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Scintillation solutions containing surface active substances, soluble in Toluene, could be used for efficient counting of 125I. The use of Triton X-114 in the proportion 30% v/v with a Toluene-2,5-Diphenyloxazole basic scintillation solution, provides a method for the measurement of liquid and solid samples with 50% efficiency and aqueous sample capacity up to 25%.
Liquid scintillation counting of 3H-labeled whole-blood samples is severely impaired owing to quenching by blood pigments. In this study, dry oxidation and chemical solubilization followed by decolorization were the two general methods used to eliminate color quenching. Three blood volumes were examined: 0.25, 0.50, and 1.0 mL. Dry oxidation yielded complete recoveries of 3H label with counting efficiencies greater than 30% for up to 1.0 mL of blood. Although blood volumes larger than 0.25 mL can be used with chemical solubilization and decolorization, treatment of 0.25 mL of blood gave the highest counting efficiencies, with count rates comparable to those for 1.0-mL samples.
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Liquid scintillation counting has proven to be an excellent technique to standardize beta-ray emitters with good accuracy. However, the success achieved in beta-ray nuclide standardization is not extensible for radionuclides decaying by electron-capture. Last comparison of 55Fe revealed discrepancies of 5% among laboratories. This paper presents two new versions of the computer program EMI. First we consider a better simulation of the photoelectric interaction of X-rays with the scintillator cocktail (EMI 1.2); and second, a more sophisticated KL1L2L3M atomic rearrangement model (EMI 2.0). We emphasize the importance of improving the simulation of the electron capture process to achieve better standardization of electron-capture nuclides by the CIEMAT/NIST method.
The flatbed scintillation counting system (Betaplate) was used for quantitative measurement of the radioactive hybridization signal in detection of adenovirus and papillomavirus DNA in clinical specimens. In this method, 96 samples on a nylon membrane can be handled as a single entity throughout the hybridization and counting procedure. The technique is sensitive, rapid, and convenient in routine use when compared with conventionally applied methods for the numerical analysis of hybridization results. The assay principle allows simultaneous testing of large numbers of specimens.
The liquid scintillation counting standardization of pure-beta solutions containing pure-beta emitter impurities is a difficult task because, unlike that which can be achieved by using gamma-ray spectrometry, the continuous characteristics of beta spectra and the poor intrinsic resolution of LSC spectrometers do not allow an easy identification and precise determination of the activity concentration of these impurities. This problem was recently encountered in the standardization of a 32P solution in the framework of an international comparison, where the activity contribution of the impurities was over 10% of the main nuclide activity at the reference date. This paper describes the method used to identify the impurities in this 32P solution and the calculation of the detection efficiencies using the triple to double coincidence ratio model. Details on the calculation of the uncertainties of each activity and the covariances between these activities are given.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Liquid scintillation counting solutions for radioimmunoassay of hepatitis associated antigen (HBsAg) are evaluated and discussed. Data is also presented which indicates that liquid scintillation counting could be carried out by placing cut-off Ausria-125 test tubes in counting vials containing 10 ml of either Brays, Unogel, or Instagel solutions. The data suggest that Brays was the least effective and Unogel and Instagel were the most effective liquid scintillation counting solutions. This is a fundamental consideration if a laboratory is contemplating an initial investiment in counting equipment. The acquisition of a liquid scintillation counter provides additional capabilities for the clinical laboratory interested in radioisotope measurements. In addition, if a laboratory already has a liquid scintillation counter (Beta counter), the director of the clinical laboratory may elect not to purchase additional counting equipment (gamma counter) since he already has the added advantage of measuring iodine-125 with the Beta counter. The authors propose liquid scintillation (RIA) as an alternative counting system for HBsAg detection in hospital patients and donors.
Following a 10 min pulse labeling with 3H-TdR, flasks of asynchronous monolayer cultures of Chinese hamster ovary cells were subjected to mitotic selection at 2 hr intervals. The mitotic index of the selected populations was always greater than 90%. Counts per min per cell obtained by liquid scintillation counting were plotted versus time after the pulse label. Comparisons were made between cycle times obtained by the mitotic-scintillation counting method and by the standard per cent labeled mitosis technique. The resulting curves were used for calculations of the cell cycle times and the lengths of G1, S, G2 and M phases of the cell cycle. There was less than 2% difference in the cell cycle times obtained using the scintillation method as compared to times calculated from autoradiographic data obtained from individual petri dishes. The mitotic-scintillation counting technique is simple, accurate and rapid and allows the calculation of the cell kinetics parameters within 1 hr of the end of the experiment.
The reliability of the channels ratio method for determining counting efficiency in liquid scintillation counting was investigated. It was found that the efficiency of counting gels, cloudy samples, two-phase samples, samples in which the radioactive material was precipitating, and samples on solid supports could not be reliably determined from a normal quench correction curve. A curve constructed from external standard channels ratios was unreliable when mixing different vial sizes and sample volumes, but one constructed from sample channels ratios was not. It was also found that variation in instrument performance can result in large errors unless samples and standards are counted together. Statistical error changed relatively little within the range of ratios 0.3 to 0.8.
A new "foggy scintillator" was developed for the measurement of low-energy beta-emitters in air. By the use of an ultrasonic wave generator, a liquid scintillator can be converted into the "foggy scintillator". In order to obtain reasonable detection efficiency, it is necessary to prepare a liquid scintillator with a very high concentration of the first solute (PPO). The foggy scintillation counting technique avoids the trouble of the sample preparation usually necessary for the measurement of radionuclides in air, since the radionuclide in the air can be measured directly.
A major expense of radioimmunoassay involving tritiated tracers is that of liquid scintillation counting. We present a micro-scale method that markedly reduces the cost of liquid scintillation counting. The radioimmunoassay is done in 10 X 50 mm tubes. The antibody-bound tracer is precipitated with a second antibody, the precipitate is resuspended in 0.1 ml of water, and 0.3 ml of dioxane is added. One milliliter of a toluene-based scintillation cocktail is added, and the tube is capped and placed in an adapter for liquid scintilation counting. When this method was applied to a double-antibody testosterone radioimmunoassay, it performed comparably to assays counted by the usual method.
This report describes the theory and practice of anew solid scintillator technique for measurement of radiolabeled compounds useful in bioresearch. Solid scintillation counting is expected to replace liquid scintillation counting in certain applications involving non-volatile radiolabeled substrates.
Scintillation counting of beta activity on filter paper, with monoisopropylbiphenyl as a solvent of low volatility, was investigated. The method is attractive since no sample preparation is involved, and the activities are measured directly on the filter paper wetted with the scintillator solution. A linear dependence of counting rate on total activity was found for iodine-131, phosphorus-32, sodium-22, and carbon-14, and counting efficiencies were determined.
Detection of gamma emitting isotopes is achieved conventionally by using a gamma spectrometer, or in some cases by liquid scintillation counting. We applied these two methods to the detection of 51 Chromium released in a lymphocyte-mediated cytotoxic reaction. Detection in liquid scintillation appeared more efficient than conventional gamma detection: 16.74% vs 1,11%. It is therefore possible to reduce by a factor of 10 the number of target cells in the cytotoxic assay if liquid scintillation counting is used. Either method gave the same results when applied on the same samples. Liquid scintillation counting is to be preferred when high sensitivity is needed. In addition it offers the advantage of using the same apparatus for detection of gamma or beta emitting isotopes.