The separation and determination of liothyronine and levothyroxine in tablets by reversed-phase high performance liquid chromatography.

A high performance liquid chromatographic (HPLC) system is described for the determination of liothyronine sodium (NaT3) and levothyroxine sodium (NaT4) in tablets using an octadecylsilane reversed-phase (RP-18) column packing with a mobile phase consisting of potassium dihydrogen phosphate, methanol, and water at 44 degrees C. After extracting the active ingredient from the excipients with dilute sodium hydroxide, an aliquot was chromatographed and the components were detected and quantitated by their UV spectrophotometric response at 254 nm.