Determination of iodine in milk powder by combing microwave digestion with inductively coupled plasma mass spectrometry

Abstract

Objective: This study aimed to establish an efficient and accurate method for the determination of total iodine in milk powder by microwave digestion combining with inductively coupled plasma mass spectrometry (ICP-MS). Methods: Firstly, 0.2 mL of precipitant and 5 mL of ultrapure water were added for mixing and standing, and then 5 mL of nitric acid was added for microwave digestion. After cooling, the volume was fixed to 35 mL with ultrapure water, and then 10 mL of ammonia, 1 mL of stabilizer and 50 μL of TritonX-100 were added in sequence, avoiding the iodine loss. Results: The detection limit was 0.044 mg/kg, while iodine presented favorable linearity in the range of 0~20 μg/L with correlation coefficient (r) of 0.999 9. The precision of the method (RSD %) was less than 5%, and the spiked recoveries of real samples is 90.2% ~ 107.7%. The measured values of various standard substances are consistent with the labeled values. The iodine content of the same milk powder was similar to that of GB 5009.267—2020. Conclusion: The method showed the advantages of high efficiency, good recovery and accurate for the determination of iodine contents in milk powder, ensures personnel safety and reduces instrument maintenance cost.

Keywords

• iodine
• milk powder
• microwave digestion
• inductively coupled plasma mass spectrometry (icp-ms)