Quantification radioactive isotope

Precise quantifications are an important quality in molecular biology. There are slight differences in the methods used for global and targeted proteomics. In experiments intended to visualize as many proteins as possible, it is highly desirable to have a parallel quantification method that builds on the display technique. For 2D gel electrophoresis, fluorescent staining methods are under development (Urwin and Jackson, 1993), but they still lack overall sensitivity. Labeling proteins with radioactive isotopes is the most precise method for quantification but is limited to cell cultures, and alternatives are desirable. Recently, a precise method... 

Wolfe has presented an excellent description of the systematic application of stable and radioactive isotope tracers in determining the kinetics of substrate oxidation, carbon dioxide formation (including C02 breath tests), glucose oxidation, and fat oxidation in normal and diseased states. Quantification of the rate and extent of substrate oxidation can be achieved by using a specific or C-substrate which upon oxidation releases radioactive carbon dioxide. 

Measurement of the serum concentrations of administered antibodies is a general tool to evaluate their persistence in circulation. This is usually performed by introducing a sufficient amount of the test antibody either by the intravenous or by the intraperi-toneal routes (see Note 3), in a quantity that can be easily detected and quantified in serum samples, even after a two log reduction in concentration. The antibody tracer can be labeled with radioisotope which permits direct quantification in serum samples. To minimize radioactive isotope use, we use an antibody tracer that is unmodified or labeled with biotin or other derivation chemistries, and then determine its serum concentrations by ELISA techniques. We commonly inject 100 xg of the test antibody in a 200 xl volume of phosphate-buffered saline into each mouse intraperitoneally (i.p.) (see Note 4). This amount can vary depending on the goals of the experiment and the sensitivity of the detection method. A minimum of five inbred mice, sex-matched and age-matched, at 8-16 weeks of age are recommended for each antibody to be tested. 

Whether in the environment or in the human body, uranium will undergo radioactive decay to form a series of radioactive nuclides that end in a stable isotope of lead (see Chapter 3). Examples of these include radioactive isotopes of the elements thorium, radium, radon, polonium, and lead. Analytical methods with the required sensitivity and accuracy are also available for quantification of these elements in the environment where large sample are normally available (EPA 1980,1984), but not necessarily for the levels from the decay of uranium in the body. More sensitive analytical methods are needed for accurately measuring very low levels of these radionuclides. 

The experimental measurement of the cellular dose is very difficult. Some of the methods that have been applied to estimate the cellular dose are based on the measurement of intracellular uptake using analytical techniques, e.g., ICP-MS (for some metal NPs) and quantification of fluorescence or radioactivity (for NPs labelled with fluorescent probes of radioactive isotopes). These measurements are however very laborious and not possible to perform for all kinds of NMs. 

Quantification of functional sites on polymer surfaces. The principle of the method developed in our laboratory for these purposes is based upon the use of radioactive isotopes emitting soft- 3 radiation ( C, Ca). When a polymer film bearing functional sites capable of adsorbing S CN" or ions is placed in... 

Although traditional analytical techniques are essential for the quantification of drugs and all other compounds related to human life and the environment, the techniques involving radioactive isotopes have now become detenninanL Not only are they required by the health authorities in all countries, but there are many data that could not be obtained without them, as for example, whole-body auto-radiographic results and protein binding values. 

The quantification of gross root production, rhizodeposition, microbial assimilation, and the production of organic materials in soil has made increasing progress ever since stable ( C) and radioactive ( C) carbon isotopes have been used (see Chap. 12). Measurements of soil organic matter dynamics without these isotopes are difficult due to the large amount present as compared to the smaller rates of input. 

Low level radioactive waste Dissolution purification by coprecipitation, ion-exchange and electrodeposition a-Spectrometry (isotope quantification) 0.03 dpm No data Wessman 1984... 

Incorporated radioactivity, is measured by separation of isotope based on mass followed by quantification in gas ionization detector to measure isotope ratio. 

As mentioned in the Section 1, physico-chemical methodology for quantitative analysis of plant hormone focuses primarily on GC-SIM, although HPLC with selective fluorescence detection continues to be used for lAA analysis in some laboratories. Procedures, such as the 2-methylindolo-a-pyrone assay for lAA analysis [82], are now rarely utilised. With the exception of ethylene quantification [2] there is little use of non-MS-based GC detection techniques, despite the fact that selective analysis at the picogram level is achieved for ABA with an electron capture detector [83], and lAA and cytokinins with a nitrogen phosphorus detector [84,85]. The reason for the demise of these GC procedures is that the detectors are destructive and this precludes the reliable recovery of labelled internal standards for radioassay and isotopic dilution analysis. The usual compromise was to take two aliquots of the purified samples, one for GC analysis and the other for the determination of radioactivity. The accuracy of this approach is dependent upon the questionable assumption that the radioactivity in the purified sample is associated exclusively with the compound under study. In an attempt to circumvent this problem, a double standard isotope dilution procedure was devised for the quantitative analysis of lAA in which one internal standard was used to correct for losses during sample preparation and a second for GC quantification [86]. This procedure was used in several... 

Quantification of radioisotopes is done in terms of the energy emitted from the loss of an electron from the nucleus (i.e., isotopic decay), with the energy emitted being direetly proportional to the number of radioactive atoms (e.g., H,... 

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