Method developments for iodine speciation by reversed-phase liquid chromatography-ICP-mass spectrometry.

Method developments are described for a iodine speciation method. This method is based on a reversed-phase liquid chromatography separation combined with inductively coupled plasma-mass spectrometry detection. Investigations are performed concerning the methanol tolerance/stability of inductively coupled plasma, post-column oxidation/volatilization of iodine from species, influences of buffer pH, and column temperature on separation efficiency. The experiments focused on six iodine species, namely iodine, mono-iodothyrosine, di-iodothyrosine, tri-iodothyronine, reversed tri-iodothyronine, and thyroxin. Detection limits were determined between 0.08 and 1.5 µg/L (iodine related), dependent on species. Appplications on a urine sample were performed, showing iodide as the predominant iodine species.