Separation of enantiomeric iodinated thyronines by liquid chromatography of diastereomers.

A method for the separation of D,L-triiodothyronine and D,L-tetraiodothyronine optical isomers is described. The iodinated thyronines are coupled with L-leucine and the resulting diastereomers are separated by reversed-phase liquid chromatography. The derivatives are detected in the UV region at 230 nm. The technique can be used for the determination of the optical purity of thyroid hormones. It is possible to determine 0.2% of the L-isomer in D-tetraiodothyronine with a relative standard deviation of 8%. One complete analysis takes about 2 h. The results are in good agreement with those of an enzymatic method.