Work with Radioisotopes

Frequently it is necessary to separate one isotope from other elements that may be present during its formation. The desired isotope is generally present in submicroscopie (tracer) quantities, together with other species that may be present either in large or small quantities. Precipitation methods, as widely used for ordinary chemical separations, may not 

Sometimes it is necessary to obtain an isotope from solution (or merely study its behavior), but stable nuclides of the element to be studied are nonexistent or unavailable. In such cases, an element having chemistry similar to that of the radioisotope may serve as a carrier. Thus, ReO has been used as a carrier for TcO, I as a carrier for At, and ThO2 as a carrier for Np02+. (If isolation of the new isotope is desired, there remains the problem, often difficult, of separation of the isotope from its carrier.) 

The use of carriers is less frequently necessary for separation methods other than precipitation (for example, liquid-liquid extraction, volatilization, electrolysis, and ion exchange). It must be remembered, however, that for work involving tracer quantities of a species in the absence of 

Assignment of an atomic number to a new radioactive nuclide is generally simpler than assignment of a mass number. The latter is sometimes accomplished by the method of cross bombardments, illustrated in Exercise 14. 

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There are, however, certain general principles of good practice which should constantly be kept in mind when working with radioisotopes. 

Laboratory coats may be worn if desired. It is a good idea to wear them when working with radioisotopes, since very small quantities of a radioactive solution can carry a significant amount of activity. It is also a good idea to wash your hands thoroughly with soap before leaving the laboratory to ensure that you do not take any chemicals out-... 

Use of radioisotopes in the laboratory generates potential biological hazards for investigators, and for all of society during subsequent radioisotope removal and disposal. Accordingly, those who work with radioisotopes should follow these safety precautions during all applications that employ radioisotopes. 

A variety of immunoassay techniques employ changes in the fluorescent properties of molecules to measure drug concentrations. Labelling of drugs with such molecules avoids the hazards of working with radioisotopes. Fluoroimmunoassays (FIA) also offer enhanced sensitivity in comparison to enzyme immunoassays they may be homogeneous or heterogeneous. 

The understanding of radioactivity has grown rapidly in the 100 years since its discovery. When the Curies worked with radioisotopes, they did not realize how harmful such materials could be. Marie Curie died of leukemia that was probably caused by her years of contact with radioisotopes. Many more radioactive isotopes exist than the few studied by the Curies. In fact, most of the roughly 2000 known isotopes of all elements are unstable and rmdergo nuclear decay. Fortrmately, most of those do not occur naturally, but are produced synthetically. Your surroundings contain mostly stable isotopes of the common elements, so you are not normally exposed to enough radiation to do you much harm. 

Because of the danger, elaborate and expensive precautions must be taken to protect people who work with radioisotopes. Highly radioactive waste products that can take many thousands of years to decay must be stored carefully. Choosing storage sites is difficult, and so is transport of the wastes to the storage sites. Many people are concerned about nuclear processes as energy sources. The threat of nuclear war and concern over radioactive fallout have also caused some people to be reluctant to use any form of radioactivity. 

Confine your work with radioisotopes to a small area in the laboratory. A convenient plan is to use a stainless steel tray lined with absorbent blotter paper coated on the bottom side with polyethylene. The paper must be replaced every day. If the radioactive matenals are volatile, the work should be done in a fume hood. If spills occur, a small work area such as a tray is much easier to clean than a large lab bench. If or other strong j8 emitter is used, it is necessary to work at all times with shielding between yourself and the radioactive samples. The most cost-effective and convenient shielding material is Plexiglas. The thicknesses of shielding required for various materials are given in Table 6.3. 

In order to work with radioisotopes, staff must be given training in the safe use of radioisotopes. In addition, in the United Kingdom, additional training is required for those responsible for the day-to-day maintenance and inspection of radioisotope facilities (the Radiation Protection Supervisor). Any establishment involved in work with... 

In a few institutions, however, waste water from chemical laboratories is collected and treated in campus facilities and recycled for irrigation. Where national regulatory authority exists for working with radioisotopes, government agencies typically collect and dispose of radioactive waste from laboratories. Most developing countries do not have similar arrangements for disposal of other hazardous chemicals. 

Working with Radioisotopes and Other Sources of Ionizing Radiation RAMP... 

Similarly, scientists working with radioisotopes (which is common in chemistry and biology labs where tracers are used) should work in chemical hoods designed for radioisotope work and allow for relatively easy decontamination. These hoods are fitted with HEPA and charcoal filters at the hood-exhaust... 

FIGURE 16.1 A person working with radioisotopes wears protective clothing and gloves and stands behind a shield. 

Safety guidelines and practices for working with radioisotopes can be classified in six different categories ... 

Each of these subjects is covered in detail in the next several pages. All laboratory workers who work with radioisotopes should know and observe all the pertinent rules in order to preserve the health and safety of the occupants of the laboratory and even of the building. In addition, strict observance of these rules will... 

Wash hands thoroughly and monitor hands upon removal of gloves both after completion of work with radioisotopes and also before leaving the laboratory. Pay particular attention to the nails, between the fingers, and around the outer edges of the hands. 

Avoid the use of containers, glassware, or equipment having sharp edges when working with radioisotopes. 

Label all storage cabinets, refrigerators, fume hoods, glove boxes, or other areas used for storage or work with radioisotopes with the appropriate caution sign(s). 

Do not permit untrained individuals to work with radioisotopes. All radiation workers must receive training in basic radiation safety principles and in handling techniques appropriate for the isotopes they will be using. 

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