Abstract: In a method for reducing the latent low-level phosphorescence of laboratory glassware, the glassware is illuminated by infrared light with a wavelength of about 780 nanometers. A suitable infrared light source can be a xenon flash apparatus fitted with an infrared light filter. A single flash from the xenon apparatus can substantially reduce the latent low-level phosphorescence of laboratory glassware to a baseline phosphorescence level.

Abstract: A spectrophotometer incorporating a pulsed light emitting diode as a source of radiation. The light emitting diode emits substantially monochromatic light thus negating the need for a separate wavelength control. The spectrophotometer may incorporate a pair of light emitting diodes for performing bichromatic spectrophotometric determinations. The light emitting diodes are pulsed with a duty cycle and pulse amplitude such that it is possible to obtain a higher amplitude pulse than the light emitting diode could sustain at a continuous voltage input level. Continuous voltages at this level would damage the light emitting diode.

Abstract: The changes in the redox potentials of cultures of a microorganism with and without a tested growth inhibiting agent are monitored during the phase of growth in which the redox potential is normally positive and the rate of potential change is approximately linear. Effective growth inhibiting agents produce a measurable decrease in the change of the redox potential to a more negative value within less than one hour. A sensible signal indicative of the growth inhibiting action of the tested agent may be obtained from a comparator by storing an amplified signal indicative of the redox potential at a first time and feeding the stored signal together with another amplified signal obtained less than one hour thereafter to the comparator.

Abstract: A human body fluid is analyzed for the presence of one member of the group consisting of an antigen and an antibody capable of specifically combining with the antigen by depositing a specimen of the fluid to be analyzed on an inert solid substrate and by volatilizing the water in the specimen under mild conditions which leave the one member as a deposit on the surface of the substrate. The surface then is contacted with the other member, which carries a labeling agent, for a period sufficient for combining the members if the one member is present. Any amount of the labeled member not combined with the one member thereafter is removed, and a sensible signal indicative of the presence of labeing agent on the substrate is generated.

Abstract: The present invention encompasses an internal reflectance spectrometer comprising:(a) a prism adaptable for optically coupling test sample to one surface thereof;(b) a means for irradiating the test sample with light of wave length absorbed by the test sample, said means directing light to enter the test sample from the prism surface having test sample thereon at an angle between the critical angle and about 35.degree. less than the critical angle, said light refracted in the test samples so that said light is internally reflected from the test sample remote from the prism surface; and(c) a means for detecting the internally reflected light.The instrument of the present invention is a full range absorbtion spectrometer.

Abstract: Hepatitis associated antigen (HAA) in human blood serum is precipitated on HAA-specific antibodies immobilized on the inner wall of a plastic tube. A solution of HAA-specific antibodies tagged with fluorescein is held in contact with the deposited antigens until a portion of the antibodies from the solution is affixed to the antigens. The residual, tagged antibodies in the solution are exposed to a light pulse, and the resulting fluorescence is measured as an inverse indication of HAA in the blood serum.