Radioactive compound, quantity

The existence of bismuthine was first demonstrated by using a radioactive tracer, Bi (8). Acid treatment of a magnesium plate coated with Bi resulted in the hberation of a volatile radioactive compound. In subsequent experiments, magnesium bismuthide [12048-46-3], Mg Bi, was treated with acid the yield, however, was only one part of bismuthine for every 20,000 parts of bismuth dissolved. Attempts to prepare bismuthine by reduction of bismuth trichloride with a borohydride have not been particularly successful. Experimental quantities ate best prepared by disproportionation of either methylbismuthine [66172-95-0], CH Bi, or dimethylbismuthine [14381-45-4], C2H. Bi (7) ... 

To make these substrates suitable for biological assays, the introduction of functional groups that can be traced with the proper analytical techniques is essential. The use of radio-, fluorescent-, and biotin-labeled lipidated peptides has been reported. The synthesis of fluorescent substrates is chemically straightforward and allows for production of larger quantities than the enzymatic synthesis used for radiolabeled peptides and is thus preferred over the use of radioactive compounds. [1 21] Common fluorescent probes can be introduced by conjugation to a free functional group present in the peptide. The fluorescent moiety is... 

A variation of the use of standards is the method in which predetermined quantities of a standard radioactive compound are added to the solution. The fractions are collected, and, by plotting the counts of the fractions, the peak of interest can be identified. This method is especially useful in following cell metabolism of purine and pyrimidine analogs. A plot of the nucleotides in a cell extract of schistosomes containing 14C-labeled adenine and guanine nucleotides is shown in Figure 7.3.5... 

For a radioactive compound, the molar activity (the number of radioactive disintegrations per mole per unit time, or some quantity proportional to this) is directly proportional to the ratio of radioactive to stable isotope in the compound. Radioactivity can be measured with a precision of 1% or better, depending upon how much care one is willing to take. 

Many radioactive compounds can be used as tracers or indicators becanse they emit a characteristic radiation which allows their presence to be detected, even in very minute quantities. Chemical and biochemical reactions and many physical processes are largely insensitive to the difference in nuclei which exists between the stable and radioactive isotopes—in this case P and P. It is therefore possible to mix a small nnmber of radioactive atoms with the stable ones, and incorporate them in the same chemical compound. The emission of radiation from the radioactive species enables them to be detected and followed in the course of reactions which the given compound may undergo. 

In addition to the convertible Type A cabinet used in the Type B mode, there are two additional versions of the Class II Type B cabinet. These units differ from the Type A and B3 units mainly in the airflow velocities and proportion of air recirculated, as well as in certain other performance specifications. Class II Type B1 cabinetry allows a little more flexibility in working with volatile, toxic, or radioactive substances, since its exhaust is connected to an exhaust duct that exhausts the cabinet air directly outside the building (Figure 9.6). Because 70 percent of the circulating air in the cabinet is exhausted to the outdoors, most nonexplosive or nonflammable chemicals may be used safely in low concentrations. Microgram quantities of toxic, carcinogenic, or radioactive compounds may be handled in the Class II Type B1 cabinet, provided that the work is performed in the direct exhaust portion (behind the smoke split) of the work surface. 

It is important to note that since the amounts of radioactive material produced are so extremely small (some 10 % of the total is typical) it is usually necessary to add macro quantities—10-100 mg—of each compound expected to be present, in order to effect a good separation and to measure the chemical yield of the carrier. The yield measured is the radioactivity in each separated chemical species as a fraction of the total radioactivity in the sample, corrected to 100% chemical yield of each respective carrier. The term retention is commonly used to refer to the yield of the parent compound. This term has the disadvantage, however, of implying that the radioactive atom remained in the same molecule. Since it often appears that the molecule is only later reconstituted, the terms yield and parent yield are to be preferred. 

The chemistry of sulfur is a broad area that includes such chemicals as sulfuric acid (the compound prepared in the largest quantity) as well as unusual compounds containing nitrogen, phosphorus, and halogens. Although there is an extensive chemistry of selenium and tellurium, much of it follows logically from the chemistry of sulfur if allowance is made for the more metallic character of the heavier elements. All isotopes of polonium are radioactive, and compounds of the element are not items of commerce or great use. Therefore, the chemistry of sulfur will be presented in more detail. 

The comprehensive dedicated research ultimately made it possible to decode the patterns of labelling in almost any type of tritium labelled compound at low isotopic abundance (e.g., 3 x 10 4 to 3 x 10 2 per cent. 3H per site) with the aid of 3H-NMR directly, rapidly, reliably and non-destructive analytical means. Since, 1971, the 3H-NMR spectroscopy, utilizing only millicurie (mCi) quantities of radioactivity, emerged as a most useful analytical tool for the study of tritium labelled compounds. 

The most widely used technique for the separation of large quantities of radioactive material is that of solvent extraction. The principle of the method is that ideally the partition coefficient of a compound between two solvents does not depend on concentration in a given set of conditions. This was shown in an early paper of Graham and Sea-borg (35) who demonstrated that the partition coefficients of gallium and cobalt chlorides between ether and aqueous hydrochloric acid were the same for concentrations of lCTli molar (i. e. no added carrier) as for 1-6xl0 s molar. 

Robenidine, which was the major component in the excreta, represented about 10% of the extractable radioactivity in the soil. In terms of total carbon-14 residues in the soil, parent compound represented 2.0%. Metabolite 2, which was present only in trace quantities in the excreta, accounted for 21% of the extractable radioactivity or 4.2% of the total carbon-14 residues in the soil. This metabolite was also the only significant compound found in the water. Three other metabolites accounted for about 18% of the extractable radioactivity in the soil, namely, Metabolite 3, 5.3%, Metabolite 6, 7.6% and Metabolite 10, 4.9%. Polar material which was not resolved from the origin represented 25% of the extractable radioactivity in the soil. 

Most of the radioactive actinium isotopes that are produced in nuclear reactors are in milligram quantities. There are not many common compounds. 

Protactinium is a relatively heavy, silvery-white metal that, when freshly cut, slowly oxidizes in air. AH the isotopes of protactinium and its compounds are extremely radioactive and poisonous. Proctatinium-231, the isotope with the longest half-life, is one of the scarcest and most expensive elements known. It is found in very small quantities as a decay product of uranium mixed with pitchblende, the ore of uranium. Protactiniums odd atomic number (gjPa) supports the observation that elements having odd atomic numbers are scarcer than those with even atomic numbers. 

The chemical composition of the compounds, until now characterized predominantly by X-ray diffraction methods in analogy to lanthanide or actinide compounds, is increasingly being determined by standard analytical procedures. These methods (e.g. coulometry, spectrophotometry) have to be adjusted to the quantity of material available and effects of radioactive decay have to be taken into account. As with metals, chemical... 

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