Development of a certified reference material for Angiotensin Ⅱ with the mass balance method and isotope dilution mass spectrometry method

Angiotensin Ⅱ, the primary effector of the renin-angiotensin-aldosterone system, plays a significant role in blood pressure regulation and fluid-electrolyte homeostasis. It also serves as a crucial biomarker for vascular diseases. To ensure the metrological traceability and international equivalence of clinical Angiotensin Ⅱ testing, a candidate certified reference material was developed. The purity of Angiotensin Ⅱ was ascertained through two independent methods: isotope dilution mass spectrometry and mass balance. The isotope dilution mass spectrometry method yielded a mass fraction of 0.8732 g/g, whereas the mass balance method resulted in 0.8735 g/g. Statistical analysis verified the consistency between these methods, leading to a characterized value of 0.8734 g/g. The certified reference material exhibited excellent homogeneity and maintained stability under both long-term storage and simulated transport conditions, with a relative expanded uncertainty of 1.8% ( k = 2). Validation against the reference material NRC ANG Ⅱ-1 yielded an E n value of 0.112 (≤1), further validating the accuracy of the results. This reference material provides a robust metrological basis for the standardization of clinical assays associated with vascular diseases.