Abstract: The present invention provides a method for determining a background count rate in liquid scintillation counting. The method comprises measuring an external standard spectrum (201, 202) of a sample, determining, from the external standard spectrum, an external standard count rate within an energy window (203), determining, based on the external standard count rate within the energy window, a background reference parameter, and determining, based on the background reference parameter, the background count rate from a background reference curve (301).

Abstract: The present invention provides a method for determining a background count rate in liquid scintillation counting. The method comprises measuring external standard spectra of a sample, determining, from the external standard spectra, a triple to double coincidence ratio and a quench parameter, determining, based on the triple to double coincidence ratio and the quench parameter, a background reference parameter, and determining, based on the background reference parameter, the background count rate from a background reference curve.

Abstract: The present invention provides a method for determining a background count rate in liquid scintillation counting. The method comprises measuring an external standard spectrum (201, 202) of a sample, determining, from the external standard spectrum, an external standard count rate within an energy window (203), determining, based on the external standard count rate within the energy window, a background reference parameter, and determining, based on the background reference parameter, the background count rate from a background reference curve (301).

Abstract: A method to correct measurement error in a resonance energy-transfer assay, including exciting anti-Stokes photoluminescent donors with at least one wavelength of light which is greater than an emission wavelength of acceptor molecules; measuring emission at the acceptor's emission wavelength and which differs from the donor's emission wavelength in at least two different time windows; a first time window within the time window defined by the excitation light pulse and a second non-overlapping time window which follows the first time window; and correcting the emission signal, which includes signals originating from non-radiative and radiative energy transfer, within the first time window by estimating the ratio of the signals from non-radiative and radiative energy transfer or the signal originating from radiative energy transfer using at least one emission signal measured in the second time window.

Abstract: A homogenous bioassay including a first group including an acceptor which is a short lifetime fluorescent compound capable of energy transfer, and a second group including a quencher which is capable of energy transfer from an acceptor. The increase or decrease of the acceptor's fluorescence resulting from lengthening or shortening of the distance between the acceptor and quencher is measured. The bioassay also includes a third group including a donor for energy transfer to the acceptor, which donor is an up-conversion fluorescent compound, a long-lifetime fluorescent compound or an electrogenerated luminescent compound. The first group includes a tag, the third group includes a binder having a high affinity for binding to the tag. Fluorescence of the acceptor is brought about by exciting the donor resulting in energy being transferred from the donor to the acceptor.

Abstract: This invention relates to a homogenous bioassay for use in measurement of biological activity, its modulation or analyte concentration of a sample, said bioassay comprising a first group comprising an acceptor, which acceptor is a short lifetime fluorescent compound capable of energy transfer, and a second group comprising a quencher, which quencher is capable of energy transfer from an acceptor. The increase or decrease, respectively, of fluorescence of said acceptor due to the decrease or increase, respectively, of energy transfer from said acceptor to said quencher resulting from lengthening or shortening, respectively, of the distance between said acceptor and quencher is measured.

Abstract: This invention relates to a method to correct for error in an anti-Stokes photoluminescence measurement in a Foerster-type resonance energy-transfer assay. The method comprises the steps of exciting anti-Stokes photoluminescent molecules, ions, phosphors, chelates, or particles, i.e. donors of the assay, with one wavelength or multiple wavelengths of light wherein the wavelength or wavelengths are greater than that of an emission wavelength of acceptor molecules in the assay; measuring emission light signal at a wavelength, which is the emission wavelength of the acceptor molecules in the Foerster-type resonance energy-transfer assay, and which differs from the emission wavelength of the anti-Stokes photoluminescent donor in at least two different time windows; a first time window within the time window defined by the excitation light pulse, i.e.

Abstract: A photodetector comprising a photoemissive surface capable of liberating photoelectrons. Photoelectrons are detected by a MOSFET having a floating gate, which is suitably charged before measurement in such a way that photoelectrons can cause a change in charge of the floating gate. The detected change indicates the amount of light received by the detector.

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 cathode and at the anode. The gain of photomultiplier tube is stabilized by keeping the ratio between the two signals constant.

Abstract: A method and a liquid scintillation counter for measuring a sample, a mixture of the specimen to be analysed and a scintillator, in a liquid scintillation counter where the sample (14) is measured with two photo multiplier tubes (23, 24) situated on different sides of the sample. The photo multiplier tubes situated on different sides of the sample operate in coincidence. Asymmetric samples are measured in such a way that the counting efficiency is measured with the photo multiplier tubes (23, 24) operating in coincidence ad calculated using the amount of coincidence pulses, whereas the amplitude and the pulse height distribution are measured only with one photo multiplier tube (23 or 24).

Abstract: An invention for preventing optical crosstalk in a process of counting liquid scintillation samples deposited in a sample plate, the sample plate composed of a plurality of sample wells, the optical crosstalk being caused by mutual optical affection between samples deposited in the sample wells. Sample wells are provided with tubes made of material impermeable but reflective or scattering for scintillation light generated by the samples.

Abstract: A method for scintillation counting and a scintillation counter exploiting a coincidence technique, in which the coincidence resolving time is flexible and can be automatically adjusted to fit the scintillation characteristics of each sample separately. This is accomplished by measuring during a short initial period the pulse length of the scintillation pulses, and adjusting the coincidence resolving time of the coincidence analyzer before the actual counting of the sample.

Abstract: A method for correcting measuring values when measuring liquid scintillation samples deposited on sample plates by a photodetector which will be affected by scintillation photons from other samples in the plate in addition to the sample being measured. Said correction is done by pre-determining affection of the other samples of the plate as a function of quench level and correcting observed measuring values using this information.

Abstract: An arrangement for counting liquid scintillation samples on a sample plate in a liquid scintillation counter having at least one photomultiplier tube. The sample plate contains a plurality of open-bottomed wells sealed with at least one filtration membrane impregnated with a solid meltable scintillator. The arrangement includes a sample plate holder for holding and transporting the sample plate in the liquid scintillation counter. The holder includes a device to hold sample plates of different sizes and a device to enable transportation of the sample plate in the liquid scintillation counter.

Abstract: The objective of the present invention is a method for determining two or more radioactively labeled ligands simultaneously in the same sample. According to the invention the ligands are determined with proximity assay so that for determining said ligands support materials with different scintillation characteristics are employed, each said support material having attached onto it molecules specifically binding one of said ligands. The support material consists totally or partially of scintillator.

Abstract: A detection material for ionizing radiation. The material is solid at room temperature but meltable to a fluid at a temperature of about 100.degree. C. One essential component in said detection material is a low molecular weight aromatic polymer, preferably a thermoplastic resin that contains low molecular weight polymer molecules of styrene and/or styrene derivatives. The detection material optionally contains a hot melt polymer and a wax-like substance, such as paraffin.

Abstract: A method for correcting measuring values when measuring liquid scintillation samples deposited on sample plates by a photodetector which will be affected by scintillation photons from other samples in the plate in addition to the sample being measured. Said correction is done by pre-determining affection of the other samples of the plate as a function of quench level and correcting observed measuring values using this function.

Abstract: A method for performing liquid scintillation counting by the liquid scintillation counter that measures radioactive samples on a measurement support, such as a filter plate or alike, which has the sample associated therein. According to the method, the detection material, such as scintillator, is added to the measurement support before the measurement. The method according to the invention is characterized by adding detection material, such as scintillator, in melted form into the measurement support and performing the measurement after the detection material has solidified. On the filter plate is added for instance a mixture of paraffin and scintillator. One component in the detection material can be plastic scintillator.

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 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.