Radiochemical Labeling

A more insight in the details of the reaction kinetics may be obtained by combined radioactive labeling and electrochemical measurements of adsorption/desorption of methanol at platinum and platinum-rathenium alloy nanoparticle fuel-cell catalysts. 

Experiments were conducted at room temperature in a three-electrode radio-electrochemical cell depicted in Fig. 1. The cell design enables electrolyte exchange under electrode potential control. An Ag/AgCl/ 3M NaCl electrode was used as a reference (E = 0.206 V vs. the standard hydrogen electrode, SHE), but all the po 

Both the foil and the metal film containing the catalyst are thin enough to allow p-radiation from the solution, and from the adsorbate to reach the detector at acceptable p-radiation attenuation. Therefore, the components of the total count rate are the count rate from the bulk solution and from the electrode 

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This reaction was also carried out with 14C-labeled formic acid, leading to the radiochemically labeled s,-triazolo[4,3-a][ 1,4]benzodiazepine (58% yield).[153]... 

The synthesis of 188Re [325] and "mTc [326] complexes as radiochemical labeling agents using microwave irradiation has been investigated by the group of Park. 

The use of a radioactive label (mainly 1251) not only attributed to the excellent sensitivity of RIA but also to the excellent flexibility and precision of radiochemical labeling and its high robustness with regard to interferences because of the hard signal. 

Proof that a lysine residue has been modified can be readily obtained because pyridoxyl derivatives of lysine possess characteristic white-blue fluorescence (Ronchi et al. 1969). In addition, they have a distinctive absorption maximum at 325 nm with of 9710 cm (Fisher et al. 1963). Finally, a radiochemical label can be introduced by reducing the pyridoxal-5-phosphate protein complex with tritium-labelled sodium borohydride. The peptide containing the derivatized lysine can therefore be detected either by fluorimetry, spectrophotometry or radiochemical techniques following routine procedures of proteolytic digestion and fractionation. Acid hydrolysis in 6 N HCl for 24 hr of peptides containing pyridoxal-5-phosphate lysine yields pyridoxyl-lysine since phosphate esters are readily hydrolyzed under these conditions. Pyridoxyl-lysine is eluted between lysine and histidine from a 55 cm column of Beckman 50 resin with 0.15 M citrate buffer pH 5.28. 

C-Labelled phosgene is a useful material in radiopharmaceutical and nuclear medical applications, since it combines the radiophysical properties of C with the extensive reaction chemistry of phosgene to permit the rapid synthesis of a wide range of biologically-active materials with radiochemical labels. Carbon-11 is a short-lived positron-emitting radionucleide, useful for in vivo measurements with positron emission tomography (PET) [519], Because of... 

A variety of analytical techniques [e.g., radiochemical labeling [3-7], UV-VIS [8,9], HNMR [8,9], and CNMR [10-15] have been used to determine the initiator residues incorporated into vinyl polymers during their preparation. In general, these techniques are not sufficiently sensitive to the environment of the initiator derived functionality to allow assignment of its mode of incorporation into the polymer. However, by using labeled initiators, NMR has been successfully utilized to analyze the nature of initiator derived residues and functionalities in polystyrene. 

Permeation Experiments. Encapsulated fluorescent and radiochemical labels are commonly used to evaluate permeabilities. Three different types of experiments allow to determine the permeation coefficient. 

Wunderlich, G. Dreyer, R. Fischer, S. Radiochemical labeling of protein particles with astatine. Ger. (East) DD 234870, 1986 Chem. Abstr. 1986, 105, 178470. 

As an additional approach in preparing a H-labeled anthraquinone, the radiochemical labeling of emodin (33) was undertaken (Groger et al., 1968). Reaction with 10 Ci tritium gas for 3 wk (Wilzbach conditions) (Wenzel and Schulze, 1962) yielded, after exchange of the labile tritium and intensive purification, crystalline emodin (33) with specific tritium radioactivity of 11.6 mCi/mmole. As usual with Wilzbach tritiations (Evans, 1974), the radioactivity was predominantly located on the aromatic nucleus, and the C-methyl radioactivity as determined by Kuhn-Roth oxidation amounted to only 8.5% of the overall radioactivity. 

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