Development of Certified Reference Material of L-Thyroxine by Using Mass Balance and Quantitative Nuclear Magnetic Resonance

L-thyroxine (T4) is an important hormone for diagnosing and evaluating thyroid function disorders. As outlined in ISO17511, having a certified reference material (CRM) is crucial for ensuring that the results of clinical tests are traceable to the SI-unit. This study employed two principal methods t...

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Main Authors: Qiang Zhao, Weifei Zhang, Dan Song, Xirui Zhou, Xianjiang Li, Huan Yao, Wenjing Xing, Hongmei Li, Jian Ma, Peng Xiao
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/13/2840
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author Qiang Zhao
Weifei Zhang
Dan Song
Xirui Zhou
Xianjiang Li
Huan Yao
Wenjing Xing
Hongmei Li
Jian Ma
Peng Xiao
author_facet Qiang Zhao
Weifei Zhang
Dan Song
Xirui Zhou
Xianjiang Li
Huan Yao
Wenjing Xing
Hongmei Li
Jian Ma
Peng Xiao
author_sort Qiang Zhao
collection DOAJ
description L-thyroxine (T4) is an important hormone for diagnosing and evaluating thyroid function disorders. As outlined in ISO17511, having a certified reference material (CRM) is crucial for ensuring that the results of clinical tests are traceable to the SI-unit. This study employed two principal methods to evaluate the purity of T4, mass balance (MB) and quantitative nuclear magnetic resonance (qNMR), both of which are SI-traceable (International System of Units) approaches. The MB method involved a detailed analysis of impurities, including water, structurally related compounds, and volatile and non-volatile substances. A variety of techniques were employed to characterize T4 and its impurities, including liquid-phase tandem high-resolution mass spectrometry, ultraviolet spectrophotometry, infrared spectroscopy, and both <sup>1</sup>H-NMR and <sup>13</sup>C-NMR. Additionally, impurities were quantified using Karl Fischer coulometric titration, ion chromatography, gas chromatography–mass spectrometry, and inductively coupled plasma–mass spectrometry. In qNMR, ethylparaben was used as the internal standard for direct value assignment. The results showed T4 purities of 94.92% and 94.88% for the MB and qNMR methods, respectively. The water content was determined to be 3.563% (n = 6), representing the highest impurity content. Ten structurally related organic impurities were successfully separated, and five of them were quantified. Ultimately, a purity of 94.90% was assigned to T4 CRM, with an expanded uncertainty of 0.34% (<i>k</i> = 2).
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spelling doaj-art-47c3aef7b14c476683c0f28f2d10b4b62025-08-20T03:28:33ZengMDPI AGMolecules1420-30492025-07-013013284010.3390/molecules30132840Development of Certified Reference Material of L-Thyroxine by Using Mass Balance and Quantitative Nuclear Magnetic ResonanceQiang Zhao0Weifei Zhang1Dan Song2Xirui Zhou3Xianjiang Li4Huan Yao5Wenjing Xing6Hongmei Li7Jian Ma8Peng Xiao9Department of Immunology, Second Affiliated Hospital of Harbin Medical University, Harbin 150081, ChinaDivision of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, ChinaDivision of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, ChinaDivision of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, ChinaDivision of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, ChinaDivision of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, ChinaDepartment of Immunology, Second Affiliated Hospital of Harbin Medical University, Harbin 150081, ChinaDivision of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, ChinaDepartment of Immunology, Second Affiliated Hospital of Harbin Medical University, Harbin 150081, ChinaDivision of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, ChinaL-thyroxine (T4) is an important hormone for diagnosing and evaluating thyroid function disorders. As outlined in ISO17511, having a certified reference material (CRM) is crucial for ensuring that the results of clinical tests are traceable to the SI-unit. This study employed two principal methods to evaluate the purity of T4, mass balance (MB) and quantitative nuclear magnetic resonance (qNMR), both of which are SI-traceable (International System of Units) approaches. The MB method involved a detailed analysis of impurities, including water, structurally related compounds, and volatile and non-volatile substances. A variety of techniques were employed to characterize T4 and its impurities, including liquid-phase tandem high-resolution mass spectrometry, ultraviolet spectrophotometry, infrared spectroscopy, and both <sup>1</sup>H-NMR and <sup>13</sup>C-NMR. Additionally, impurities were quantified using Karl Fischer coulometric titration, ion chromatography, gas chromatography–mass spectrometry, and inductively coupled plasma–mass spectrometry. In qNMR, ethylparaben was used as the internal standard for direct value assignment. The results showed T4 purities of 94.92% and 94.88% for the MB and qNMR methods, respectively. The water content was determined to be 3.563% (n = 6), representing the highest impurity content. Ten structurally related organic impurities were successfully separated, and five of them were quantified. Ultimately, a purity of 94.90% was assigned to T4 CRM, with an expanded uncertainty of 0.34% (<i>k</i> = 2).https://www.mdpi.com/1420-3049/30/13/2840L-thyroxinecertified reference materialmass balancequantitative nuclear magnetic resonance spectroscopytraceability
spellingShingle Qiang Zhao
Weifei Zhang
Dan Song
Xirui Zhou
Xianjiang Li
Huan Yao
Wenjing Xing
Hongmei Li
Jian Ma
Peng Xiao
Development of Certified Reference Material of L-Thyroxine by Using Mass Balance and Quantitative Nuclear Magnetic Resonance
Molecules
L-thyroxine
certified reference material
mass balance
quantitative nuclear magnetic resonance spectroscopy
traceability
title Development of Certified Reference Material of L-Thyroxine by Using Mass Balance and Quantitative Nuclear Magnetic Resonance
title_full Development of Certified Reference Material of L-Thyroxine by Using Mass Balance and Quantitative Nuclear Magnetic Resonance
title_fullStr Development of Certified Reference Material of L-Thyroxine by Using Mass Balance and Quantitative Nuclear Magnetic Resonance
title_full_unstemmed Development of Certified Reference Material of L-Thyroxine by Using Mass Balance and Quantitative Nuclear Magnetic Resonance
title_short Development of Certified Reference Material of L-Thyroxine by Using Mass Balance and Quantitative Nuclear Magnetic Resonance
title_sort development of certified reference material of l thyroxine by using mass balance and quantitative nuclear magnetic resonance
topic L-thyroxine
certified reference material
mass balance
quantitative nuclear magnetic resonance spectroscopy
traceability
url https://www.mdpi.com/1420-3049/30/13/2840
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