Abstract: A continuous flow system is disclosed in which successive liquid segments are established containing different related components of a fluid package, such as an analysis mixture, separated by at least one immiscible segment, passed along a first section of a conduit, combined in a second section of the conduit and mixed while passing along a third section of the conduit, so as to provide a completely mixed segment. This system permits the delayed on-line mixing of different components of an analysis mixture, such as samples with reagents or diluents, as well as mixing and interaction of such components in a single conduit.