Radioactivity, use

In the carbon-14 expts, HMX/RDX product was isolated qualitatively, separated Into its components, and each component assayed for carbon-14 beta radioactivity using a liquid scintillation counting technique (Ref 11). DPT-l4C was isolated as an intermediate product from the reaction mixt and similarly radioassayed. For the nitrogen-15 tagged AN expts, HMX and RDX were assayed mass spectrometrically for i5N/i4N ratios from which atom %1SN contents were calcd. In die course of these expts, each tagged species was added initially and also at subsequent stages of the reaction process. The important observations and results are summarized as ... 

The element may be determined from its radioactivity using tracer techniques. Isotopes of the element may be identified by mass spectrometry. 

Table 9.35 Natural radioactivity used for age dating in terrestrial geological samples and meterorites. 

Thermal polylysine also catalyzes the formation of a-ketoglutaric acid from glutamic acid with CuCl25). A reaction mixture of lysine-rich proteinoid (20 mg), 14C(U)-l-glutamate (0.1 mM), and CuCl (0.1 mM) in 6 ml of Britton-Robinson buffer (pH 7.0) is incubated at 37.5 °C for 2 hours. More than 40 % of the radioactivity used is recorded in a-ketoglutaric add by paperchromatography of the reaction mixture25 . Free lysine and Leuehs poly-L-lysine have no activity 2S). The reaction obeys Michaelis-Menten kinetics at optimum pH 7.0 25). 

Count the radioactivity using a liquid scintillation counter. 

Antoine Henri Becquerel discovered radioactivity using uranium salts. 

ADME Since metabolism and formation of active metabolites are not a concern for unmodified biopharmaceuticals, mass balance studies are uninformative. Tissue concentration of radioactivity using radioactive proteins is also difficult to interpret due to unstable radiolabel linkage, rapid in vivo catabolism, and recycling of radiolabeled amino acids into non-drug-related proteins/peptides. 

Figure 10. The Cross Sectional Profiles of the Reactor Gases Radioactivity (Using Kr-85 In Fuel Gas) at Reactor Port Locations (HAF Data)...

The immunoadsorbent suspension at 1 mg of cellulose per milliliter is washed three times and then doubly diluted to 1/64. The labeled antibody is diluted to the region of 5000 cpm in 100 /til and added in this volume in quadruplicate to 50-/al aliquots of immunoadsorbent suspension in polyethylene tubes (Beckman EET or Sarstedt 46/6). The reaction is carried out for 20 min at room temperature. After centrifugation for 1 min in a Beckman Microfuge (model B), IOO-/1I aliquots of supernatant are removed to counting tubes (e.g., Luckham LP3) using a diluter (e.g., LKB model 2075). In order to measure the total radioactivity used, four tubes are set up containing NIGP buffer instead of immunoadsorbent. 

Figure 5 Graph demonstrating in vitro reproducibility of the emitted dose for a radiolabeled drug powder inhaled at two different inspiratory flowrates. Although the mean dose of drug and radioactivity varied between study days, the coefficient of variation for the emitted doses of drug or radioactivity on each study day was low. The amount of radioactivity used in the labeling of the powder varied with the specific activity of the 99mTc04 supply on each labeling day [86].

Differentiate between natural and induced radioactivity. Use the periodic table to identify the locations of those elements that are the result of induced radioactivity. 

There are several methods for the quantification of radiochromatograms. Depending on the available instrumentation, the resolution of analysis will vary, and the amount of radioactivity used for analysis will differ considerably. In any case, the results of measurements are used to calculate the radiochemical purity of a radiopharmaceutical (percentage) as the ratio between the radioactivity corresponding to the main component, divided by the total recovered radioactivity of the chromatogram ... 

The mechanism of this dehydrogenation was investigated by studying the distribution of radioactivity using phenyP C-hydrazine, whereby it was shown that no intramolecular oxido-reduction takes place, but rather, that the enediamine form causes hydrogenation of the free phenyl-hydrazine present in the reaction mixture, to yield aniline and ammonia. This mechanism was criticized by Weygand when this work was presented, and the problem of intermolecular or intramolecular oxido-reduction still awaits settlement. 

It might be necessary to take samples of, e. g. the total amount of radioactivity used and liquid or solid waste. Take them at appropriate times to complete your radioactivity records. 

Add 1 mL of PCS scintillant to the solubilised pellet and determine the radioactivity using a liquid scintillation counter (31, 32). 

There are no tritium background signals at the levels of radioactivity used for NMR analysis. 

Radioligands represent the radioactive forms of endogenous neurotransmitters, neuromodulators, hormones or enzyme substrates, or synthetic compounds that interact with the binding sites on receptors or enzymes. Ligands are made radioactive using a number of isotopes (e.g., H, or... 

In fact, even the very low neutron flux in the upper atmosphere could he measured hy radioactivity using this technique hy Von Halban Jr et al. (1939) who used ethyl bromide as a target material for the production of the radioisotope from (n,y) reaction. 

After lyophilization, the dry material is assayed for radioactivity using liquid scintillation counting and the water content is calculated. A comparison was made between the tritium method and the gravimetric method. The sensitivity of the tritium method was stated to be 1 pg of water it measures the water content of 1 mg of dry material with an accuracy of 0.1%. It was noted that small amounts of tritium were found in the nontest ampoules after lyophilization. In addition, tritium oxide was used to measure the exchange of water molecules between stopper and material. Kassai and Sikos stated that the product distributed into the vial takes up water from the stopper until a state of equilibrium ensues. ... 

Radioactive waste minimisation may also be obtained by means of a reduction of the radioactivity using a Partitioning and Transmutation (P T) strategy [2]. 

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