  Bounds analogous to entropic uncertainty relations allow one to design
practical tests to detect quantum entanglement by a collective measurement
performed on several copies of the state analyzed. This approach, initially
worked out for pure states only [Phys. Rev. Lett. 107, 150502 (2011)], is
extended here for mixed quantum states. We define collectibility for any mixed
states of a multipartite system. Deriving bounds for collectibility for
positive partially transposed states of given purity provides a new insight
into the structure of entangled quantum states. In case of two qubits the
application of complementary measurements and coincidence based detections
leads to a new test of entanglement of pseudopure states.
