We measured the adsorption of aniline and four chlorinated analogues using the batch equilibration method to evaluate the direct and indirect determinations of the adsorbed solute concentration and binary relationships between adsorption constants and selected chemical properties of the adsorbates. Also we assessed the chemical stability of labile organic compounds during the adsorption process, by simultaneously using radioisotopic and liquid chromatographic methods of analysis for14C-aniline and14C-4-chloroaniline. No significant difference in adsorption coefficients and equivalent precision of estimates was found between analysis methods for these two chemicals. Adsorption coefficients derived from direct compound analysis of solution and adsorbed phases were comparable to those derived from solution phase analyses alone. These studies, in which the adsorbed phase was first desorbed and then analyzed, provided assurance that conventional batch equilibration studies, in which the quantity of the adsorbed chemical was derived by difference, were accurately assessing the degree for adsorption of aniline and chloroanilines. The adsorption of aniline and chlorinated analogues was predictable from chromatographic capacity factors and estimates of their octanol-water partition coefficients.