Trace level determination of iodide, iodine and iodate by gas chromatography-mass spectrometry

A technique is proposed for the determination of iodine, iodide and iodate in aqueous solution. The sample preparation consists of the derivatization of iodine in the presence of 2,6-dimethylphenol and a single-step extraction of the derivative with diethyl ether. Iodine can be quantitatively converted into 4-iodo-2,6-dimethylphenol, which is then measured by gas chromatography-mass spectrometry with selected-ion monitoring. Iodide, is oxidized by 2-iodosobenzoate to iodine, and iodate is reduced with ascorbic acid to iodide. Limits of detection and the sensitivity of the procedure are discussed. The procedure is applicable to the quantification of the compounds in drinking water.