Phosphorus radioactive isotopes

Also present in the first test tube is a synthetic analog of ATP in which both the 2 and 3 hydroxyl groups have been replaced by hydrogens This compound is called 2 3 dideoxyadenosme triphosphate (ddATP) Similarly ddTTP is added to the second tube ddGTP to the third and ddCTP to the fourth Each tube also contains a primer The primer is a short section of the complementary DNA strand which has been labeled with a radioactive isotope of phosphorus ( P) When the electrophoresis gel is examined at the end of the experiment the positions of the DNAs formed by chain extension of the primer are located by a technique called autoradiography which detects the particles emitted by the P isotope... 

Phosphorus has only one stable isotope, J P, and accordingly (p. 17) its atomic weight is known with extreme accuracy, 30.973 762(4). Sixteen radioactive isotopes are known, of which P is by far the most important il is made on the multikilogram scale by the neutron irradiation of S(n,p) or P(n,y) in a nuclear reactor, and is a pure -emitter of half life 14.26 days, 1.7()9MeV, rntan 0.69MeV. It finds extensive use in tracer and mechanistic studies. The stable isotope has a nuclear spin quantum number of and this is much used in nmr spectroscopy. Chemical shifts and coupling constants can both be used diagnostically to determine structural information. 

C15-0124. Phosphorus-32 is a radioactive isotope that decomposes in a unimolecular first-order process. The... 

Radioactive isotopes provide a very convenient way of monitoring the fate or metabolism of compounds that contain the isotopes. When used in this way, the isotope is described as a tracer and compounds into which the radioactive atom has been introduced are said to be labelled or tagged. The labelled molecules need only comprise a very small proportion of the total amount of the unlabelled radioactive substance because they act in the same way as the non-radioactive substance but can be detected very much more easily. The varied applications of tracers in biochemistry range from studies of metabolism in whole animals or isolated organs to sensitive quantitative analytical techniques, such as radioimmunoassay. Phosphorus-32 is used in work with nucleic acids, particularly in DNA sequencing and hybridization techniques. In these instances the isotope is used as a means of visualizing DNA separations by autoradiographic techniques. 

The first of these equations shows that the result of the nuclear reaction in which aluminum is bombarded with or-partides is the emission of a neutron and the production of a radioactive isotope of phosphorus. The second equation shows the radioactive disintegrations of the latter to yield a stable silicon atom and a positron. Continuation of this line of investigation by several research groups confirmed that radioactive nuclides are formed m many nuclear reactions. 

For example, it was demonstrated by such methods that phosphorus assimilated from the soil by tomato plants tends to concentrate in the stems and certain parts of the leaves. Similarly, radioactive zinc was used to show that this element localizes in the seeds of tomatoes. The rate of absorption of iodine by the thyroid gland was established by the use of radioactive iodine this and related work did much to add to the understanding of the diagnosis and treatment of goiter. These and many similar uses of radioactive isotopes show that these substances have been of inestimable value in the study of the mechanism of chemical reactions, problems relating to plant and animal metabolism, and the diagnosis and treatment of diseases. 

Sometimes the nucleus can be changed by bombarding it with another type of particle. This is referred to as induced radioactivity. In 1934, Irene Curie, the daughter of Pierre and Marie Curie, and her husband, Frederic Joliot, announced the first synthesis of an artificial radioactive isotope. They bombarded a thin piece of aluminum foil with ot-particles produced by the decay of polonium and found that the aluminum target became radioactive. Chemical analysis showed that the product of this reaction was an isotope of phosphorus. 

The product of this reaction, P °, was the first man-made radioactive isotope reported and also the first positron emitter. By tracing the radiations, it could be shown that the positron-emitter produced in the reaction had the chemistry of phosphorus. In this case, then, the heavier product could be identified by its chemistry even though only very tiny amounts were formed. 

We know that nuclear weapons are capable of mass destruction, yet radiation therapy, shown in Figure 4.18, is a proven cancer fighter. Smoke detectors, required by law in all homes, rely on the radioactive decay of americium-241. The human body itself is radioactive, due to the presence of radioactive isotopes including carbon-14, phosphorus-32, and potassium-40. Most people view radioactivity and nuclear reactions with a mixture of fascination, awe, and fear. Since radioactivity is all around us, it is important to understand what it is, how it arises, and how we can deal with it safely. 

A special case in Table III is the element phosphorus, which is often of interest in polymers. Its radioactive isotope P-32 emits hic i-energy beta-rays but no gamma-rays. We detect it with a beta spectrometer enplcying a 0.6 cm thick plastic scintillator coupled to a photomultiplier tube. The one gram sanple of polyethylene was too thick for the measurement of the beta-rays due to their lewer penetrability. Thus, for this measurement, a sanple 0.1 cm thick and 2 cm diameter was prepared after irradiation. Analysis of the beta spectrum permits the separation of the P-32 betas from other lewer energy betas. 

A radioactive isotope of phosphorus has a half-life of 14 days (that means it takes 14 days for the amount of to fall to half its original value, and another 14 days to fall to a quarter, and so on). We can plot a graph of amount of ip against time in days from these figures ... 

Seventeen radioactive isotopes of phosphorus are known also. A radioactive isotope is one that breaks apart and gives off some form of radiation. Radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive. 

One radioactive isotope, phosphorus-32, has applications in medicine, industry, and tracer studies. A tracer is a radioactive isotope whose presence in a system can easily be detected. The isotope is injected into the system where it gives off radiation. The radiation is followed by means of detectors placed around the system. 

CAS 7723-14-0. P. Nonmetallic element of atomic number 15, group VA of periodic table, aw 30.97376, valences of 1,3,4,5 allotropes white (or yellow), red, and black phosphorus. No stable isotopes, several artificial radioactive isotopes with mass numbers 29-34. 

Radioactive isotopes used in this way are called tracers . Apart from carbon, the radioactive isotopes of phosphorus and sulphur, and sometimes also the isotopes of nitrogen, oxygen, and hydrogen, are used in metabolic studies. 

The first radioactive isotope used in medicine was phosphorus-32, which was administered in 1936 to a woman who had chronic leukemia. The phosphorus-32 was artificially produced in a machine called a cyclotron, in which elements become radioactive after they are bombarded with neutrons and deuterium nuclei. 

The use of amplification reactions plays an important role in improving the sensitivity of some reactions, for example, the increase of phosphorus determination by the reduction of a heteropolycompound, ammonium phos-phomolybidate. Another way to increase the sensitivity of a reaction from a qualitative and quantitative point of view is the use of radioactive isotopes in chemical analysis. However, this area of analytical chemistry was replaced by new, more sensitive, safer, and less hazardous techniques for qualitative and quantitative analysis (total analytical techniques), such as inductively... 

Although the only naturally occurring isotope of phosphorus is P, sixteen radioactive isotopes are known. Of... 

Later we demonstrated (1S7) the elevated catalytic activity with respect to dehydration of isopropyl alcohol and cracking of cumene of the solid tricalcium phosphate containing /3-radiators—radioactive isotopes of calcium and phosphorus. 

Radioactive isotopes for tracer studies may be prepared artificially from nonradioactive elements by bombarding them with suitable nuclear particles produced in a cyclotron or a nuclear reactor. The discovery of this effect was made in 1934 by the French physicists Irene Joliot-Curie (1897-1956) and her husband Frederic Joliot-Curie (1900-1958). They were studying the effect of bombarding light elements such as aluminum with alpha (a) particles, which are beams of helium nuclei, fHe. They noticed that, after the bombardment had ceased, a new form of radiation continued to be emitted, and they concluded that a new isotope had been formed. In the case of the bombardment of ordinary aluminum, HAl, with a particles, the product is an isotopic form of phosphorus, ifP, the most abundant isotope of phosphorus being f P. The process is... 

A neutron, on, is produced as well as the radioactive isotope of phosphorus. By methods such as this a very large number of isotopes have been produced, and several of them have been extensively used in biological and medical research. 

The half-life, defined in the previous section and listed for each isotope in Table 6 1, is an important property when designing experiments using radioisotopes. Using an isotope with a short half-life (for example, with tj/2 = 15 hr) IS difficult because the radioactivity lost during the course of the experiment is significant. Quantitative measurements made before and after the experiment must be corrected for this loss of activity. Radioactive phosphorus, an isotope of significant value in biochemical research, has a relatively short half-life (14 days), so if quantitative measurements are made they must be corrected as descnbed in Equations 6.7 and 6 8 More information about the choice of a radioisotope in an experiment, the detec-... 

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