Abstract: An optical waveguide with one or more coatings of reactants specific to species to be analyzed in a liquid analyte immersed therein. A light signal carried by the waveguide undergoes interaction either with the bulk analyte whereby a first signal in connection with the bulk analyte is obtained and, simultaneously, with a layer of complex resulting from the reaction of one of said specific reactant with one of said species or with two or more complex layers corresponding to two or more of said species, this generating a second (or more) signal to provide the required analytical information on said species.

Abstract: The unit consists of a cuvette and light guiding means comporting more than one waveguide element in contact with the solution to be analyzed. During operation, signals issuing from said waveguide elements provide data on two or more parameters in the solution substantially simultaneously.

Abstract: Waveguide apparatus for use in substance analysis has a waveguide, with a surface area in contact with the substance, for transmitting electromagnetic radiation along the axis of the waveguide whereby propagation characteristics of the radiation are altered in accordance with properties of the substance adjacent the waveguide. A waveguide entrance prism is positioned at the radiation entrance end of the waveguide, for guiding radiation into the waveguide. The prism has a first face arranged at an angle with the waveguide axis to cause radiation entering the prism to propagate along the waveguide. In one embodiment, a longitudinal partition is arranged adjacent the waveguide substantially parallel to the waveguide axis, for partitioning the waveguide surface area into at least two parts so that multi-substance analysis can be carried out.

Abstract: An apparatus responsive to optical changes in a waveguide when the latter is contacted with an analyte capable of reacting with a specific reactant thereto attached to the surface of said guide involves, for containing the analyte, an interchangeable round bottomed cuvette temporarily held by a suitably shaped carrier in working relationship with the optical components of the apparatus, this arrangement ensuring a correct optical orientation thereof relative to said component whatever the exact positioning of the cuvette.

Abstract: An analyte sample of blood serum is reacted with a protease in excess over that quantity required to provide a 1:1 protease:inhibitor complex. The excedent protease is then back-titrated using the reaction with diphenylcarbamyl fluoride and measuring electrometrically the liberated fluoride.