Profile Analysis of Iodine in Powdered Infant Formula and Infant Complementary Foods by Inductively Coupled Plasma Mass Spectrometry

Abstract

Background: Both iodine deficiency and excessive iodine intake are very detrimental to the development of the baby, it is necessary to accurately measure the iodine content in infant milk powder. A probing study to establish a reliable and robust method for determining the iodine concentration using the inductively coupled plasma mass spectrometry was performed in combination with a sample digestion step. Methods:A sample was digested in 5% tetramethylammonium hydroxide at 85°C. This method adopted a shorter extraction time (3h) and used 186 Re as the internal standard, which exhibited greater stability in infant foods. The linearity range (R 2 ) was >0.998, limit of detection was 0.01 mg kg -1 , limit of quantification was 0.03 mg kg -1 , relative standard deviation was less than 4%, and recovery range was 94.8%-109%. Results:The accuracy of the optimized method was evaluated by testing standard reference material SRM 1849a, and the results (1.17 ± 0.05 mg kg -1 , n = 6) were in good agreement with the certified value (1.29 ± 0.11 mg kg -1 ). Conclusions:The results of the validation process confirmed that ICP-MS is the gold standard for determination of low iodine concentrations in infant foods. In addition, profiling the iodine content of different infant foods allows the development of a rational diet for infants to promote healthy development.