Radiotracer exchange techniques

Falkner and Edmond [334] determined gold at femtomolar quantities in seawater by flow injection inductively coupled plasma quadrupole mass spectrometry. The technique involves preconcentration by anion exchange of gold as a cyanide complex, [AulCNjj], using 195Au radiotracer (ti/2 = 183 days) to monitor recoveries. Samples are then introduced by flow injection into an inductively coupled plasma quadrupole mass spectrometer for analysis. The method has a detection limit of 10 fM for 4 litres of seawater preconcentrated to 1 ml, and a relative precision of 15% at the 100 fM level. 

Yeager and Steck derived diffusion coefficients for water in totally hydrated Nafion 120 membranes that were exchanged with alkali metal cations, using a radiotracer technique. At 25 °C, 77for the Na+ form was 2.65 X 10 cm /s and the values for the K+ and Cs+ forms were somewhat smaller, which would seem to reflect the lower maximal degree of hydration of these forms. 

The use of radiotracers is an excellent technique for measuring the solubility product constant of sparingly soluble salts or for making other studies of substances present in low concentrations. Another very important and classic example of the use of radiotracers is that of studying the occurrence and properties of isotopic exchange reactions—reactions of the type... 

Another example of the application of radiotracer techniques is the investigation of electron exchange reactions between atoms of the same element, for example... 

One of the most useful experimental methods to be applied to protein adsorption in recent years is the radiotracer technique (Mura-matsu, 1973). Proteins labeled with, 31I and 125I (Brash et al., 1974) and [14C]acetyl derivatives of proteins (Phillips et al., 1975) have been used as tracers. As well as measuring adsorption directly, this method has the great advantage that it can detect exchange between interface and bulk even when the total amount adsorbed does not vary. A technique that has been used to obtain independent measurements of the amount of protein adsorbed by measuring film thickness is ellipsometry (Trurnit, 1953). 

Chemicals Batch distillation still Leakage of steam from the reboiler contaminated overhead product with water. A radiotracer technique diagnosed the source of leak and measured the rate of leakage. Radiotracer techniques are useful for diagnosing exchanger leakage problems. 

The sensitivity inherent to the radiotracers techniques makes them extremely precious for the detection of leaks in pipes, heat exchangers, condensers and valves. The measures are realized while the units stay on operation and without interfering with the process. 

Isotopic exchange is the best example of the power of radiotracer techniques in chemical research. Isotopic exchange reactions have no inactive analogies. A system with two states of an element in equilibrium apart from isotopic distribution can be studied ... 

Using the radiotracer method, the strength of the ion-polymer interactions can also be studied, which is certainly a special advantage of this technique. When unlabeled species are added to the solution phase in great excess, the sorbed species are exchanged provided that there are no strong interactions (chemical bonds) between the ions or molecules and the polymer. 

The rate of the metal-ion exchan for the trivalent ions (Am, Cm, Bk, Cf and Eu) withEuEDTA" (ChoppinandWilUams 1973, Williams andChoppin 1974,D Oheslager et al. 1970) and (Ce, Eu and Am) with LaEDTA (D Olieslager and Choppin 1971) was studied using radiotracer techniques. The exchange was found to be a first-order reversible reaction and both the forward (kf) and the reverse (fc,) rate constants contained an acid-dependent and an acid-independent term,... 

The simultaneous diffusion of 210pb and l Cd into ion-exchange purified single crystals was studied by using the serial sectioning radiotracer technique. It was found that the diffusion data, for 347 to 569C, could be described by ... 

He developed an in situ radiotracer technique which is called thin-foil radio-tracer method [95, 96] (Fig. 12.31). It has been proved to be a very powerful tool for the investigation of electrosorption and electrocatalytic phenomena at solid electrodes, ionic exchange processes in polymer-modified electrodes, and electrochemical oscillations [97-99] (Figs. 12.32, 12.33, and 12.34). 

Ram KD, Tripathi R (1990) Study of iodide- iodate isotopic exchange reaction in a few eutectic melts by radiotracer technique. Appl Radiat Isot 41 879-885, extrapolated... 

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