Studies on spin-trapped radicals in .gamma.-irradiated aqueous L-valine solutions by high-performance liquid chromatography and ESR spectroscopy

Electrophoretic analysis of quinone anion radicals in acetonitrile solutions using an on‐line radical generator

“…Electrophoretic methods can be useful tools to enable us to investigate such active analytes as a single component. Using spectrometers for flow systems, we will obtain many kinds of spectra (e.g., UV-visible, electron spin resonance (ESR) and NMR) of the targets as a single species, which are often difficult to be obtained using conventional methods [1,2]. Furthermore, the analytes as single species also can transfer to certain interaction fields, and we can investigate the interactions of them as shown in the present and the previous reports [3,4].…”

“…Such species can play important roles as intermediates of reaction, functional compounds and useful reagents in many fields of science. In studies of such species, detection and identification of the target is necessary and, if possible, separation of the species from coexisting substances to be a single component will be highly advantageous to a more exact and easy analysis of them [1,2]. Furthermore, stabilization of the species can occur by removal of quenchers coexisting in the generation matrices.…”

Non-aqueous Capillary Electrophoresis of p-Quinone Anion Radicals

“…Thus, in general, it will not be easy for radicals to survive during such separation procedures as HPLC, although there were earlier reports on the HPLC separation of spin-adducts for ESR spectroscopy analysis as exceptionally stable radicals. 19,20 A separation analysis of unstable radicals, however, is not impossible if we can remove the factors that quench and modify the radicals from the separation media. Separation, detection and determination of radicals as intermediates must give useful information to elucidate the mechanisms of interesting reactions.…”

Studies on γ-irradiated aqueous solutions of amino acids with functional groups by the spin-trap high-performance liquid chromatography – electron spin resonance method

“…By the separation of the spin adducts followed by their esr analysis, a number of free radicals from the amino acids and peptides (glycine (16), L-alanine (1 6), L-valine . (14), L-leucine (15), L-isoleucine (15), DL-methionine (1 3), L-proline (1 8), tr-ans-4-hydroxy-L-proline (1 8), glycylglycine ( l7), glycyl-L-alanine (1 7), L-alanylglycine (19), L-alanyl-L-alanine (19), and so on), many of which had not been found before this combination was used, could be detected and assigned. In addition, the spin adducts produced in the irradiated aqueous M N P solution have been separated and assigned to the structures so that the identification of the spin adducts from amino acids and peptides can be made more unambiguous (22).…”