Determination of Iodine in Organic Compounds by Ion-Pair Chromatography with C30 as a Stationary Phase

A method for the determination of iodine in organic compounds has been developed for ion-pair chromatography (IP-HPLC) with a new C30 column, coupled with a UV detector at 230 nm. A phosphate buffer (pH 6.0) containing 2 mM tetrabutylammonium (TBA-HSO4) in 15(v/v)% acetonitrile was used as an optimal mobile phase for iodide ion. Especially the calibration curve was linear with excellent correlation coefficients of more than 0.9995; further, the relative standard deviations at 20 and 2 μg/ml were less than 0.27 and 0.45% based on 10 repeated measurements. This method was applied to the determination of iodine in organic compounds with an oxygen-flask-combustion method. Several mg of a sample was burned in an oxygen flask filled with 20 ml of 2 mM NaHCO3 and 100 ppm NH2NH2 as an absorbent; water was added to make 50 ml. A 20 μg liquid sample solution was injected into a column. The content of iodine by this method was in good agreement with that calculated based on the molecular weight.