[Characterization and uncertainty evaluation of aqueous reference materials for cholesterol]

Area of Science:

• Analytical Chemistry
• Materials Science

Background:

• Accurate quantification of cholesterol in aqueous solutions is crucial for clinical diagnostics and research.
• Development of reliable reference materials is essential for quality control and method validation.

Purpose of the Study:

• To characterize and evaluate the uncertainty of newly prepared certified reference materials (CRMs) for cholesterol in aqueous solution.
• To establish the homogeneity, stability, and measurement uncertainty of these CRMs.

Main Methods:

• Preparation of six candidate CRMs by dissolving certified reference material GBW09203b in methyl cyclodextrin aqueous solution.
• Assessment of homogeneity and stability using routine methods and isochronous stability studies.
• Evaluation of uncertainty components including purity, weighing, density, inhomogeneity, and instability, following ISO Guide standards.

Main Results:

• The six candidate CRMs demonstrated homogeneity and stability for at least one year at -70°C and -20°C.
• Relative uncertainties due to inhomogeneity ranged from 0.11% to 0.47%, and instability contributed 0.25% at -70°C.
• Measurement uncertainties were consistently low (0.05%-0.06%), significantly smaller than those from inhomogeneity and instability.

Conclusions:

• Six types of certified reference materials for cholesterol in aqueous solution were successfully prepared.
• These CRMs are characterized by homogeneity, stability, and reliability, suitable for analytical applications.
• The study highlights that inhomogeneity and instability are the dominant sources of uncertainty in these cholesterol CRMs.