Speciation analysis of urine iodine by ion-pair reversed-phase liquid chromatography and inductively coupled plasma mass spectrometry

Analytical Methods Pub Date: 2014-04-04 DOI: 10.1039/C4AY00396A

Abstract

This work described the utilization of ion-pair reversed phase liquid chromatography coupled to inductively coupled plasma mass spectrometry (RP-LC-ICP-MS) for iodine speciation analysis in urine. Considering the requirements of green analytical chemistry and the Ar ICP-MS instrument, three aqueous mobile phases were employed for the separation of seven iodine species including iodide, iodate and five iodo amino acids (monoiodotyrosine – MIT, di-iodotyrosine – DIT, tri-iodothyronine – T3, reversed tri-iodothyronine – rT3, and thyroxine – T4). The aqueous mobile phases were composed of an ion-pair reagent (tetrabutylammonium hydroxide – TBAH) and an eluent (ammonium chloride, L-phenylalanine or deoxycholic acid) at low concentrations in ultrapure water. Owing to tremendous difference in retention behavior between these iodinated forms, a gradient elution mode was performed for the rapid separation of IO3? and I?, MIT and DIT, and T3, rT3 and T4, respectively. Iodine species separation was achieved with a 12.5 mm C18 guard column in 7 min. The detection limits for IO3?, I?, MIT, DIT, T3, rT3 and T4 were 0.047, 0.046, 0.057, 0.072, 0.093, 0.094 and 0.081 μg L?1, respectively. Application of the proposed method was demonstrated by the speciation analysis of iodine in four real urine samples. The developed method offered satisfactory recoveries in the 93–106% range and good repeatability, showing great potential in routine analysis of iodine speciation in environmental, food and biological samples.

Graphical abstract: Speciation analysis of urine iodine by ion-pair reversed-phase liquid chromatography and inductively coupled plasma mass spectrometry
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