A two-dimensional liquid chromatography (2D-LC) apparatus and method of its use, the apparatus constructed with (1) a first dimension (first-D) having at least one first chromatography column, (2) at least one multi-port stream selector in fluid communication with the at least one first chromatography column for receiving an effluent therefrom, and (3) a second dimension (second-D) having a plurality of second chromatography columns, each second chromatography column in fluid communication with a corresponding port of the at least one multi-port stream selector for receiving an effluent fraction of the effluent from the at least one first chromatography column, thereby enabling simultaneous chromatographic separation by the plurality of second chromatography columns of a set of multiple effluent fractions outputted from the at least one first chromatography column.