Abstract: The invention relates to a changer mechanism for individual measurement of radioactive samples in a gamma counter. The changer mechanism comprises an identifying element for identifying sample containers of different sizes and a transferring device for transferring the sample containers to the measuring unit for measuring, and back therefrom after measuring. According to the invention, the changer mechanism comprises a lifting device having a grip unit for lifting and transferring the sample from the transfer unit to the measuring unit. The grip unit is provided with grip elements for transferring samples of different sizes based on the information obtained from the identifying unit.

Abstract: The present invention provides a scintillation counter that includes a measuring chamber accommodated to take the sample and viewed by two photodetectors, preferably photomultipliers, that can be operated in coincidence. Associated with the chamber is an additional scintillator, preferably an inorganic crystal scintillator, optically isolated from the chamber by a light-permeable wall and mounted so that the scintillation light generated in the additional scintillator is guided predominantly only to one of the two photodetectors. A comparator is used for registering pulse amplitude disparity between the photodetectors to distinguish low-disparity, sample generated pulses and high-disparity, additional scintillator generated pulses.

Abstract: A method for correction of the counting error in liquid scintillation counting in the attenuation of light passing through a sample solution is measured before or after the actual liquid scintillation counting takes place. By means of the attenuation measurement the error in the liquid scintillation counting result, caused by the colorness of the sample solution, and/or by the counting apparatus, is corrected. The apparatus has a liquid scintillation counter provided with cylinder shaped optics. A photometer is incorporated in the liquid scintillation counter. By means of the photometer, the attenuation of light passing through the sample solution is measured before or after the actual liquid scintillation counting measurement, where said attenuation is caused by the colorness of the sample solution and/or due to features of the apparatus.

Abstract: The counting error due to variations in the counting efficiency as a function of the volume of the sample is corrected. The sample is placed into a sample container which is placed into a vertically positioned cylinder shaped counting chamber. Photomultiplier tubes are disposed on the opposite ends of the counting chamber. At least two of the following spectra are measured in the coincidence counting: the sum spectrum q observed by both of the photomultiplier tubes, the spectrum q(y) observed by the upper photomultiplier tube and the spectrum q(a) observed by the lower photomultiplier tube. The counting error is corrected by the correction coefficient obtained from these spectra.

Abstract: A gain stabilization system for photomultiplier tubes using a pulsed light source, preferably a light emitting diode (LED), the signal of which is detected at the first dynode and at the anode. The gain of the photomultiplier tube is stabilized by keeping the ratio between the two signals constant.

Abstract: Liquid scintillation counter includes a memory having stored spectra of known counting efficiencies and known levels of quench, for the isotopes to be meansured. A device extracts from the spectra, using the determined quench level value for each of the N isotopes, a reference spectrum representing a pure isotope spectrum at the determined quench level. A device determines for each extracted reference spectrum a factor by which the extracted reference spectrum is to be multiplied in order to fit the sum of the multiplied reference spectra to the sample spectrum. Each factor is directly related to the amount of each isotope in the sample.

Abstract: Liquid scintillation counter includes a memory having stored spectra of known counting efficiencies and known levels of quench, for isotopes to be measured. A device extracts from the spectra, by using the determined quench level value for each of the N isotopes, a reference spectrum representing a pure isotope spectrum at the predicted quench level. A device determines for each extracted reference spectrum a factor by which the extracted reference spectrum is to be multiplied in order to fit the sum of the multiplied reference spectra to the sample spectrum. Each factor is directly related to the amount of each isotope in the sample. A device computes a goodness-of-fit value and predicts a new value for the quench level based on this goodness-of-fit value. A method in liquid scintillation counter includes predicting a first value of the quench level of the scintillation sample.

Abstract: To produce a quench calibration function for a liquid scintillation counter having stored a basic correlation between a quantity to be quench calibrated and a quench index, the value of the quantity to be quench calibrated and the value of the quench index for at least one reference sample is measured by measuring means from said basic correlation, the value of the quantity to be quench calibrated for the measured value of the quench index for each reference sample is evaluated by evaluating means. Then the difference or ratio between the measured and the calculated values of the quantity to be quench calibrated for each reference sample is calculated by calculating means, whereupon said calculated difference or ratio as a function of quench index is approximated by approximating means, and said basic correlation and said function of quench of quench index are combined into the quench calibration function by combining means.

Abstract: An arrangement for improving the counting of liquid scintillation samples including a plurality of separate sample wells, a plate holder surrounding the sides of each sample well so that each plate holder forms an optically separate compartment for each sample well, at least one photomultiplier tube adjacent each sample well, and a coating of light reflective or light scattering material on the inner surfaces of said plate holders.

Abstract: An apparatus for counting liquid scintillation samples which includes a sample plate containing a plurality of cup-shaped sample wells, a photomultiplier assembly over the tops of said cup-shaped sample wells, a photomultiplier assembly beneath the bottoms of said cup-shaped sample wells and light reflective tubes extending upwardly from said lower photomultiplier assembly and surrounding each cup-shaped sample well.

Abstract: In a biospecific multianalyte assay the use of microspheres and fluorescent labels with substantially different fluorescence decay times, is combined. The assay is performed in a suspension of microspheres in the form of a pool of different microsphere categories, where the categories represent different analytes. The microspheres belonging to the respective categories are first coated with a specific reactant, i.e. the microspheres function as a solid support for the reactant and for a biospecific reaction. Fluorescent labels having a short decay time are used to identify the category of each individual microsphere, while fluorescent labels having a long decay time are used to determine the concentration of a particular analyte on the microsphere by means of the biospecific reaction.

Abstract: In a method of producing a carrier for a plurality of radioactive samples to be monitored in a liquid scintillation counter,wells are provided in a rigid plate (1) of a photon attenuating material in that holes disposed in a matrix configuration are covered from one side of the plate (1) by a first photon permeable foil (2),sample carrying cut-outs (3) from a sorption sheet on which samples have been deposited are placed in said wallsa scintillation fluid is added to the wells, andthe wells are sealed by a second permeable foil (4) to keep the cut-outs (3) and the scintillation fluid within the respective wells.

Abstract: In a liquid scintillation counter the light output from a liquid scintillation sample containing radioactive isotopes of unknown activity is measured by means of a detector. A pulse height analyzer having discriminators that are combined to define pulse height windows, is connected to the detector for measuring and temporarily storing count rates for each of the windows. Moreover, there are means for determining a value for the quench level of the sample. According to the invention the number of pulse height windows is at least N+1, when the number of isotopes is N,N being .gtoreq.2. There are memory means for storing for each of said windows representations of counting intensities determined by measuring calibration samples of each isotope at different levels of quench.

Abstract: Compound having the following structure: ##STR1## R is a direct chain or branched alkylene group comprising 2-8 carbon atoms,n and m are 0 or 1,Y is a carboxylic or phosphonic acid, andX is an active functional group which permits covalent coupling to a bio-organic molecule.

Abstract: Method to determine the degree of chemical quench and the degree of color quench in liquid scintillation samples in order to find the correct counting efficiency for the samples. Scintillation pulses produced by the liquid scintillation solution as a result of an isotopic decay or in response to radiation from an external .gamma.-radiating source, are counted in a counter comprising two photodetectors working in coincidence, means for determining the value of one quench parameter dependent on the overall level of quench in the solution, and means for determining the value of another quench parameter predominantly dependent on the level of color quench in the solution. The counting efficiency for the sample can be determined on the basis of these two quench parameters.

Abstract: The invention relates to a liquid scintillation counter comprising at least two photodetectors (2,3) for viewing a scintillation solution (1) in which both real multiphoton events and single photon events take place, and producing logic pulses and amplitude pulses in correspondence to these events, the amplitude of these amplitude pulses being a function of the number of photons that reach the photodetectors (2,3) for each of said events.

Abstract: A photomultiplier used in liquid scintillation counting has an envelope, a base, an anode, a curved dynode structure and a photocathode. A specimen is inserted in a measuring area of the envelope for liquid scintillation counting. The photocathode has a concave surface, so that the specimen is encircled by the photocathode as completely as possible. The photocathode is positioned at a concave window of the envelope, so that a maximum number of photons directly impinge on the photocathode.

Abstract: Method for calibrating a liquid scintillation counter comprising, for a number of reference solutions containing isotopes of known decay rates, the counting of a number of coincident pulses caused in at least two photodetectors by photons produced by the decay of the isotopes within a first known time interval, for obtaining the scintillation pulse frequency of each reference solution and the calculating of the counting efficiency for each reference solution by dividing said scintillation pulse frequency by the known decay rate.

Abstract: Method for quantitative determination of a biospecific affinity reaction in which an immunochemical compound labelled with a lanthanide chelate is used which can be detected by means of time-resolved fluorescence in which the amount of labelled compound present in the biospecific affinity reaction can be measured without the separation of free and biospecifically bound labelled compound having to be carried out.

Abstract: Method for fluorescence spectroscopic determination of a biological substance provided with a marker consisting of a lanthanide chelate complex formed by a lanthanide coupled to the substance via a chelate forming compound, such as an EDTA-analogue, the lanthanide ion before the detection is dissociated from the active substance for instance by adding a buffer with a pH value below 3.5 and a splitting detergent, whereafter the excitation in the determination takes place in the solution in the presence of a .beta.-diketone by using a short radiation pulse and the fluorescence from the marker is detected when the fluorescence from the noise sources has substantially ceased.