Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Scintillation Counting”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed1997

Determination of 226Ra and 224Ra in drinking waters by liquid scintillation counting.

A method for the determination of Ra-isotopes in water samples has been developed. Ra is coprecipitated with Ba as sulphate. The precipitate is then dissolved with EDTA and counted with a liquid scintillation system after mixing with a scintillation cocktail. The study of the temporal evolution of the separated activity gives the isotopic composition of the sample, i.e. the 224Ra and 226Ra contribution to the total activity. The method has been applied to some Spanish drinking waters.

Chemical Precipitation↗
PubMed1985

Determination of 99Tc in urine by liquid scintillation counting to evaluate internal contamination.

A practical method is described which allows the radiochemical determination of 99Tc in urine. The radionuclide is recovered as tetraphenylarsonium pertechnetate by coprecipitation with tetraphenylarsonium perchlorate and its activity is counted by the liquid scintillation technique. The lower limit of detection, assumed equal to three standard deviations of the blank activity, is about 2 pCi in 50 ml of urine and permits an evaluation of an internal contamination of one investigation level even four months after intake. The urinary excretion function of 99Tc is calculated from experimental data reported in the literature for 99mTc and is used to establish derived investigation levels on the basis of annual limits on intake recommended by the International Commission on Radiological Protection. The illustrated method is sensitive enough to perform accurate evaluations every three months, a frequency suitable for radiological protection of workers.

Humans↗
PubMed1989

Low background scintillation counting.

Counting radioactive samples with Beckman Instrument's Ready Caps, using a restricted energy window, LL-UL = 400-1000, resulted in machine backgrounds of under 2 cpm and efficiencies of counting relative to liquid scintillation cocktails (LSC) of 51%, 65%, 57%, 62%, and 1% for 32P, 125I, 14C, 35S and 3H, respectively. Signal-to-noise ratios from a quantitative molecular hybridization technique were increased 8-10 fold. There may be a general application for this product in experiments yielding low amounts of radioactivity in liquid samples.

Animals↗
PubMed1987

Automated high performance liquid chromatography and liquid scintillation counting determination of pesticide mixture octanol/water partition rates.

Two novel methods are reported for measuring octanol/water partition rates of pesticides. A liquid scintillation counting (LSC) method was developed for automated monitoring of 14C-labeled pesticides partitioning in biphasic water/octanol cocktail systems with limited success. A high performance liquid chromatography (HPLC) method was developed for automated partition rate monitoring of several constituents in a pesticide mixture, simultaneously. The mean log Kow +/- SD determined from triplicate experimental runs were for: 2,4-D-DMA (2,4-dichlorophenoxyacetic acid dimethylamine), 0.65 +/- .17; Deet (N,N-diethyl-m-toluamide), 2.02 +/- .01; Guthion (O,O-dimethyl-S-(4-oxo-1,2,3-benzotriazin-3(4H)-ylmethyl) phosphorodithioate), 2.43 +/- .03; Methyl-Parathion (O,O-dimethyl-O-(p-nitrophenyl) phosphorothioate), 2.68 +/- .05; and Fenitrothion (O,O-dimethyl O-(4-nitro-m-tolyl) phosphorothioate), 3.16 +/- .03. A strong positive linear correlation (r = .9979) was obtained between log Kow and log k' (log Kow = 2.35 (log k') + 0.63). The advantages that this automated procedure has in comparison with the standard manual shake-flask procedure are discussed.

Autoanalysis↗
PubMed1980

The effects of glutaraldehyde and formaldehyde fixation on the retention and subcellular location of [3H]5-hydroxytryptamine in rabbit platelets: a study using liquid scintillation counting and E.M. autoradiography.

The retention and loss of [3H]5-hydroxytryptamine (5-HT) from rabbit platelets during fixation was studied using liquid scintillation counting and quantitative electron-microscopic autoradiography. The results were at variance with previously reported data on human platelets. Following treatment of the platelets with either 2.0% formaldehyde or 2.5% glutaraldehyde for 2 min or 1 h it was found that a significantly increased proportion of the radioactivity was lost from treated as compared with untreated platelets. Using a method of analysis which accounts for cross-scatter of decay particles between cell compartments, electron-microscopic autoradiography revealed that 50% of the radioactivity following incubation of platelets with [3H]5-HT was associated with dense bodies and 30% in the cytoplasm when fixation was in formaldehyde or glutaraldehyde. The only major difference in the labelling pattern was that whereas glutaraldehyde appeared to retain no activity in the surface connected system the latter contained 12% of total retained activity following fixation with formaldehyde.

Aldehydes↗
PubMed1986

Uptake, distribution and elimination of 3H-gentamicin in different organs of the rat as determined by scintillation counting.

Radioactivity attained in different tissues at different times after a single intraperitoneal injection of 3H-gentamicin into male rats was determined using scintillation counting. After about 30 min. kidney cortex demonstrated 3- to several hundred-fold greater radioactivity than other tissues. Gentamicin was released from kidney medulla and the urinary bladder relatively rapidly, whereas the radioactivity in kidney cortex and thoracal cartilage was maintained for at least 6 hrs.

Animals↗
PubMed1960

Liquid scintillation counting of aqueous solutions of carbon-14 and tritium.

A method is reported whereby aqueous solutions containing weak beta emitters are dispersed as stable emulsions in liquid scintillator counting solutions. This permits the routine counting, with about 10-percent efficiency, of large numbers of samples containing tritium. Self-absorption does not present a problem when less than 5 percent aqueous phase is present.

Carbon↗
PubMed1997

Improvement of the Eakins and Brown method for measuring 59Fe and 55Fe in blood and other iron-containing materials by liquid scintillation counting and sample preparation using microwave digestion and ion-exchange column purification of iron.

The simultaneous measurement of 59Fe and 55Fe in whole blood by liquid scintillation counting by the Eakins and Brown (EB) method is extensively used in iron absorption studies. The EB method requires many steps which increase the chances of error and decrease its sensitivity. We describe two modifications to the above method consisting of microwave digestion and column purification of iron. This "New Method" (NM) is simpler and more precise, and sensitive than the EB method. Counting efficiencies with the NM are similar for 59Fe (75%) as with the EB method but are better for 55Fe (29% for NM vs 22%), and cross counting from 59Fe into the 55Fe window is lower with the NM (3.7-4.5%) than with the EB method (10-12%). For the NM, recoveries of radioactive blood samples, in relation to processed standards ranged from 100 to 103% for 59Fe and 101 to 113% for 55Fe. For the EB method, recoveries ranged from 94 to 99% for 59Fe and from 88 to 93% for 55Fe. Even with very low counts, average intrarun CV with the NM was lower than 5.4% for either isotope, while it was as high as 10.0% for 55Fe with the EB method.

Animals↗
PubMed2000

A validation study comparing accelerator MS and liquid scintillation counting for analysis of 14C-labelled drugs in plasma, urine and faecal extracts.

A comparison has been made between accelerator mass spectrometry (AMS) analysis and liquid scintillation counting (LSC) of plasma, urine and faecal samples containing 14C-labelled drugs. In an in vitro study in which human plasma was spiked (the term spiked is used in Section 2.6) with 14C-Fluconazole (14C-FL) over a concentration range of 0.1-2.5 dpm/ml, a correlation coefficient of 0.999 was determined for AMS analysis versus extrapolated LSC data. No significant day to day (or inter-day)variation was seen (P < 0.05 by ANOVA). Coefficients of variation for these analyses ranged from 2.68 to 6.50%. In vivo studies in which rats were given a high (11.5 microCi/kg) or low (18.1 nCi/kg) radioactive dose (to model an exposure of 0.9 microSievert to man) of 14C-Fluticasone propionate(14C-FP) showed that there was also a good correspondence between AMS and LSC data. A mass balance study in a single the faeces by 96 h; less than 1% of the administered dose was excreted in the urine. The limit of reliable measurement of drug related material, above background concentrations, by AMS analysis in this study was approximately 0.1 dpm/ml for plasma, 0.01 dpm/ml for urine without any sample extraction or concentration and 0.01 dpm/ml for faecal extracts. The data reported here demonstrate that AMS is an ultrasensitive and reliable method for analysing 14C-labelled drugs in human and animal body fluids.

Animals↗
PubMedDate not supplied

Serious complications in the liquid scintillation counting analysis of mercury-203.

The decrease in the count rate of mercury-203 as calculated from its half-life is approximately 0.06% per hour. In actual practice using liquid scintillation counting, this decrease can be far greater. It is shown that fluorescence, adsorption, and chemical reduction followed by volatilization are not responsible for this apparent loss of activity. The origin of the phenomenon is shown to be precipitation in the short term (24 h) followed by surface adsorption of the precipate in the longer term (greater than 2 days).

Chemical Precipitation↗
PubMed1987

Complete extraction in a form suitable for liquid scintillation counting of tritium-labeled proteins from polyacrylamide gels.

Large (200 mm3) slices of polyacrylamide gels crosslinked with N,N'-diallyltartardiamide which contain tritium-labeled protein are readily solubilized in periodic acid for liquid scintillation counting of radioactivity, but the apparent recovery of label never exceeds 82%. Extraction of the slices with two commercial solubilizers at 60 degrees C gave recoveries of 82-90% which were not improved by prolonged incubation. Treatment of the slices at ambient temperature with 1.0 ml of 2% sodium periodate for 30 min followed by the addition of 0.7 ml of aqueous tetrabutylammonium hydroxide (40% w/v) gives solutions which can be immediately counted at 35% efficiency with low background and with 100% recovery of tritiated protein

Electrophoresis, Polyacrylamide Gel↗
PubMed1995

Determination of quinapril and quinaprilat by high-performance liquid chromatography with radiochemical detection, coupled to liquid scintillation counting spectrometry.

Quinapril and quinaprilat concentrations were determined in perfusate, urine, and perfusate ultrafiltrate using a specific and sensitive reversed-phase high-performance liquid chromatographic procedure with radiochemical detection, coupled to liquid scintillation counting spectrometry. Quinapril and quinaprilat were measured in perfusate and urine after pretreatment with acetonitrile and subsequent centrifugation. Perfusate ultrafiltrate was used as collected. Two quinapril diketopiperazine metabolites, PD 109488 and PD 113413, were separated chromatographically from quinapril, quinaprilat, and from each other. Assay performance for quinapril and quinaprilat was assessed by examining precision and accuracy of the assay over four days. Using a 100-microliters sample volume, the limit of quantitation for both 3H-quinapril and 3H-quinaprilat (sp. act. approximately 2.0 muCi/micrograms) was 1 ng/ml.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1988

Radio high-performance liquid chromatographic determination of 14C-labelled LF 2-0254, A 1,4-dihydropyridine calcium antagonist, in rat and dog plasma using off-line liquid scintillation counting.

LF 2-0254 is a 1,4-dihydropyridine calcium antagonist with a slow onset of action. The pharmacokinetics of [14C]LF 2-0254 were studied in rats and dogs. A sensitive high-performance liquid chromatographic method using liquid scintillation counting was developed for the quantitation of labelled LF 2-0254 in plasma. The peak height of the internal standard in the chromatogram was measured by UV detection and the mobile phase containing the chromatographic peak of [14C]LF 2-0254 was collected and counted for radioactivity. The concentration of labelled drug in the plasma was then determined using a calibration graph constructed from the determination of [14C]LF 2-0254 of known specific activities. The limit of determination was dependent on the specific activity of the drug administered. This method permits the measurement of the radioactive drug in biological fluids.

Animals↗
PubMed1995

[Comparative analysis of two diffusion methods for radon Rn-222 estimation in atmospheric air by means of gamma ray spectrometry and liquid scintillation counting].

The comparative measurements of radon Rn-222 concentration in indoor air of some buildings and in radon labour chamber have been conducted using two different diffusions methods. The results of parallel measurements using radon charcoal detectors and gamma-rays spectrometry with liquid alpha scintillation counting (Pico-Rad) have been presented. It was concluded that both methods offer the similar measurements possibilities of radon concentrations in the air from about 30 Bq/m3 to about 600 Bq/m3 with the real average divergence between both methods of about +/- 11%.

Air Pollutants, Radioactive↗
PubMedDate not supplied

2003: a centennial of spinthariscope and scintillation counting.

In 1903 W. Crookes demonstrated in England his "spinthariscope" for the visual observation of individual scintillations caused by alpha particles impinging upon a ZnS screen. In contrast to the analogue methods of radiation measurements in that time the spinthariscope was a single-particle counter, being the precursor of scintillation counters since. In the same period F. Giesel, J. Elster and H. Geitel in Germany also found that scintillations from ZnS represent single particle events. This paper summarises the historical events relevant to the advent of scintillation counting.

Journal Article↗
PubMed1981

Photoactivated zinc silicate in thin layer chromatography plates: a potential cause for error in liquid scintillation counting.

Thin layer chromatography plates impregnated with fluorescent indicator permit easy identification of many compounds by exposure to ultraviolet light. Exposure of zinc silicate treated plates to ultraviolet light (254 nm) for 30 seconds induced photoluminescence which persisted at significant levels for longer than 24 hours. This artifact significantly interfered with radioactivity quantitation in three commercially available liquid scintillation solutions. Chromatography plates impregnated with calcium silicate demonstrated insignificant ultraviolet light induced photoluminescence. The use of 14C rather than 3H-radiolabeled compounds, protecting the plate with aluminum foil when visualizing reference compounds with ultraviolet light, and heating the photoactivated plate to accelerate disappearance of the photoluminescence minimized the error in liquid scintillation counting.

20-Hydroxysteroid Dehydrogenases↗
PubMed1998

Analytical performance of accelerator mass spectrometry and liquid scintillation counting for detection of 14C-labeled atrazine metabolites in human urine.

Accelerator mass spectrometry (AMS) has been applied to the detection of 14C-labeled urinary metabolites of the triazine herbicide, atrazine, and the analytical performance of AMS has been directly compared to that of liquid scintillation counting (LSC). Ten human subjects were given a dermal dose of 14C-labeled atrazine over 24 h, and urine from the subjects was collected over a 7-day period. Concentrations of 14C in the samples have been determined by AMS and LSC and range from 1.8 fmol/mL to 4.3 pmol/mL. Data from these two methods have a correlation coefficient of 0.998 for a linear plot of the entire sample set. Accelerator mass spectrometry provides superior concentration (2.2 vs 27 fmol/mL) and mass (5.5 vs 54,000 amol) detection limits relative to those of LSC for these samples. The precision of the data provided by AMS for low-level samples is 1.7%, and the day-to-day reproducibility of the AMS measurements is 3.9%. Factors limiting AMS detection limits for these samples and ways in which these can be improved are examined.

Adult↗