Various embodiments relate to systems andor methods for sample preparation that can be used for biochemical andor molecular biology procedures involving small volumes, for example, micro volumes or smaller. If more contacting devices have been provided, they are preferably axially spaced apart and are disposed along the inner surface of the riser reactor. The receiving end sealingly engages a first valve of a pressurized container, and the dispensing end sealingly engages a second valve such as a service port of an automobile air conditioner. The evaluation unit determines time-variable changes in motion and identifies a change in motion of the object as tapping.