Chromatographic methods in radiation chemistry

Abstract

Recent developments in detectors for liquid chromatographic analysis have increased detection sensitivities by several orders of magnitude. Many products in the radiolysis of organic substrates can now be determined at micromolar levels. With this sensitivity it is possible to examine radiolytic systems in detail with doses as low as 100 rads. As a result one can determine initial yields in studies which here-to-fore have not been possible. This presentation describes studies of the oxidation of aromatic systems by HPLC methods involving spectrophotometric detection with diode array detectors. Digital storage of 3-dimensional data makes it possible to display readily the chromatographic data in a variety of formats. As a result one obtains an in depth understanding of the product distribution and considerable insight into the radiation chemical mechanism. These spectroscopic approaches can be supplemented by chromatographic studies employing electrochemical, refractive index, radiochemical and ion detectors which are particularly useful when reference samples of radiolytic products are not available. We illustrate these approaches with results from recent studies of the radiolytic oxidation of substituted naphthalenes and biphenyls where the complex mixtures of isomeric products can be resolved by HPLC methods. These studies provide information on the features which control the position of attack of OH on aromatic systems.