Quantification of human urine and serum iodine by inductively coupled plasma mass spectrometry

Objective This paper aims at establishing a inductively coupled plasma mass spectrometry (ICP-MS) method for quantification and evaluation of iodine in human urine and serum in routine clinical laboratory. Methods This study was methodology validation research on iodine evaluation using ICP-MS. Ammonia, isopropanol and ultrapure water were mixed at certain ratio to dilute samples in the ratio of 1: 10, and then the diluted samples were analyzed by ICP-MS. Re was used as the internal standard. And linearity, lower limit of detection, recovery, precision, accuracy, carryover and stability was evaluated thoroughly. Results of iodine of pregnant women who required iodine tests were retrospectively analyzed to evaluate the status of iodine. Results The method only needs 30s for analysis of one sample. It was sensitive with a lower limit detection of 0.87 μg/L, the correlation coefficient was higher than 0.999 9 in ten measurements. The recovery in both serum and urine was approximately 100% (95.3% - 109.9%). Based on the NIST standard reference material 3668 comparison, the bias was less than 4%(-0.9% - 3.9%). The inter-coefficient variation (CV) for serum iodine and urine iodine was 1.2%-3.0%, 2.0%-2.9%, respectively; and total CV for serum iodine and urine iodine were 3.0%-3.8%, 4.1%-4.9%, respectively. The mean carryover of this method was 0.03% and iodine was stable for at least one month at -20℃ and 4℃. The urine and serum iodine for pregnant women was (154.8±89.7) μg/L (mean±SD), (75.8±21.4) μg/L, respectively. The correlation between urine and serum iodine was 0.21. Conclusion Establishe a rapid and simple ICP-MS method for urine and serum iodine measurement with high accurate and precise in routine clinical laboratory. (Chin J Lab Med, 2016, 39: 917-921) Key words: Mass spectrometry; Iodine; Orinalysis; Blood chemical analysis