On-line version ISSN 1025-0298
IGLESIAS, Nuris et al. Preparation and Characterization of an Acetyl-Choline Working Reference Material for the Determination of O-Acetyl groups in Vaccine Polysaccharides. Vaccimonitor [online]. 2003, vol.12, n.1, pp. 18-22. ISSN 1025-0298.
The quality control of polysaccharides, used as vaccine antigens, requires the quantification of the O-acetyl group content. Together with other parameters, that determination provides criteria about the molecular integrity, which is very important for the immunogenicity, as in the case of Salmonella typhi Vi polysaccharide. The colorimetric method is the one most commonly performed. It requires an acetyl-choline chloride standard, for determining the standard curve used for the evaluation of test samples. The present paper describes the preparation and characterization of a lyophilized Acetyl-Choline Working Reference Standard (WRS), for use at the Finlay Institute laboratories involved in the quality control of purified polysaccharides from serogroup C Neisseria meningitidis and Salmonella typhi. The equivalent product from SIGMA was used as a reference for the characterization. The evaluated parameters were: linearity (r2 ≥ 0.99), in-lab precision (CV = 2.63%), reproducibility (CV = 2.73%), accuracy (96% recovery) and stability (from 10 months to the present). The results obtained during the characterization process of the WRS demonstrated that it is appropriate for use as a standard in the assay. That has been confirmed during more than 10-months use in the routine tests carried out in the laboratory.
Keywords : Acetyl-choline; O-acetyl group; polysaccharide; Salmonella typhi; Neisseria meningitidis; working reference standard.