Abstract: A holder (2) for sample liquid containers, e.g. Eppendorf vessels (15), is horizontally displaceable between a working position above a magnetic arrangement (4) and a heating position above a hotplate (5). The latter are supported on a baseplate (3) which can be vertically displaced by means of a lifting device (9) between a lowered passive position and a raised active position in which the magnetic arrangement (4) and the hotplate (5) act on the sample liquid in the Eppendorf vessels (15) and attract ferromagnetic particles suspended there. To improve the interaction between the ferromagnetic particles and the sample liquid, the magnetic arrangement (4) can be transversely moved by a stepping motor (6) between a first position, in which, for example, a magnetic plate (14) acts on a row of Eppendorf vessels (15) from the right side, and a second position, in which said magnetic plate (14) acts on the same row of Eppendorf vessels (15) from the left side.