A modified method for the determination of aluminium-gel in vaccine.

Abstract

The conventional method of aluminium analysis, described in the Biological Preparation Standard for Animals, was found to give erroneous results in the case of vaccine containing aluminium-gel as an adjuvant. This is because of incomplete decomposition of the gel and unsettled reaction system for the determination. But these problems were settled definitely. Heating on a direct fire for 15 min, by which temperature of the content attained 115-120 degrees C at atmospheric pressure, allowed the gel to complete decomposition and the result came to close the theoretical value. And a constant result by the decomposition itself was obtained with 2 volumes of nitric acid against 1 volume indicated in the standard method. Quantitative reaction of the gel-decomposed solution did hold in range of about 0.75-2.0 micrograms aluminium per ml. Use of acetate buffer solution for dilution of the decomposed solution following by sampling in 2 volumes of the dilution into the reaction mixture made the variation to the least as compared with the water-dilution following by 1 volume sampling indicated in the standard method. By these modified conditions, we succeeded in reducing the relative error and the coefficient of variation to less than +/- 5% and +/- 2% respectively.