Abstract: A light absorption analyzer can work in either a reflection or a transmission mode, according to which probe head is fitted to it.Light is caused to be of a desired wavelength for the analysis by passing non-monochromatic light from a high-intensity flash tube source (which is not a point source) to an interference filter. Only parallel light emanating from the filter is focused by a concave parabolic mirror on a point where at least one fibre-optic collector is positioned. This light can then be passed directly to the probe for passage through the sample, since it is only light of a specified wavelength which will have travelled parallel from the filter and will therefore be focused at the point. Some of the light is taken off a reference detector to provide a reference signal for comparison with that derived from a test detetor fed by a return fibre-optic from the probe. A comparator is programmed to give a quantitiative readout of the absorption by the test sample.

Abstract: Assays, e.g. immunoassays, based on the chemiluminescent reaction between a peroxidase enzyme, e.g. horse radish peroxidase, a chemiluminescent 2,3-dihydro-1,4-phthalazinedione, e.g. luminol or isoluminol and an oxidant, e.g. hydrogen peroxide or a perborate, are improved by carrying out the reaction in the presence of a 6-hydroxybenzothiazole, especially 6-hydroxybenzothiazole itself or firefly luciferin. Light emission from the reaction is significantly enhanced by the 6-hydroxybenzothiazole.

Abstract: An analyte in solution is made to react with a spectific reactant coated on the wave-guide thus modifying the optical properties thereof. The index of refraction of the wave-guide material is higher than that of the reaction medium which ensures that a light signal injected into said guide be carried by multiple total reflection, the distance of penetration of the evanescent wave associated with the totally reflected signal being of the same order of magnitude or greater than the thickness of the analyte-reactant product layer.

Abstract: A layer of bioactive molecules is coated on a dielectric substrate and is contacted with a solution to be analyzed containing a complex conjugate of said molecule. The rate of complexion of said conjugate moiety with the layer which is a function of its concentration in the analyte is measured by optical means and correlated with corresponding rates obtained from standard reference measurements, thus providing data for determining the unknown concentration of said conjugate moiety in the solution to be analyzed.

Abstract: The apparatus comprises a movable member (10) which carries a plurality of cuvettes (11) containing material under test. Control means cause the member (10) to be moved to bring the cuvettes (11) successively into register with a photomultiplier (16), and in that position reagent is automatically added to a cuvette, giving rise to a luminescent reaction. Light from the reaction is detected by the photo-multiplier (16) and the resultant signal processed and recorded. The control means is triggered to stop the member (10), add reagent, record the signal from the luminescent reaction, and restart the member, from a photocell (28) which is illuminated through the member (10) only when a cuvette (11) is in register with the photomultiplier (16).According to the method, sample material containing the analyte for determination is mixed with a known amount or concentration of the same analyte labelled with a substance which is capable of taking part in a luminescent reaction.

Abstract: An analyte in solution is made to react with a specific reactant coated on the wave-guide thus modifying the optical properties thereof. The index of refraction of the wave-guide material is higher than that of the reaction medium which ensures that a light signal injected into said guide be carried by multiple total reflection, the distance of penetration of the evanescent wave associated with the totally reflected signal being of the same order of magnitude or greater than the thickness of the analyte-reactant product layer.