Chromatography assembly for multi-dimensional chromatography, includes a first separating column (12; 112) for separating a sample into components; a second separating column (13; 114) having different separating characteristics for further separating the components separated in the first separating column (12; 112); a collecting volume (20; 120, 121) for collecting the components from the first separating column (12; 112) before entering the second separating column (14; 114); a switching assembly (22, 24; 122, 124) for switching from a first state (FIG. 1; FIG. 3), where the components leaving the first separating column (12; 112) are collected in the collecting volume (20; 120, 121) to a second state (FIG. 2; FIG. 4) where the components collected in the collecting volume (20; 120, 121) are transferred to the second separating column (14; 114); and a detector (18; 118) for detecting sample components leaving the second separating column (14; 114). The volume of the collecting volume (20; 120, 121) is variable. A further collecting volume (121) may be provided and fluid flow can be through the first collecting volume (120) in the first state and through the second collecting volume (121) in the second state.