Abstract: The invention relates to a device for concentrating solutions by partly freezing-out solvent, consisting of a vessel surrounded laterally by an insulated cooling jacket, the vessel comprising a stirring means and a draining aperture at the bottom. The cooling jacket does not extend down to the lowermost portion of the vessel. The lowermost portion of the vessel in which the stirring means and the draining aperture are accommodated, externally comprises, preferably is surrounded by, a heating medium.

Abstract: The invention relates to a pre-column of pressure-resistant material for preconcentrating at elevated pressure substances to be chromatographed, which column consists of a vessel-shaped body which narrows internally towards the two ends and has means for sealing connections, upstream to an inlet tube for the liquid to be preconcentrated and downstream to a separating column.The invention also relates to a device for a liquid chromatography system, comprising one or more pre-columns, optionally one or more separating columns, and a coupling member, and to a coupling member for said device.