Reducing working fluid dilution in liquid systems

A method of transporting a desired fluid in a channel includes: providing a working fluid to transport the desired fluid, such as a sample; providing a first segment of a first buffer fluid which is immiscible with the working fluid and the desired fluid; providing a first segment of the desired fluid; providing a second segment of a second buffer fluid which is immiscible with the working fluid and the desired fluid; providing the desired fluid to be transported and further manipulated; and transporting the desired fluid in the channel by applying a motive force to the working fluid which in turn exerts force against the desired fluid through the first and second buffer fluid. The method prevents dilution of a sample in an apparatus such as a diagnostic analyzer or an apparatus for immunohematological testing of blood. A microfluidics handling system includes a microsystem platform that has: a substrate having: a first flat, planar surface; and a second flat planar surface opposite to the first surface. The first surface includes: at least one microchannel; an optional reagent source; an optional reaction chamber; a source of motive force to transport the fluid; a working fluid in the microchannels; a first segment of a first buffer fluid which is immiscible with the working fluid and the desired fluid; a first segment of the desired fluid; a second segment of a second buffer fluid which is immiscible with the working fluid and the desired fluid; and the desired fluid to be transported and further manipulated, wherein the fluid is present in the microchannels in the order of working fluid; first buffer fluid; first segment of the desired fluid, second buffer fluid; and the desired fluid.