We describe a new analytical approach--"capsule chemistry"--for high-speed, selective analysis of a wide variety of analytes. Sequential micro-aliquots of sample and reagents are encapsulated within an inert fluorocarbon liquid. The resulting "test capsule" is introduced into a single analytical flow path, composed of a solid fluorocarbon, Teflon, where the sample is incubated, mixed, reacted, and measured as a moving series of individual tests. These randomly selective assays are processed at a rate of 720 per hour. The unique physical interaction between the liquid and solid fluorocarbon carrier materials effectively prevents detectable "carryover" of aqueous constituents between the successive test capsules. Reactions are monitored through the walls of the Teflon analytical channel at nine in-line detector stations for colorimetric and nephelometric measurements.