Simple semi-automated procedure for determining the lipophilic nature of organic compounds

Abstract

This paper describes a semi-automated procedure for determination of the relative lipophilicities of organic compounds within a homologous series. The principle of the method is based on the ability of flexible polymer tubing to absorb highly lipophilic materials more readily than less lipophilic materials. The experimental assembly consists of a Technicon proportioning pump that generates two continuously flowing streams of an aqueous solution of the test compound and an ultraviolet spectrophotometer equipped with flow cell and recorder. The first stream passes through the flow cell without being pumped through polymer tubing, thus representing the reference sample. The second stream, however, is “tube-partitioned.” It arrives in the flow cell after the first stream and is recorded as a second peak shortly after the reference sample. The ratio of the peak heights was found to be a measure of the lipophilic nature of the compounds investigated. Substituted phenylureas and sulphonamides were screened by the new procedure and the results compared with those obtained by more conventional approaches using linear regression analysis.