Protection of the media bed in the chromatography devices has dynamic axial compression

This invention relates to chromatography device comprising: - a column (12) for receiving between its two ends (16a, 16b) a chromatographic bed (14) and a fluid to be chromatographed, a layer (48) fluid being defined between a surface of the bed (14) and one end (16a) of the column (12), - a piston (36) sliding in the column (12), the piston (36) one end (16a , 16b) of the column (12), - at least a first probe (45, 46) of the bed surface of detection (14), the probe (45, 46) being mounted on the end (16a) of the column (12) defining the layer (48), - means (52) of the piston position setting (36) depending on the detection of the surface of the bed (14) by the probe (45, 46). The invention also relates to methods for separating at least two compounds of a fluid to be chromatographed and adjustment methods of the position of the piston relative to the surface of the chromatographic bed by implementing the device has the chromatographieL'invention advantage of effectively separating compounds of the fluid to be chromatographed while ensuring the bed protection