Determination of Iodine in Dairy Products by ICP-MS

The samples were extracted by tetramethylammonium hydroxide and hydrogen peroxide. Using Te¹²⁸ as the internal standard, the iodine contents in dairy products were determined by inductively coupled plasma mass spectrometry（ICP-MS）. Detection limit of the method is 0.09 μg•L^-1, while the linear range is 0—400 μg•L^-1 and the linear coefficient(r) is better than 0.999 5. The precision of the method (RSD%) are all less than 5%. Precision and accuracy are evaluated by analysis of certified reference materials NIST 1549 non-fat milk powder. The determined iodine contents were in good agreement with the certified values. The recoveries of real samples are from 89.3%to 116.5%. The experiments show that this method is sensitive, simple and rapid， and accurate for the determination of iodine contents in dairy products.