Development of a new tetrandrine certified reference material for clinical chemistry and pharmaceutical analysis
Certified reference materials (CRMs) with good metrological characteristics are essential tools to guarantee the reliability and validity of analytical measurements. However, in the research field of medical treatment and public health, compared with the number of marketed drugs or related medical products, the number of CRMs for clinical chemistry and pharmaceutical analysis is very limited. Based on this situation, a study towards a new tetrandrine CRM was carried out according to ISO guides 34 and 35. The study includes sample purification, homogeneity testing, stability study, characterization, and uncertainty evaluation. In the characterization of tetrandrine CRM, two methods based on different principles, namely, mass balance (MB) and differential scanning calorimetry (DSC) methods, were employed based on recommendations of the respective ISO Guides. The certified value of tetrandrine CRM is 99.7% with an expanded uncertainty of (+0.3%, −0.6%) (k = 2, P = 0.95). The tetrandrine CRM has been approved and assigned as a primary reference material and numbered as GBW 09544.