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J Pharm Biomed Anal

Title:		Mass balance method for SI-traceable purity assignment of synthetic oxytocin
Author(s):		Wang S; Wu P; Li M; Huang T; Shi N; Feng L; Li H;
Address:		"Division of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, PR China. Division of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, PR China. Electronic address: mingutah@hotmail.com. Division of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100029, PR China. Electronic address: lihm@nim.ac.cn"
Journal Title:		J Pharm Biomed Anal
Year:		2022
Volume:		20210929
Issue:
Page Number:		114401 -
DOI:		10.1016/j.jpba.2021.114401
ISSN/ISBN:		1873-264X (Electronic) 0731-7085 (Linking)
Abstract:		"Oxytocin is not only a significant peptide drug for enhancing uterine contractions, but also an emerging biomarker and therapeutic target of mental disorders in clinical practice. There is a pressing need for the standardization of oxytocin assays because of its low pharmaceutical quality and large variations among measurement approaches. International System of Units (SI)-traceable analytical methods and well-characterized pure reference materials are urgently needed to set up standard reference measurement systems in laboratory medicine, ensuring the accuracy and comparability of test results. Herein, the purity assignment of a synthetic oxytocin containing a disulfide linkage was established based on a mass balance method, which had never been performed for a cross-linked peptide. An in-house validated liquid chromatography-high-resolution tandem mass spectrometry method was developed for the determination of structurally-related impurities in the study material. Twenty-one structurally-related impurities including deamidations, oxidations, and amino acid insertions, etc. ranging from 0.05 mg g(-1) to 15.65 mg g(-1) were identified and quantified by applying a hierarchy calibration concept. This study subsequently discusses a fit for purpose assessment for non-peptide related impurities including water, non-volatile counterions, inorganic elements, and volatile organic compounds that were determined using coulometric Karl Fischer titration, ion chromatography, inductively coupled plasma mass spectrometry, and headspace gas chromatography-mass spectrometry, respectively. The resulting assigned value (796.5 mg g(-1)) is determined to be traceable to SI associated with a small measurement uncertainty of 6.5 mg g(-1) (k = 2). The method developed in this study has been verified through an international key comparison jointly coordinated by the Bureau International des Poids et Mesures and the National Institute of Metrology"
Keywords:		"Amino Acids Chromatography, Liquid Humans *Oxytocin Reference Standards *Tandem Mass Spectrometry Disulfide bond Mass balance Oxytocin Purity assignment Synthetic peptide;"
Notes:		"MedlineWang, Sheng Wu, Peize Li, Ming Huang, Ting Shi, Naijie Feng, Liuxing Li, Hongmei eng England 2021/10/18 J Pharm Biomed Anal. 2022 Jan 5; 207:114401. doi: 10.1016/j.jpba.2021.114401. Epub 2021 Sep 29"