a liquid stream and a detector and a computer which operate to observe properties in the composition of the fluid stream and compare detected data from observed samples with standards and in accordance with parameters established by calibration calculate the characteristics of the observed samples . an integral but segmented liquid stream flows through the analysis system to provide liquid segments of observed sample and reagent . a detector scans data from the samples at the interface between these segments and information relating to the composition at the interface is analyzed by a mathematical model that permits comparison of the detected data from successively observed samples with standards and thus determines the characteristics of the samples . the segmented integral liquid stream is fashioned by step pulsing of discrete segments of reagents and samples and transporting the discrete segments to a detector . the analysis system is driven by a vacuum assembly and valves to form the segments in the absence of air so that the respective sample and reagent segments interface with each other . a plurality of source tanks provide the liquid samples and reagents for the segmented , integral liquid stream and the vacuum assembly creates a force which forms and drives the samples and reagents through conduit means , , , and to the detector .