A fluidic centripetal apparatus for testing components of a biological material in a fluid is presented. A bottom-fillable chamber is coupled to an entry channel for receiving the fluid, the chamber inlet being provided at an outer side of the bottom-fillable chamber. A container is wholly provided in a retention chamber and contains a liquid diluent, until it releases it upon application of an external force, restoring the fluidic connection between the liquid diluent and the fluid in the retention chamber. The retention chamber can have a flow decoupling receptacle for receiving the fluid, located at the outer side of the retention chamber and interrupting a fluidic connection between the entry and exit of the retention chamber. A test apparatus and a testing method using a fluidic centripetal device for testing components of a biological material in a fluid are also provided.