Determination of Protein Content of Alhydrogel-absorbed Vaccine Using O-phthalaldehyde(OPA) Fluorometric Method

Objective:To develop a generic method for the determination of protein content in alhydrogel(aluminum) absorbed vaccine formulation using o-phthalaldehyde(OPA).Method: based on the theory that OPA can react with amino acids under alkaline conditions and give strong fluorescence,in the presence of 2-mercaptoethanol,a fluorescent method without antigen extraction was developed and the specificity,linearity range,accuracy and precision were evaluated.The integrity of the vaccine formulation was also investigated by SDS-PAGE.Results: a good linearity was obtained from 0.02mg/ml to 0.16mg/ml of antigen content,the accuracy of 90%~115% and CV% less than 15% were achieved.Little protein disassociation was also observed after CpG was added into the formulation.Conclusion: the OPA fluorescent method was simple and can be further used not only in the laboratory but also in routine quality control of the vaccine formulation with alhydrogel.