Centrifuge rotor, centrifuge or ultracentrifuge comprising centrifuge rotor, sample retraction needle, method for in-situ sample retraction from a centrifuge tube

Centrifuge rotor (1) comprising:

• a rotor assembly (10) adapted for centrifugal rotation around a rotation center axis (14), with a plurality of centrifuge tube beds (16), each with a longitudinal axis (160),
• wherein each centrifuge tube bed (16) comprises a tubular cavity (162) which is defined by a cavity sidewall (162a) and a cavity bottom (162b),
• wherein at least one of the plurality of cavity bottoms (162b) comprises at least one extraction aperture (18), which connects the tubular cavity (162) to the exterior of the rotor assembly (10), characterized in that the cavity sidewall (162a) and the cavity bottom (162b) together act as a bearing surface for the outer surface of a centrifuge tube (4) when received in said centrifuge tube bed (16),
• wherein at least one closure device (2) is removably fastened to the rotor assembly (10) to seal each of the at least one extraction apertures (18) in an airtight manner, wherein each of the at least one closure devices (2) comprises a shaft (22) extending along a shaft axis (22a) from a first end (221) to a second end (222), wherein the shaft (22) is adapted to the geometry of the extraction aperture (18), wherein the first end (221) forms a partial area of the cavity bottom (162b) when the closure device (2) is fastened to the rotor assembly (10) and wherein the shape of the first end (21) is adapted to the shape of the cavity bottom (162b) to form a smooth transition of the surface of the first end (221) and the surrounding surface of the cavity bottom (162b), and
• wherein the second end (222) of the shaft (22) comprises at least one interlocking element (29) which protrudes at least partially in radial direction of the shaft (22) and wherein the rotor assembly (10) comprises at least one cutout (19a) and/or at least one pocket (19b) adapted to receive said at least one interlocking element (29) to form an interlocking structure when the closure device (2) is fastened to the rotor assembly (10).