FRI495 Analytical Validation Of An Inductively Coupled Plasma Mass Spectrometry Method For Measuring Iodine Content In Breast Milk

Disclosure: J. Li: None. L. Lee: None. F. Wang: None. C. Yang: None. C. Huang: None. Background: Adequate iodine status in lactating women is defined by a maternal median urinary iodine concentration above 100 μg/L. However, the current standard does not account for the secretion of iodine into breastmilk and could not truly reflect the amount of iodine delivered to the infants. Measuring breastmilk median iodine concentration (BMIC) is of crucial importance but the method to measure BMIC has not been developed and validated in Taiwan. Method: We adopted the ammonia dilution method without prior sample digestion to measure BMIC by inductively coupled plasma mass spectrometry (ICP-MS). Samples and iodine calibrators were prepared into an aqueous solution containing Triton X-100, 0.5% ammonia solution and tellurium ((128)Te) as the internal standard. Precision, accuracy, serial dilution, and recovery tests were performed for method validation. Results: The intra-assay and inter-assay coefficient of variation for the four human breast milk samples with different iodine concentrations ranged from 3.2% to 4.7% and 2.3% to 5.5%, respectively. The standard NIST 1549 milk powder was prepared into three different concentrations of 50 μg/L, 100 μg/L and 200 μg/L to assess accuracy and the biases were <5%. A recovery of 95-105% was achieved for four human breast milk samples spiked with sodium iodide solution. The serial dilution test confirmed linearity up to 500 μg/L. The limit for detection and quantification was 0.73 μg/L and 2.19 μg/L, respectively. Conclusion: The results of the current study confirmed that this ICP-MS method is accurate and reliable in measuring BMIC. Presentation: Friday, June 16, 2023