Abstract: The invention relates to a CO2-absorption device within an elemental analysis instrument, comprising at least one combustion reactor and one detector, connected by a pneumatic line for the gasses undergoing analysis emerging from the combustion reactor, along which said CO2-absorption device is arranged downstream of the combustion reactor and upstream of the detector. In order to accelerate the operational cycle and improve efficiency without excessive bulk, two regenerable CO2 filters, valve means for feeding the gasses undergoing analysis to one of said filters, alternating between one another for each analysis, and for supplying a regenerating flow of wash gas to the second filter, in the opposite direction with respect to the direction of flow of the gas undergoing analysis in the same filter are envisaged, as well as means for temporarily heating the filter during the regeneration stage.