Scintillation counting vials

As shown in Figure 3, our detectors came equipped with a cylindrical plastic cell about the size and shape of a scintillation counting vial into which a U-shaped tube had been drilled. When this cell has been packed with scintillation grade anthracene a flow cell quite satisfactory for aqueous systems is obtained. 

Step 3. Cool the sample to room temperature. Transfer an aliquot with a 10-mL pipette to a clean scintillation counting vial. 

Step 11. Elute the strontium from the column with two 5-mL portions of 0.5 M HN03. Collect the two eluents in a clean plastic container (a 20-mL liquid scintillation counting vial or a 50-mL centrifuge tube is suitable). 

Finally, elute the [ PjcAMP by adding 3 ml of 100 mM imidazole, pH 7.5, to the alumina columns and allow them to drip directly into 7-ml scintillation counting vials. Cap the scintillation vials and count using the P window of the scintillation counter for 1 min. 

The dimensions of the gcimma vial detectors are similiar to those of standard liquid scintillation counting vials currently in use, and accomodate samples up to 17 mm diameter by 50 mm long (Figure 1). 

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 efficiency of the cDNA probe synthesis is determined by scintillation counting of the flowthroughs from steps 9 and 11 5pL of each flowthrough are added to 5mL scintillation fluid in separate scintillation counter vials. The samples are counted on the P-channel, and the obtained counts are multiplied by a dilution factor of 20. Probes should yield a total of 5-25 x 10 cpm see Note 32). 

To extract the liberated fatty acids, 1.5 ml of 0.1 mM carbonate-bicarbonate buffer, pH 10.5 is added and the mixture is shaken for 10 s. Centrifugation for 45 min at 1500 xgin a swing-out rotor will separate the water from the lower organic phase. In a scintillation vial, 2 ml of the upper water phase are mixed with 50 pi of glacial acetic acid containing 500 pg ferric acid before the scintillation liquid is added (16 ml of Ecoscint toluene (7 1 volume). Liquid scintillation counting is done for 5 min and the LPL activity is calculated from the difference in counts between the blank and the sample vials [40]. 

The lowest Y value obtainable using the above-mentioned liquid scintillation counting systems is limited by the volume of the vial used (25 ml.). For lower Y values, a larger volume is necessary (3, 7). To determine the optimum volume, a system was designed as shown in Figure 1. A Teflon tube with a 5-cm. internal diameter was used as the container and reflector. Two Teflon sheets (0.3-mm. thick) closed both ends of the tube by two O-rings and two aluminum devices pressed... 

If the available scintillation counter does not have an adequate quench correction function, it may be necessary to process a non-radioactive fecal sample as described above and add an equivalent amount of the hexane extract to the counting vials for the starting sterol mix (from Section 2.1 or 2.2 above) so it is quenched similarly to the fecal samples. 

The concentration was further corrected for radiochemical purity according to the manufacturer s specifications because liquid scintillation counting measures the total sample activity and does not account for the presence of radiolabeled impurities. Stock solutions were stored at -15°C or -20° C in order to minimize sample loss due to hydrolysis. Injected sample solutions were prepared in 0.25 mL plastic vials by diluting stock solutions with buffer or deionized water and were also stored at -15° C or -20° C. 

An aliquot of the distilled and condensed tritium-containing water sample is prepared for LS counting by adding it to an LS cocktail in a counting vial. Also counted in the same batch are two other vials with scintillation cocktail, one with a standard tritium solution, and the other with a blank water solution. 

This method is laborious and expensive, as well as being irreversible after the standard has been added. With access to good scintillation counters, it is more usual to carry out measurements with an external standard in which a y emitting source is positioned dose to the stintillation vial. The y rays excite the solvent molecules and the resulting additional scintillation counts (which are also subject to quenching) are used for standardisation. 

C. P. Petroff, P. P. Nair, and D. A. Turner, Int. J. Appl. Radiat. Isot., 15 491 (1954). The Use of Siliconized Glass Vials in Preventing Wall Adsorption of Some Inorganic Radioactive Compounds in Liquid Scintillation Counting. 

For radioactivity measurements, in the range 3-5% acrylamide with 0.5% agarose, the gels are most easily sectioned by slicing segments with a microtome. The sections are then transferred one at a time from the cutting device to vials for liquid scintillation counting. 

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