Scintillation counters, liquid

A liquid scintillation counter. This instrument is used to detect radiation and measure disintegrations per minute quickly and accurately. 

Linear molecule A triatomic molecule in which the bond angle is 180° examples include BeF2 and C02,176 Linear polyethylene, 612 Liquid scintillation counter, 518 Liquid-vapor equilibrium, 253-254q boiling point, 230-231 critical pressure, 231-232 critical temperature, 231-232 symbol, 227... 

The sampling of solution for activity measurement is carried out by filtration with 0.22 pm Millex filter (Millipore Co.) which is encapsuled and attached to a syringe for handy operation. The randomly selected filtrates are further passed through Amicon Centriflo membrane filter (CF-25) of 2 nm pore size. The activities measured for the filtrates from the two different pore sizes are observed to be identical within experimental error. Activities are measured by a liquid scintillation counter. For each sample solution, triplicate samplings and activity measurements are undertaken and the average of three values is used for calculation. Absorption spectra of experimental solutions are measured using a Beckman UV 5260 spectrophotometer for the analysis of oxidation states of dissolved Pu ions. 

Uniformly labeled C-8-D with a specific activity of 2.99 juc/mg was administered orally to pregnant females at 2 /xg/kg/day from 6-15 days of gestation. Three females were sacrificed on alternate days during days 6-20 of pregnancy. Triplicate samples of fetus, placenta, blood, brain, abdominal fat, and sartorius muscle were procured from each female. The samples were dissolved in 1 ml of Soluene (Packard Instruments) to which 15 ml of Aquasol were added. Each sample vial was counted for 30 min in a Nuclear Chicago Mark I liquid scintillation counter. 

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. 

Figure 2. Thin-layer radiochromatogram of urine (100 il) from rats injected with labeled PbTx-3. TLC plates were developed in two sequential solvent systems chloroform ethyl acetate ethanol (50 25 25 80 10 10). Radioactive zones were scraped and counted in a liquid scintillation counter. Native PbTx-3 runs at 13 cm.

The counting equipment used to establish quantitation is radioassay and radioimmunoassays may be either a gamma counter or a liquid scintillation counter depending upon the isotope being used. Most assays use as a label and require a... 

Tritiated or " C-tagged hydrocarbons (including tritium gas) can be measured by using a liquid scintillation counter or a gas proportional counter [1717,1718]. 

Mnk assay (using S6peptide as substrate) Each reaction contains 20 1 of immunoprecipitated or purified recombinant Mnk, as described previously, and S6 peptide (KEAKEKRQEQIAKKRRLSSLRASTSKSESSQK, final concentration = 200 pM) in kinase buffer. To initiate the reaction, 6 p of the following mix is added 5 pi 5x kinase buffer, 0.25 pi 10 mM ATP, 1 pCi [7 32P]ATP, and H20. Reactions are carried out in an orbital shaker at 30° and 900 rpm, for example, for 20 min (Mnkl) or for 5 min (Mnk2) and stopped by spotting 20 pi of the reaction mixture onto P81 paper. The filters are washed in 1% orthophosphoric acid three times. The radioactivity is determined by using a liquid scintillation counter. 

Radioactivity measurement The radioactivities of lead isotopes and their decay products were measured with TRICARB 3380 liquid scintillation counter (Packard Inc.). The radioisotopes concerned, and their decay charateristies are shown in Figure 2. In the case of the direct method, the absolute radioactivity can be obtained by the integral... 

Homma, Y. and Y. Murakami, Study on the Applicability of the Integral Counting Method for the Determination of Ra in Various Sample Forms Using a Liquid Scintillation Counter,. 1. Radioanal. Chem. 36 173-184 (1977). 

Murakami, Y. and K. Horiuchi, Simultaneous Determination Method of Radon-222 and Radon-220 by a Toluene Extraction-Liquid Scintillation Counter, J. Radioanal. Chem. 52(2) 275-283, (1979). 

C-labelled cholesterol was used to test the recovery of 5-100 pg of faecal sterols from seawater (labelled coprostanol not being available). The radioactivity of the samples and eluates was measured by a two-channel liquid scintillation counter. Percentage recovery was calculated on the basis of the amount of labeled material recovered in the acetone eluant. The results indicate that column extraction efficiency is not adversely affected by the salinity of the water samples, i.e., in the range 95-97%. 

Liquid scintillation counters are highly efficient for low CL intensities and consist of two photon-counting channels provided with a variable discriminator. The sample is placed between these two detectors to ensure a high optical efficiency. The discriminator is adjusted to allow photon impacts to be transmitted and small background noise pulses to be rejected. As disadvantages they suffer from saturation errors and provide nonlinear relationships between the CL intensity and the total counts. 

Capsules were equilibrated with a tracer solution overnight. A capsule pellet (0.2-0.5 ml) was then placed in 5 ml test buffer (PBS or RPMI-1640 medium, Gib-co/BRL, New York, NY) on a shaker and a 0.2-ml aliquot was immediately sampled by a screen-protected pipette with further samples being taken over the next 700 s. The tracer quantity was assayed using the methods described below. A final sample was taken after the capsules has been in contact with the buffer for several hours (equilibrated tracer quantity) and the increment to the tracer concentration at each time was calculated. From the progress of tracer to equilibrium on a semilog plot a slope denoted as the zero -order rate flux constant was obtained and has been used as a measure of capsule permeability. [3H] -Glucose (580 daltons),insulin (6.2 kDa), and ovalbumin (45 kDa) have been used as tracers. Radioactivity was measured by means of a Packard 2000CA Liquid Scintillation Counter (Packard Instruments,... 

During a study of the biosynthesis of pectin substances, a sensitive micromethod for the assay of pectinesterase activity was developed111 that uses a biosynthetically prepared [14C] methyl-labelled pectin as the substrate after enzymic de-esterification, the substrate remaining is precipitated with an excess of methanol and, after centrifugation, the [14C]methanol present in the supernatant liquor is counted in a liquid scintillation counter in order to assess the pectinesterase activity. 

Another method is based on the same principle,112 in which the [14C]labelled methyl ester of D-galacturonan is prepared by esterification of pectic acid with [,4C]diazomethane. In the course of the enzymic de-esterification, aliquots are removed, and the unreacted substrate is precipitated with acidified ethanol or 1-propanol. After centrifugation, the labelled methanol in the supernatant liquor is determined in a liquid scintillation counter. An advantage of this method lies in the possibility of using, as substrates, short-chain oligo-D-galactosiduronates partially esterified with [14C]methanol. These substrates, beginning with the trisaccharide, are not soluble in 1 4 80% phenol-diethyl ether, which is used for the extraction of enzymically released, labelled methanol. 

Plasma levels of dobutamine hydrochloride are determined by reaction of the drug with 3H-methyl-S-adenosylmethionine in the presence of catechol O-methy1-transferase. The radioactivity of the labeled methyl derivative is determined by a liquid scintillation counter using an external standard. The final recovery of added dobutamine as 3H-CH3-dobutamine is 24.9 1.3% in the range of 2 to 170 ng/ml (4). When 14C-dobutamine is administered the samples are counted by a double isotope method. 

Jensen and Hvitved-Jacobsen (1991) developed a direct method for the determination of the air-water oxygen transfer coefficient in gravity sewers. This method is based on the use of krypton-85 for the air-water mass transfer and tritium for dispersion followed by a dual counting technique with a liquid scintillation counter (Tsivoglou et al 1965,1968 Tsivoglou andNeal, 1976). A constant ratio between the air-water mass transfer coefficients for dissolved oxygen and krypton-85 makes it possible to determine reaeration by a direct method. Sulfur hexafluoride, SF6, is another example of an inert substance that has been used as a tracer for reaeration measurements in sewers (Huisman et al., 1999). 

The activity of the polymers was determined in toluene solution with Koch-Light KL.356 xylene-based scintillator in 4 ml glass vials, at an efficiency of 24% for tritium and 75% for 14C by means of an IDL liquid scintillation counter type 6012. 

Materials Required Schwartz-Mann-H3 Cortisol RIA-Kit liquid scintillation counter, centrifuge. 

The contents of the scintillation vial are mixed thoroughly, and the radioactivity is measured in a Liquid Scintillation Counter for 10 minutes,... 

The samples are assayed for 3H-activity in a liquid scintillation counter, and... 

Weak beta radiation and alpha particles often cannot penetrate the covering material but the use of a scintillant, which, together with the sample, will dissolve in a suitable solvent, enables a similar technique to be used. Liquid scintillation counters usually consist of two light-shielded photomultiplier... 

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. 

Another possibility of quantification is to cut the bands of interest and counting in a liquid scintillation counter after mincing the gel pieces. 

The examples for radioactive labeling by phosphorus-32 ( P) and iodine-125 ( 1) in this chapter were chosen for two reasons on one hand, they are relatively easy to do, and on the other hand, the measurement of radioactivity is simple. is counted in water in a liquid scintillation counter by measuring the Cerenkov radiation and is measured in a gamma counter. Both isotopes may be detected also by autoradiography. A further advantage of both isotopes is their short half-life, which eases the disposal of nuclear waste. 

Rackbeta 1216 and 1218 liquid scintillation counters (LKB Wallac, Turku, Finland). Counting was continued for 5 min or until 5000 counts. Statistical significance of the differences was tested using Mann-Whitney s U test. / <0.05 was considered to be a statistically significant difference. 

Separation of radioactively labeled substrate and product on diethylaminoethyl (DEAE) cellulose 14C-galactose is eluted by H20, 14C-galactose-l-phosphate is retained 14C-galactose-l-phosphate is subsequently eluted by 100 mM HC1. Determination of eluted radioactivity in a liquid scintillation counter (/1-counter) [5,... 

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