Determination of iodine species in seaweed and seawater samples using ion-pair reversed phase high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry†
Ion-pair reversed phase high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (RP-HPLC-ICP-MS) has been used to determine two inorganic iodine species (I− and IO3−) and two organic iodinated amino acids (MIT and DIT) in seaweed and seawater samples within 5 min. The mobile phase used for a reversed phase C18 column was as follows: 2.0 mM tetraethylammonium hydroxide, 10 mM L-phenylalanine and 1% methanol (pH 8.9). Values of 1.5 mL min−1 for the flow rate of the mobile phase and 25 °C for the column temperature were selected for rapid separation of iodine species. The detection limits for IO3−, I−, MIT and DIT were 0.061, 0.052, 0.079 and 0.24 μg L−1, each, and the repeatabilities of peak height and peak area (20 μg L−1 for iodide and iodate, 40 μg L−1 for MIT, 100 μg L−1 for DIT) were all lower than 4%. Under the optimized conditions, the proposed method was successfully applied for the speciation analysis of iodine in seaweed and seawater samples. Recoveries of IO3−, I−, MIT and DIT in seaweed and seawater samples were between 90 and 110%. All results prove its advantages including high sensitivity, environmentally friendly, low time consumption, which are beneficial for routine analysis of iodine speciation in environmental and food fields.