When two laboratories measure the same biomarker, how can they know that their results are truly comparable? For angiotensin Ⅱ (Ang Ⅱ), this is an important practical question. Ang Ⅱ is a small peptide hormone that plays a central role in regulating blood pressure and fluid-electrolyte balance and is also used as a biomarker in laboratory testing related to vascular disease. For results obtained by different laboratories or analytical methods to be meaningfully compared, measurements need to be linked to reliable reference standards.
This need is particularly relevant because existing similar international Ang Ⅱ reference materials can be difficult to access and may face supply limitations. In a new study published in Biomedical Analysis, researchers developed and characterized a candidate reference material for Ang Ⅱ to provide an additional, well-characterized measurement benchmark. Reference materials function much like a common "ruler" for laboratory measurement: they allow laboratories to validate analytical methods, evaluate measurement performance, and compare results across different measurement systems.
To establish the new material, the researchers used two independent approaches—isotope dilution mass spectrometry and the mass balance method—to determine its purity. The methods rely on different measurement principles but produced closely consistent results, strengthening confidence in the assigned value. The material also showed excellent bottle-to-bottle homogeneity. The overall relative expanded uncertainty of the assigned value was 1.8% (k=2).
Importantly for practical use, the material remained stable for at least 12 months at −20 ℃ and for at least seven days at both 4 ℃ and 25 ℃ under simulated transportation conditions. The researchers also verified their measurements against NRC ANG Ⅱ-1, a certified reference material from the National Research Council Canada. The comparison met the accepted equivalence criterion, providing additional support for the accuracy of the assigned value.
The significance of the work extends beyond the characterization of a single reference material. By providing a common measurement benchmark, the material could support method validation, laboratory quality control, performance evaluation, and traceable measurement of Ang Ⅱ. In turn, this could help make Ang Ⅱ results obtained using different methods and in different laboratories more comparable.
The researchers caution that the study focused on the material's metrological properties rather than its biological activity. Its biological activity has not yet been examined, and further studies will be needed to determine whether it retains equivalent activity in vivo. Within this scope, the new reference material provides an additional tool for strengthening the standardization and traceability of Ang II testing.
DOI: 10.1016/j.bioana.2026.08.001
