Two-dimensional fluid separation with push-pull modulation

A sample separation apparatus for separating a fluidic sample, the sample separation apparatus comprising:

• a first-dimension separation unit for separating the fluidic sample, wherein the first-dimension separation unit comprises a first-dimension outlet for outputting the fluidic sample or fractions thereof after treatment by the first-dimension separation unit;
• a second-dimension separation unit for further separating the fluidic sample or fractions thereof after treatment by the first-dimension separation unit, wherein the second-dimension separation unit comprises a second-dimension inlet fluidically coupled to the first-dimension outlet;
• a modulation unit fluidically coupled between the first-dimension outlet and the second-dimension inlet at a first coupling point, wherein the modulation unit is configured to withdraw fluid from the first coupling point and to eject fluid into the first coupling point;
• and
• a second-dimension fluid drive fluidically coupled to a second coupling point between the first-dimension outlet and the second-dimension inlet, wherein the second coupling point is located downstream from the first coupling point, and the second-dimension fluid drive is configured to generate a fluid flow for driving at least part of the fluidic sample after treatment by the first-dimension separation unit through the second-dimension separation unit,
• wherein the first-dimension separation unit is fluidically coupled to the second-dimension separation unit via the first coupling point and the second coupling point, with the first coupling point and the second coupling point each comprising three fluid terminals and providing a permanent fluid communication between the three fluid terminals.