A capping and de-capping apparatus for capping and de-capping capable tubes disposed in a rack with a two dimensional array of apertures for holding said tubes, said apparatus comprising: - a rack support for supporting said rack, - a head unit supporting a two-dimensional array of capping and de-capping grippers, each capping and de-capping gripper including a capping and de-capping socket unit configured for engaging and retaining a cap, said capping and de-capping grippers being aligned with tube apertures defined by the array in said rack, - a drive mechanism for moving the rack support and head unit relatively towards and away from one another, to cause engagement or disengagement of at least one capping and de-capping socket unit with or from a cap of at least one tube; and - a drive system for rotating at least one capping and de-capping gripper and the capping and de-capping socket unit attached thereto, wherein rotation of the capping and de-capping socket unit, after engagement of the at least one capping and de-capping socket unit with at least one cap, causes attachment of the at least one cap to the at least one tube within the rack when the at least one capping and de-capping gripper rotates in one direction and causes detachment of the at least one cap from the at least one tube when the at least one capping and de-capping gripper rotates in the opposite direction, characterized in that - the at least one capping and de-capping gripper has a throughgoing passage extending through the at least one capping and de-capping gripper and the capping and de-capping socket unit attached thereto, - an ejector pin moveably arranged within said throughgoing passage; - and wherein said ejector pin is configured to perform a translational movement relative to the at least one capping and de-capping gripper and capping and de-capping socket unit attached to said gripper thereby effecting a release of a cap retained within the capping and de-capping socket unit. - a rack support for supporting said rack, - a head unit supporting a two-dimensional array of capping and de-capping grippers, each capping and de-capping gripper including a capping and de-capping socket unit configured for engaging and retaining a cap, said capping and de-capping grippers being aligned with tube apertures defined by the array in said rack, - a drive mechanism for moving the rack support and head unit relatively towards and away from one another, to cause engagement or disengagement of at least one capping and de-capping socket unit with or from a cap of at least one tube; and - a drive system for rotating at least one capping and de-capping gripper and the capping and de-capping socket unit attached thereto, wherein rotation of the capping and de-capping socket unit, after engagement of the at least one capping and de-capping socket unit with at least one cap, causes attachment of the at least one cap to the at least one tube within the rack when the at least one capping and de-capping gripper rotates in one direction and causes detachment of the at least one cap from the at least one tube when the at least one capping and de-capping gripper rotates in the opposite direction, - the at least one capping and de-capping gripper has a throughgoing passage extending through the at least one capping and de-capping gripper and the capping and de-capping socket unit attached thereto, - an ejector pin moveably arranged within said throughgoing passage; - and wherein said ejector pin is configured to perform a translational movement relative to the at least one capping and de-capping gripper and capping and de-capping socket unit attached to said gripper thereby effecting a release of a cap retained within the capping and de-capping socket unit.