre-known, reference characteristics. Alternatively, the method may involve identifying the mobile phase, or predicting a point in time at which the mobile phase will fall below a threshold, and whether the mobile phase is sufficient to carry out one or more separation runs. Preferably, the sample separation apparatus is a liquid chromatography apparatus.