To evaluate the uncertainty of the determination of polysaccharide content in Haemophilus influenzae type b (Hib) conjugate vaccine by ultraviolet-visible (UV) spectrophotometry.

According to the General Rule 3421 of the Chinese Pharmacopoeia, the polysaccharide content in Haemophilus influenzae type b conjugate vaccine was determined. Based on the experimental process, the Evaluation and Representation of Measurement Uncertainty, and the Guidelines for the Evaluation of Uncertainty in Chemical Analysis, the uncertainties of the measurement results were systematically evaluated.

The sources of uncertainty mainly included the preparation of standard solution u(P), sample processing u(S), standard curve fitting u(C), measurement repeatability u(rep), UV spectrophotometry u(I), and method bias u(B). The combined standard uncertainty (u_c) was 1.109 0 μg·mL^-1, and the expanded uncertainty (U) was 2.218 0 μg·mL^-1 (coverage factor k=2, 95% confidence probability). [HJ]

The dominant contributors to measurement uncertainty were standard curve fitting, sample processing, and method bias. The fitting of the control standard curve significantly reduces measurement uncertainty, with this effect being particularly pronounced. The uncertainty introduced during sample processing primarily stems from pipette operations, which necessitate rigorous metrological verification. While standard curve preparation is time-consuming, optimized workflow efficiency can be achieved by employing pipettes for sample processing volumes of 1 mL or greater and utilizing micropipettes for standard curve preparation when the volumes are 1 mL or less. Method bias-related uncertainty requires strict compliance with standardized testing protocols, with particular attention to meticulous control of experimental parameters. Furthermore, maintaining appropriate laboratory temperature conditions, implementing regular instrument calibration, and performing systematic equipment maintenance all contribute substantially to uncertainty mitigation. This study can provide references for uncertainty assessment of drug quality control based on UV spectrophotometry.