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PubMed2004

A simple method for 210Pb determination in geological samples by liquid scintillation counting.

A simple procedure for the determination of 210Pb in geological samples using liquid scintillation counting is presented. Following the acid digestion of the sample, the method uses sulphate precipitation for the radiochemical separation. Finally, lead oxalate is precipitated, and once re-dissolved, it is mixed with ULTIMA GOLD AB scintillator cocktail. The measurement is performed using a low-level LKB Quantulus 1220 spectrometer and the two-window technique. Calibration studies were performed to evaluate the interference of 210Bi in the 210Pb measurement. The method was tested on a geological reference sample, and gave satisfactory results and high reproducibility.

Bismuth↗
PubMed1975

Use of internal vial for determining quench correction in scintillation counting of heterogeneous media.

An insert vial situated at the center of the counting medium and containing a standard count has been used for quench correction in the liquid scintillation counting of gels containing suspensions of silicic acid scrapings from thin layer chromatoplates. The method has provided a simple and direct means of routine count correction for a range of 14-C-labeled lipid classes following separation on thin layer chromatoplates. The use of insert vial provides several advantages over other methods for the count correction of these suspensions.

Carbon Radioisotopes↗
PubMedDate not supplied

Half-life measurements of 87Rb by liquid scintillation counting.

The specific activity of natural 87Rb was measured by means of 4pibeta liquid scintillation counting in a two-photomultiplier-tube spectrometer. 3H-efficiency tracing was used together with the CIEMAT/NIST method to obtain the detection efficiency. For this purpose a new parameterization of the shape factor for the third forbidden non-unique beta-transition was performed. The hygroscopic behaviour of the salts used for sample preparation was studied. The half-life of 87Rb was found to be T1/2 = 4.967(32) x 10(10)y.

Half-Life↗
PubMed2000

Analysis of detection-efficiency variation techniques for the implementation of the TDCR method in liquid scintillation counting

Detection efficiency variation is often used in liquid scintillation counting in order to evaluate a parameter in the detection efficiency calculation model. The aim of this paper is to compare the effects of three different detection efficiency variation methods in the activity measurement of three pure-beta radionuclides: 3H, 63Ni and 14C. Some general conclusions concerning the TDCR method are drawn.

Journal Article↗
PubMed2002

Comparison of the absorption of micronized (Daflon 500 mg) and nonmicronized 14C-diosmin tablets after oral administration to healthy volunteers by accelerator mass spectrometry and liquid scintillation counting.

Daflon 500 mg, is a micronized purified flavonoid fraction, containing 90% w/w diosmin and 10% w/w of flavonoids expressed as hesperidin, used clinically in the treatment of chronic venous insufficiency and hemorrhoidal disease. This study was designed to investigate the influence of particle size on the overall absorption of diosmin after oral administration of micronized (mean particle size = 1.79 microm, with 80% of particles having a size lower than 3.45 microm) and nonmicronized diosmin (mean particle size = 36.5 microm, with 80% of particles comprised between 19.9 and 159 microm). In a double blinded, cross-over study design, 500 mg tablets containing trace amounts (approximately 25 nCi) of (14)C-diosmin were administered to 12 healthy male volunteers as a single oral dose. Accelerator mass spectrometry and liquid scintillation counting were used for the measurement of (14)C-diosmin in urine and feces. Absorption of (14)C-diosmin from the gastrointestinal tract, measured by the urinary excretion of total radioactivity, was significantly improved with the micronized (57.9 +/- 20.2%) compared with the nonmicronized material (32.7 +/- 18.8%). Statistical comparison of the urinary excretion of the two pharmaceutical formulations showed this difference to be highly significant (p = 0.0004, analysis of variance). The overall excretion of the radiolabeled dose was 100% with mean +/- SD of 109 +/- 23% and 113 +/- 20% for the micronized and nonmicronized forms, respectively. The results of this study show: 1. the impact of a reduction of particle size on the extent of absorption of diosmin, giving a pharmacokinetic explanation to the better clinical efficacy observed with the micronized formulation, and 2. the use of accelerator mass spectrometry in conjunction with liquid scintillation counting in measurement of bioavailability in a human cross-over study comparing two drug formulations containing trace amounts of radioactivity.

Administration, Oral↗
PubMed1985

Sodium hypochlorite as a tissue solubilizing agent compatible with liquid scintillation counting.

The use of hypochlorite to prepare biological samples, containing incorporated radiolabeled molecules, for liquid scintillation counting was investigated. Hypochlorite both solubilized and decolorized a variety of animal tissues, but fat aggregates, cartilagenous tissue, and plant material resisted digestion. Although hypochlorite induced chemiluminescence, addition of acidified stannous chloride to the counting cocktail alleviated the spurious counts. The reported procedure, modified to suit particular experiments, may be applicable in a variety of situations where quantitation of biologically incorporated radiolabeled molecules is desired.

Animals↗
PubMed1988

Scintillation counting of 14C-labeled soluble and insoluble compounds in plant tissue.

A method is described for the liquid scintillation counting of 14C in plant tissues. Samples are fixed, in the scintillation vial, in a solution of ethanol and acetic acid (3:1) and decolorized with commercial bleach before the addition of scintillation liquid. The method was compared to other techniques of tissue oxidation or digestion and found to be equally effective at least with thin tissue samples. The technique is simple, rapid, and inexpensive and does not result in loss of 14C.

Carbon Radioisotopes↗
PubMed1978

A new assay for rapid measurement of MIF levels by 3H-labelled cells in liquid scintillation counting vials: statistical implications for the measurement of migration inhibition.

A new quantitative assay for migration inhibitory factor (MIF) employs 3H-labelled cultured mouse or human lymphoid cells migrating from capillary tubes. Capillaries filled with labelled cells are placed in liquid scintillation counting vials, along with the MIF-containing sample and are removed at the end of a five-hour incubation period. The residual, labelled cells which have migrated out of the tubes are solubilized and counted in a liquid scintillation counter. While cultured lymphoblast cells are routinely used in the assay, the method was checked against mouse and guinea pig peritoneal exudate cells in both the labelled cell technique and the conventional chamber assay. The assay is technically simple to perform and a useful tool for laboratory research purposes because of the short span of time needed to obtain the results. These advantages indicate a potential for automation and use of this assay in a clinical immunology laboratory. Statistical analysis of data from both assays demonstrated that the relative variation among replicates is lower in the labelled cell assay. The new assay also measured a significant difference between controls and MIF-containing samples when the migration index (MI) was greater than 80%. Criteria for significant inhibition of migration are discussed in regard to the use of analysis of variance (ANOVA) and other statistical procedures, and the inadequacy of a single measure, such as the MI, is discussed.

Animals↗
PubMed1993

Quantification of chemiluminescent DNA probes using liquid scintillation counting.

A novel method for quantifying chemiluminescent DNA probes is described. The method uses liquid scintillation counting to measure light emission from the alkaline phosphatase-catalyzed breakdown of the substrate PPD (3-(4-methoxyspiro[1,2-dioxetane-3,2'-tricyclo[3.3.1.1 (3.7[decan]- 4-yl)phenyl phosphate) on dot blot preparations. Serial dilutions of either pUC18 DNA or lambda DNA were hybridized with digoxigenin-labeled probes and detected using the method described. Light flux (luminescence) was linearly related to DNA concentration, typically with a coefficient of determination (r2) of 0.9 or better. Due to the stability of alkaline phosphatase and the long-lived luminescence of PPD in the Lumi-phos formulation, repetitive analyses of a given sample can be made for up to 20 h. The method can reliably detect 17 amol of DNA (30 pg pUC18DNA) with a coefficient of variation on replicate samples of 14%. Optimization experiments showed that 7% sodium dodecyl sulfate in the prehybridization and hybridization buffers resulted in the lowest background; the best combination of signal-to-noise ratio and reproducibility was obtained using Bio-Rad Zeta-Probe GT nylon membranes. Direct immersion of samples into a solution of substrate was found to give the most precise results and ensured that substrate limitation at high concentrations of alkaline phosphatase (i.e., higher DNA amounts) did not occur.

Adamantane↗
PubMed1999

Quantification of telomerase activity by direct scintillation counting.

An improved telomerase assay was developed that allows direct quantification of the enzyme activity by scintillation counting of the labeled telomerase product. The assay measures the incorporation of 32P-dGTP into telomeric repeats synthesized at the 3' end of a biotinylated primer. Telomerase reaction product is separated from the reaction mix by streptavidin-coated magnetic beads and counted. The assay can be used for quantitative studies of human telomerase and its inhibitors.

Biotin↗
PubMed1992

Integrated approach to surfactant environmental safety assessment: fast atom bombardment mass spectrometry and liquid scintillation counting to determine the mechanism and kinetics of surfactant biodegradation.

Fast atom bombardment mass spectrometry and liquid scintillation counting have been used to study the biodegradation of a novel cationic surfactant in live sludge. The rates of primary biodegradation and the extent of complete mineralization were determined. Furthermore, an intermediate degradation product was identified and its rates of formation and subsequent removal have been established. These data find utility in assessing the environmental safety of the surfactant and the accuracy of various environmental fate models.

Biodegradation, Environmental↗
PubMedDate not supplied

Standardization of 32P/33P and 204Tl by liquid scintillation counting.

Two solutions, one of 32P with a significant contribution of 33P, and another one of 204Tl were standardized by liquid scintillation counting in the frame of two intercomparison exercises organized by the BIPM in 2002. For the 32P solution, the counting efficiencies for 32P and 33P were obtained by the CIEMAT/NIST method. The individual contributions of 32P and 33P were determined by fitting a set of measurements to a function of the half-lives and counting efficiencies of both component nuclides. 204Tl was also standardized by the CIEMAT/NIST method using two counters, three scintillators, HiSafe 3, Insta-Gel Plus and Ultima-Gold, and two different kinds of samples. A total of 480 samples were measured over 45 days with results in full agreement within the uncertainties considered. The efficiency values are also compared to those used in the previous 204Tl intercomparison (1997).

Algorithms↗
PubMed1976

Liquid scintillation counting for measurement of tritiated uptake in lymphocyte transformation in vitro: a new direct-suspension procedure.

Liquid scintillation counting of trichloracetic acid extracts of [3H] TdR-labelled lymphocytes has been studied by a direct suspension method without previous solubilization. In this new method, mixing of the labelled powder in water suspension with Scintillator Emulsifying Mixture (SEM) results in a firm gel whose mechanical properties provide an heterogeneous sample ready for counting. Counting efficiency and stability of such samples are related to the amount of labelled cells. Comparative studies with standard hyamine procedure have shown that this simple and rapid method gives reliable results.

Animals↗
PubMed1983

Potential errors in body composition as estimated by whole body scintillation counting.

Vigorous exercise has been reported to increase the apparent potassium content of athletes measured by whole body gamma ray scintillation counting of 40K. The possibility that this phenomenon is an artifact was evaluated in three cyclists and one nonathlete after exercise on the road (cyclists) or in a room with a source of radon and radon progeny (nonathlete). The apparent 40K content of the thighs of the athletes and whole body of the nonathlete increased after exercise. Counts were also increased in both windows detecting 214Bi, a progeny of radon. 40K and 214Bi counts were highly correlated (r = 0.87, p less than 0.001). The apparent increase in 40K was accounted for by an increase in counts associated with the 1.764 MeV gamma ray emissions from 214Bi. Thus a failure to correct for radon progeny would cause a significant error in the estimate of lean body mass by 40K counting.

Adolescent↗
PubMed2005

Ultraviolet photolysis of urine for suppression of color quenching prior to liquid scintillation counting of tritium.

In order to reduce the color quenching in the measurement of tritium in urine by liquid scintillation counting , UV irradiation was applied to decompose the organic substances in the sample. Urine was decolorized under UV irradiation in the presence of hydrogen peroxide. As a result, color quenching was considerably suppressed and higher counting efficiency of tritium was obtained. This UV treatment made it possible to increase the urine content in the sample from 2 to 40% (v/v) without significant decrease of counting efficiency. Either higher sensitivity or shorter analysis time was achieved in the tritium measurement by the augmentation of urine content. When the measurement time was 30 min, the detection limit of tritium defined as 3s was 0.03 Bq/ml. At the expense of some sensitivity (set at a detection limit of 0.3 Bq/ml), the measurement time was shortened to 0.5 min. These results will make a great improvement to routine tritium monitoring as well as to emergency monitoring in mass tritium exposure.

Color↗
PubMed1977

Comparison of RNA and DNA synthesis, spontaneous and PHa induced, between blood lymphoid cells of newborn infants, older infants, and adults. A study of scintillation counting and by autoradiography.

Spontaneous and PHA induced RNA and DNA synthesis was measured qualitatively by autoradiography and quantitatively by scintillation counting in blood lymphoic cells of newborn infants, older infants, and adults. Spontaneous RNA synthesis was found in transitional cells, large phagocytic lymphoid cells and lymphocytes. Transitional cells and phagocytic lymphoid cells also synthesized DNA spontaneously. Quantitatively, spontaneous RNA synthesis was active in both newborn infants and in adults, but significantly less so in older infants. PHA stimulation for 18 h increased RNA synthesis significantly in blood lymphoid cells of newborn infants and adults, and to a much lesser but still significant degree in older infants. Spontaneous DNA synthesis was significantly greater in newborn infants than in older infants and adults. PHA stimulation for 18 h had no effect on thymidine incorporation in any of the groups studied.

Adult↗