Effects of storage and cooking on the iodine content in iodized salt and study on monitoring iodine content in iodized salt.

In order to ensure that the intake of iodine from iodized salt is adequate, the effects of cooking, storage and iodination on iodine content in iodized salt have been studied. For monitoring the analytical performance, a quality control examination was also undertaken. The loss of iodine was greater when salt was stored in plastic bag than in glass bottle. The loss was greater in fortified salt stored at 37 degrees C and under 76% humidity than in that at 20-25 degrees C and under lower humidity. The retention of iodine varied with the kind of foods and also was influenced by the water content of cooked food. In general, the retention of iodine during cooking varied considerably (from 36.6% to 86.1%). The iodine concentration in salts varied greater from 3.0 to 100.3 mg/kg in salt for markets, and from 0 to 90.0 mg/kg in salts for households. 48.3% of samples from markets were found to be in compliance with national standards (30-50 mg/kg), and 72.0% of samples from households were in compliance with national standard (20-50 mg/kg). Analytical data collected from 8 of the cooperative laboratories for an analytical reference material showed a 95% confidence interval of the population mean for both precision and accuracy, falling within X +/- 2SD and passing quality control examination.