Organic liquid scintillator

In both scintillator and gas detectors, the absorption of radiation causes excitation and ionization however with the scintillation process, the absorbed energy produces a flash of light, rather than a pulse of current. The principal types of scintillation detectors found in the clinical chemistry laboratory are the sodium iodide crystal scintillation detector and the organic liquid scintillation detector. Because of the crystal detector s relative ease of operation and economy of sample preparation, most clinical laboratory procedures have been developed to measure nucfides, such as which can be counted efficiently in a crystal detector. A liquid scintillation detector is used to measure pure (3-emitters, such as tritium or C. 

The organic liquid scintillators consist of a mixture of a solvent with one or more solutes. Compounds that have been used successfully as solvents include xylene, toluene, and hexamethylbenzene (see Table 6.2). Satisfactory solutes include p-terphenyl, PBD, and POPOP. 

In addition to sodium iodide crystals, a number of organic scintillators such as stilbene, anthracene, and terphenyl have been used. In crystalline form, these compounds have decay times of 0.01 and O.l ps. Organic liquid scintillators have also been developed and are used to advantage because they exhibit less selfabsorption of radiation than do solids. An example of a liquid scintillator is a solution ofp-terphcnyl in toluene. 

The measurement of the radon content of water is based on extraction processes that exploit the high partition coefficient of radon either between gas and water or between organic liquid scintillators and water. In particular, by introducing fine gas bubbles to water, it is possible to extract radon very efficiently. Radon is thus bubbled out from water and collected in a Lucas cell. The detection limit for this method is very low, 50Bqm . ... 

The scintillation process in an organic liquid scintillator (From Kessler 1989 used by permission of Perkin Elmer)... 

Where it is required to measure neutrons in the presence of a significant y-ray background, it is possible to make use of the properties of certain scintillators to distinguish the pulses produced by neutrons from those due to y rays. This is known as a pulse-shape discrimination (PSD) system. In stilbene and some organic liquid scintillators, the pulse rise time for the fluorescence caused by the secondary electrons from a y-ray interaction is considerably shorter than that due to the recoil protons produced by neutron scattering. By the use of fast timing discriminators, it is possible to separate the pulses caused by neutrons from those due to the y rays. 

Laser dye. Organic liquid scintillator. Lemon yellow plates with blue green fluorescence (cyclohexane). Mp 178°. 

The emitted P particles excite the organic molecules which, in returning to normal energy levels, emit light pulses that are detected by a photomultiplier tube, amplified, and electronically counted. Liquid scintillation counting is by far the most widely used technique in tritium tracer studies and has superseded most other analytical techniques for general use (70). 

Organic Scintillators and Liquid Scintillation Counting , Academic Press, NY (1971)... 

Ross HJE, Noakes E, Spalding JD. Liquid Scintillation Counting and Organic Scintillators, Lewis, Chelsea, MI, 1991. 

DDT Metabolism.-- The metabolism of DDT has been studied in R and S fish, following similar protocols to chlorinated cyclodiene metabolism organic extraction (acetonitrile), thin layer chromatography of organic extracts, and liquid scintillation counting of the resultant spots (4). When S and R fish were exposed to 60 yg/l of 14C-labelled , -DDT for 4 hr, radioactivity was found in the spots which co-chromatographed with... 

Both the organic and water layers from the radioactive insecticides were counted in a liquid scintillation counter (Isocap/300, Searle). The results are expressed as nanomoles or micrograms equivalent of the substrate per mg protein. 

The combination of the picosecond single electron bunch with streak cameras, independently developed in 1979 at Argonne National Laboratory [55] and at University of Tokyo by us [56], enabled the very high time resolution for emission spectroscopy. The research fields have been extended to organic materials such as liquid scintillators [55-57], polymer systems [58], and pure organic solvents [59]. The kinetics of the geminate ion recombination were studied [55,57,59]. 

Hirayama, F. Lipsky, S. Saturated Hydrocarbons as Donors in Electronic Energy Transfer Processes New York. In Organic Scintillators and Liquid Scintillation Counting Horrocks, D.L., Peng, C.-T., Eds. Academic Press, 1971 205 pp. 

To extract the liberated fatty acids, 1.5 ml of 0.1 mM carbonate-bicarbonate buffer, pH 10.5 is added and the mixture is shaken for 10 s. Centrifugation for 45 min at 1500 xgin a swing-out rotor will separate the water from the lower organic phase. In a scintillation vial, 2 ml of the upper water phase are mixed with 50 pi of glacial acetic acid containing 500 pg ferric acid before the scintillation liquid is added (16 ml of Ecoscint toluene (7 1 volume). Liquid scintillation counting is done for 5 min and the LPL activity is calculated from the difference in counts between the blank and the sample vials [40]. 

Low-Level Waste Low-level waste (LLW) consists of contaminated dry trash, paper, plastics, protective clothing, organic liquids such as liquid scintillation samples, and the like. LLW is produced by any facility that handles radioactive materials such as nuclear power plants, medical facilities, colleges, and so forth. In the United States, commercial LLW is sent to one of three disposal sites (Barnwell, South Carolina, Richland, Washington, and Clive, Utah). Due to the limited size of these sites (and similar disposal sites through the world) and steeply escalating costs for waste disposal, the primary goal of LLW treatment prior to disposal is volume reduction, either by incineration or compaction, followed... 

There are three common types of organic scintillator. The first type is a pure crystalline material, such as anthracene. The second type, the liquid scintillator, is the solution of an organic scintillator in an organic liquid, such as a solution of p-terphenyl in toluene ( 3 g solute/L solution). The third type is the solution of an organic scintillator, such as p-terphenyl, in a solid plastic, such as polystyrene. 

The extraction of two typical agricultural products from environmental matrices were chosen as examples for the operation of this system. Diuron, a phenylmethylurea, was freshly spiked onto Tama soil. This soil was characterized and shown to have 3.1% organic material and 14 % clay fraction. In addition, a phenyl metabolite of NUSTAR, a systemic fungicide, on wheat previously unextractable by SFE was extracted. The wheat sample was not classified for its chemical composition. Both samples were treated with radiolabeled compounds (E. I. du Pont de Nemours and Company, Du Pont Agricultural Products, Wilmington, DE) and extraction results are from liquid scintillation counting of the sample extract. Chromatographic evaluation of the Diuron from soil extracts has previously been published (2). 

In this experiment, tritiated water is purified by simple distillation, and the tritium beta particles in the condensate are measured with a liquid scintillation (LS) counter. Such distillation also can collect tritiated water samples from solids. Tritium in other forms must be processed before it can be counted like tritium in water for example, tritiated hydrogen gas and tritiated organic substances can be oxidized to form water. Additional separations may be needed if the liquid or solid sample contains radioactive gases or volatile substances other than tritium that may be collected with the distilled tritiated water. Such radioactive impurities can be identified in the data output from the LS counter of an energy spectrum that differs from that of pure tritium, or of counts in energy regions where tritium counts are not found. 

A1 As Be Co, Mo, V Cu, Pb cio2 Ge Pb trace metals U, Th, Po, Ra Organic compounds in water include the following (122) spectrofluorometric, neutron activation hplc coupled to icp / aes AAS icp / aes potentiometric ion chromatography preconcentration reaction followed by spectrophotometry preconcentrated as various complexes OC-spectroscopy and liquid scintillation... 

Distribution studies with radiolabeled test substances in animals are an important part of the drug development process. Routine methods used for these studies are quantitative whole-body autoradiography (QWBA) and alternatively quantitative tissue distribution studies (QTD) with dissection of the animals and measurement of radioactivity in pre-selected organs and tissues using a liquid scintillation counter. 

Horrocks, D. L., and Peng, C. (1971). Organic Scintillation and Liquid Scintillation Counting. New York Academic Press. 

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