title: Validation of an optimized method for the determination of iodine in human breast milk by inductively coupled plasma mass spectrometry (ICPMS) after tetramethylammonium hydroxide extraction.
abstract: In this study a novel method to determine iodine concentrations in human breast milk was developed and validated. The iodine was analyzed by inductively coupled plasma mass spectrometry (ICPMS) following tetramethylammonium hydroxide (TMAH) extraction at 90°C in disposable polypropylene tubes. While similar approaches have been used previously, this method adopted a shorter extraction time (1h vs. 3h) and used antimony (Sb) as the internal standard, which exhibited greater stability in breast milk and milk powder matrices compared to tellurium (Te). Method validation included: defining iodine linearity up to 200μgL(-1); confirming recovery of iodine from NIST 1549 milk powder. A recovery of 94-98% was also achieved for the NIST 1549 milk powder and human breast milk samples spiked with sodium iodide and thyroxine (T4) solutions. The method quantitation limit (MQL) for human breast milk was 1.6μgL(-1). The intra-assay and inter-assay coefficient of variation for the breast milk samples and NIST powder were <1% and <3.5%, respectively. NIST 1549 milk powder, human breast milk samples and calibration standards spiked with the internal standard were all stable for at least 2.5 months after extraction. The results of the validation process confirmed that this newly developed method provides greater accuracy and precision in the assessment of iodine concentrations in human breast milk than previous methods and therefore offers a more reliable approach for assessing iodine concentrations in human breast milk.
authors.affiliation: FOODplus Research Centre, School of Agriculture Food and Wine, The University of Adelaide, Adelaide 5064, South Australia, Australia.
authors.forename: Dao
authors.initials: D
authors.lastname: Huynh
authors.affiliation: FOODplus Research Centre, School of Agriculture Food and Wine, The University of Adelaide, Adelaide 5064, South Australia, Australia; Women's and Children's Health Research Institute, Women's and Children's Hospital, King William Road, North Adelaide 5006, South Australia, Australia.
authors.forename: Shao Jia
authors.initials: SJ
authors.lastname: Zhou
authors.affiliation: FOODplus Research Centre, School of Agriculture Food and Wine, The University of Adelaide, Adelaide 5064, South Australia, Australia; Women's and Children's Health Research Institute, Women's and Children's Hospital, King William Road, North Adelaide 5006, South Australia, Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Gibson
authors.affiliation: Waite Analytical Service, School of Agriculture Food and Wine, The University of Adelaide, Adelaide 5064, South Australia, Australia.
authors.forename: Lyndon
authors.initials: L
authors.lastname: Palmer
authors.affiliation: FOODplus Research Centre, School of Agriculture Food and Wine, The University of Adelaide, Adelaide 5064, South Australia, Australia; Women's and Children's Health Research Institute, Women's and Children's Hospital, King William Road, North Adelaide 5006, South Australia, Australia; Sansom Institute for Health Research, University of South Australia, Adelaide 5001, South Australia, Australia. Electronic address: beverly.muhlhausler@adelaide.edu.au.
authors.forename: Beverly
authors.initials: B
authors.lastname: Muhlhausler
mesh_terms: D002138:Calibration; D005260:Female; D006801:Humans; D007454:Iodides / Q000032:analysis; D007455:Iodine / Q000032:analysis*; D057230:Limit of Detection; D008895:Milk, Human / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012015:Reference Standards; D015203:Reproducibility of Results; D013054:Spectrophotometry, Atomic / Q000295:instrumentation / Q000379:methods*; D013974:Thyroxine / Q000032:analysis
chemical_list: D007454:Iodides; D000644:Quaternary Ammonium Compounds; D007455:Iodine; C027917:tetramethylammonium; D013974:Thyroxine
keywords: Human breast milk; ICPMS; Iodine