Scintillation counting

Scintillation counting Scintillation crystals Scintillation detector Scintillation detectors... 

Liquid scintillation counting is by far the most common method of detection and quantitation of -emission (12). This technique involves the conversion of the emitted P-radiation into light by a solution of a mixture of fluorescent materials or fluors, called the Hquid scintillation cocktail. The sensitive detection of this light is affected by a pair of matched photomultiplier tubes (see Photodetectors) in the dark chamber. This signal is amplified, measured, and recorded by the Hquid scintillation counter. Efficiencies of detection are typically 25—60% for tritium >90% for and P and... 

Y. Kobayashi and D. V. Maudsley, Biological Applications ofEiquid Scintillation Counting, Academic Press, Inc., New York, 1974. 

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 Liquid scintillation counting is by far the most widely used technique in tritium tracer studies and has superseded most other analytical techniques for general use (70). 

A widely used instmment for air monitoring is a type of ionization chamber called a Kaimn chamber. Surface contamination is normally detected by means of smears, which are simply disks of filter paper wiped over the suspected surface and counted in a windowless proportional-flow counter. Uptake of tritium by personnel is most effectively monitored by urinalyses normally made by Hquid scintillation counting on a routine or special basis. Environmental monitoring includes surveillance for tritium content of samples of air, rainwater, river water, and milk. 

Bransome, Jr, Ed, The Current Status of Liquid Scintillation Counting , Grune Stratton, NY (1970) 7) D.L. Horrocks C.T. Peng, Eds,... 

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

E. Rapkin, Guide to Preparation of Samples for Liquid Scintillation Counting , New England Nuclear Corp, Boston, Mass (1975)... 

In the carbon-14 expts, HMX/RDX product was isolated qualitatively, separated Into its components, and each component assayed for carbon-14 beta radioactivity using a liquid scintillation counting technique (Ref 11). DPT-l4C was isolated as an intermediate product from the reaction mixt and similarly radioassayed. For the nitrogen-15 tagged AN expts, HMX and RDX were assayed mass spectrometrically for i5N/i4N ratios from which atom %1SN contents were calcd. In die course of these expts, each tagged species was added initially and also at subsequent stages of the reaction process. The important observations and results are summarized as ... 

Radioactivity Analysis. Samples of urine, feces, and tissues were combusted to COo and analyzed for radioactivity (5). By using this method the recovery of radioactivity from samples spiked with C was 95 dt 5%. To determine the radioactivity expired as CO2, 5-ml aliquots of the solution used to trap the CO2 were added to 15 ml of a scintillation counting solution containing 4 grams 2,5-diphenyloxazole (PPO) and 0.1 grams l,4-bis-2(5-phenyloxazolyl)-benzene (POPOP) per liter of 1 1 toluene 2-methoxyethanol. Samples were counted for radioactivity in a Nuclear Chicago Mark II liquid scintillation counter. Counting eflSciency was corrected by the internal standard technique. 

Since cigarette tobacco already contains several micrograms of the TSNA, we determined the transfer rate of NNN into the smoke by spiking the tobacco column with NNN-2 - C. The smoke from such radiolabeled cigarettes is then analyzed by HPLC and the amount of unchanged NNN-2 - C is determined by liquid scintillation counting. Independent of the smoke pH, about 11% of the radioactive NNN is found in the mainstream smoke thus 41-46% of mainstream smoke NNN stems from the tobacco NNN and 54-59% are pyrosynthesized (11). 

Membranes (50 pi in a total assay volume of 100 pi) were incubated with UDP-Gal (0.1 mM) and MgSO (10 mM) in 25 mM Tris-HCl buffer pH 7.5, for 10 or 60 min. Reactions were stopped by heating at 100°C for 3 min. Lupin galactan (0.1 mg) was added as a 0.1% solution, methanol was added to give a final concentration of 70% by volume, and the tubes were capped, heated at 70°C for 5 min and centrifuged (13000g 5 min). Supernatants were discarded or retained for analysis. Pellets were washed twice more with 70% methanol at 70 C and the supernatants were discarded. The final pellets were either dissolved in preparation for scintillation counting, or were suspended in water and freeze dried in preparation for analysis. 

Instead of scraping and manual collection of the adsorbent, the band can be sucked off the plate with a Vacuum-cleaner -type apparatus. Dekker [50] described an apparatus for the isolation of compounds from layers by elution and direct Millipore filtration, and Platt [51] designed a zone collector that used vacuum to transfer separated zones from layers direcdy to vials for hquid scintillation counting of radioactivity. 

The metabolic and pharmacokinetic profile of sucralose (this is a novel intense sweetener with a potency about 600 times that of sucrose) in human volunteers was studied by Roberts and coworkers [82]. Part of this study was realized using PLC in the following chromatographic system in which the stationary phase was silica gel and the mobile phase was ethyl acetate-methanol-water-concentrated ammonia (60 20 10 2, v/v). Separated substances were scraped off separately, suspended in methanol, and analyzed by filtration, scintillation counting, or enzymatic assay. It was shown that the characteristics of sucralose include poor absorption, rapid elimination, limited conjugative metabolism of the fraction absorbed, and lack of bio-accumulative potential. 

Liquid chromatography/mass spectrometry Lower limit of detection Limit of detection Limit of quantitation Florseshoe crab hemocyanin Liquid scintillation counting Matrix-assisted laser desorption/ ionization mass spectrometry m -Maleimidobenzoy 1-A -Hydroxysuccinimide 1 -Cyclohexyl-3-(2-Morptiolino-ethyl)carbodiimide rnetlio-/ -Toluenesulfonate (same as CDI)... 

Using a simple solvent extraction procedure to minimize matrix effects, a diclofop-methyl immunoassay was developed for milk, a number of edible plant products, and other matrices. Gas chromatography (GC) and liquid scintillation counting (LSC) of a C-labeled analyte were used as reference methods to compare with enzyme immunoassay (EIA) results. The methods were well correlated, with comparison of EIA... 

Guilmette RA, Bay AS. 1981. Radio assays of americium or curium in biological material by isoctyl acid phosphate solvent extraction and a liquid scintillation counting. Anal Chem 53 2351-2354. 

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