Poster Topical Area: Vitamins and Minerals
Location: Hall D
Poster Board Number: 472
Background: Epidemiological study on iodine requires tests for iodine content in huge amount of biological samples. Meanwhile iodine balance study on adults, infants, pregnant and lactating women is essential to provide strong evidence for Dietary Reference Intakes (DRIs). Thus iodine concentration in a large number of food, water, table salt, urine, breast milk and feces samples need to be analyzed. In addition demand for the assessment of iodine content in serum and saliva samples is increasing due to the rising awareness of iodine status. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) prevails in determining elements, including iodine, as its rapidity, low detection limits and minimal sample amount needed for analysis. Objective: To develop a fast, simple, and cheap method to determine iodine concentration in a large number of samples for iodine balance study and iodine status survey or evaluation.
Methods: (1) Food and feces: Weigh 0.2g homogenized samples and digest with 4.8mL 1% tetramethylammonium hydroxide (TMAH) in 5mL Eppendorf (EP) tubes at 90°C for 24h. Then transfer 0.5mL supernatant into 2mL EP tubes after centrifuge at 3000 rpm for 15min. Finally dilute with 1.5mL ultra-purified (UP) water and centrifuge at 12000 rpm for 5min. (2) Brest milk: Transfer 0.25mL samples into 5mL EP tubes along with 2.75mL 0.5% ammonia and digest at 90°C for 3h followed by centrifuge at 3000 rpm for 10min. After that, transfer 0.5mL supernatant into 2mL EP tubes followed by diluted with 1.0mL UP water. (3)Drinking water, serum, urine, and saliva: Directly diluted the samples with 7mmol/L ammonia at the ratio of 1:10, 1:30, 1:40, and 1:10 respectively. (4)Iodized salt: Dissolve 0.2g sample in 4mL UP water and then dilute 100 times with 7mmol/L ammonia. All the final solution can be injected into ICP-MS for iodine analyzing.
Results: The precision (RSD: 0.90%-3.32%, n=7) and recovery rate (86.80%-117.02%) of the method for determine above samples were satisfactory.
Conclusion: These sample treatments make iodine determination in a large number of samples fast, simple and cheap and it can be used for iodine status survey or evaluation, especially for iodine balance study.
Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University
Tianjin, Tianjin, China (People's Republic)