High-pressure liquid chromatography of amino acids, peptides and proteins. V. Separation of thyroidal iodo-amino acids by hydrophilic ion-paired reversed-phase high-performance liquid chromatography.

The separation of thyroidal iodoamino acids has been carried out by high-performance liquid chromatography in phase systems consisting of chemically bonded C18-hydrophobic supports as the stationary phase and water-organic solvent mixtures containing phosphoric acid or other ion-pairing reagents as the mobile phase. Under conditions of hydrophilic ion-pair formation, excellent resolution of the iodoamino acids is observed. This method permits the rapid separation and, hence, analysis of mixtures containing thyroxine, 3,3',5-triiodothyronine and 3,3',5'-triiodothyronine and related compounds in ca. 30 min with sensitivity, using a UV monitor at 210 nm, at the 1-10-pmole level.