Analysis of iodine species in aqueous solutions

Iodine is a biologically important trace element. Its behaviour in the environment and in human metabolism is determined by the type of iodine species which takes part in chemical reactions. Knowledge of their concentrations is necessary to understand and describe the iodine reaction paths. A separation procedure is proposed for quick determination of common forms of iodine—iodide, iodate ions, molecular iodine and organoiodine (in the form of CH3I). The procedure consists of sequential sorption by passing the sample solution first through a solid-phase extraction cartridge to separate I2 and CH3I from IO3 − and I− then through an anion-exchange resin in a cartridge to retain the latter two species. Each loaded cartridge is eluted to separate the sorbed pair of species. Concentration determination of the resulting four solutions can be performed by standard methods, e.g. by spectrophotometry, tracer counting or with ion-selective electrodes.