ABSTRACT
Radioactive isotopes are widely used as tracers or labels for substances separated by thinlayer chromatography for following the course of chemical and biochemical reactions and determining the qualitative and quantitative distribution of substances in a reaction mixture; for elucidating metabolic pathways of drugs (Inoue et al., 1997), pesticides (Tal and Rubin, 1993; Matsunaga et al., 1997), pollutants, and natural substances in human, animal, and plant tissues or soil; assessing the purity of isotopes (Gattavecchia et al., 1994; Mallol and Bonino, 1997); and for biochemical studies such as elucidation of biochemical pathways, radiotracer binding (Zamora et al., 1996), and assessment of enzyme activity. Because of the low detection limits and variety of methods for detecting and quantifying tagged compounds, thin-layer radiochromatography (TLRC) is often the only reasonable means of carrying out such studies. TLRC is advantageous compared to gas and column liquid chromatography with radiodetectors because all of the radioactivity can be accounted for on the layer (except for volatile components); therefore, recovery experiments to prove complete elution of radioactivity from the column are not required (Clark and Klein, 1996). Early general reviews of isotope techniques in TLC were given by Mangold (1969), Roberts (1978), Snyder (1969), and Prydz (1973). More recent information on procedures, instruments, and applications of radio-TLC were published by Shulman and Weaner (1991), Filthuth (1990), Rapkin (1990), Dallas et al. (1988), Touchstone (1992), and Clark and Klein (1996).
