  We consider the variation of the strange quark-chemical potential in the
phase diagramme of nuclear matter, employing the order parameters and
mass-scaled partition functions in each domain and enforcing flavour
conservation. Assuming the region beyond the hadronic phase to be described by
massive, correlated and interacting quarks, in the spirit of NJL and lattice
calculations, we find the strange quark-chemical potential to attain large
negative values in this domain. We propose that this change in the sign of the
strange quark-chemical potential from positive in the hadronic phase to
negative in the partonic, to be a unique, concise and well-defined indication
of the quark deconfinement phase transition in nuclear matter. We propose also
that, for a chemically equilibrated state in the deconfined region, which
follows an isentropic expansion to hadronization via a second order phase
transition, the fugacities of the equilibrated quark flavours, once fixed in
the primordial state, remain constant throughout the hadronization process.
