Abstract: A microplate assembly for use in analyzing samples captured on a filter medium comprises a carrier plate, a holding tray, a collimator, and a cover film. These elements are generally rectangular in shape and are sized to stack on top of one another. The holding tray is positioned within the carrier plate, the collimator and filter medium are positioned within the holding tray with the filter medium positioned beneath the collimator, and the cover film is sealed over the collimator. To prepare samples in the microplate assembly for analysis, the samples are captured on the filter medium and the filter medium is placed in the holding tray. After adding scintillation cocktail or luminescent substrate to the filter medium, the collimator is placed over the holding tray with the filter medium positioned between the collimator and the holding tray and the samples disposed in the sample wells.

Abstract: The present invention provides a method of increasing the duration of detectable photon emission of a luciferase-luciferin reaction. The method provides a luciferase-luciferin reaction in which photon emission can be detected for up to and including eight hours. A method of the present invention can also be used to detect the presence of luciferase in biological samples. The present invention also provides a composition used in detecting the presence of luciferase in biological samples.

Abstract: The present invention provides a process of quantifying the number of viable cells in an aqueous suspension of cells using an energy-emitting non-hazardous probe and a probe-trigger. The process provides quantification data in short periods of time without the use of hazardous materials. A process of the present invention can also be used to quantify negatively charged particle number, assay for cytotoxicity, assay for cell proliferation and assay for cell differentiation. Still further, the present invention provides an assay kit for quantification of cells or negatively charged particles.

Abstract: Apparatus and a method for determining a quench-indicating parameter of a test sample utilizing a liquid scintillation counter are disclosed. The number of counts in a spectrum resulting from subtraction of a spectrum generated without an external source of radiation from a spectrum generated with an external source of radiation is utilized. The total number of counts is cumulatively summed from a higher energy level to a lower energy level and a curve representing this sum is generated. A portion of this curve is fitted with a function such as a straight line and the intersection of that function with the zero count axis is the intersection energy level which is an indication of the measure of quench of the test sample.