High Performance Ion Pair Partition Chromatography: the Separation of Thyroid Hormones and Sulfa Drugs

Abstract

The combination of high performance liquid chromatography and high selectivity ion pair partition leads to the rapid separation of significant and difficult to resolve mixtures. In this paper we illustrate this method in the separation of thyroid hormones and metabolites and a group of related sulfa drugs. Selectivities in large measure can be understood in terms of differences in hydrophobic interactions of the substances with the aqueous phase. In the case of the sulfa drugs it is shown that a constant average butanol solvation number of 3.4 for the ion pair exists in the organic phase for butanol-hexane mixtures. The importance of this result to chromatography is noted. Finally, it is shown that static and chromatographic distribution ratios appear to be equivalent, even if high surface area porous supports are used.