Optimization of hydrolysis conditions of amino acid analysis for UHPLC-UV antigens content determination: Bexsero vaccine a case study

In the present study the compositional analysis of the amino acids released by the acidic hydrolysis of the vaccine antigens was approached as an alternative to the dye-binding methods, for improvement of the quality control. In particular, the Analytical Quality by Design principles were undertaken in optimizing the hydrolysis conditions of the antigens to be applied prior to the quantitation by UHPLC-UV. Bexsero was used as a case study; it is a recombinant meningococcal B vaccine and one of its critical quality attributes is the content of the three core protein antigens, namely Neisseria Heparin Binding Antigen, factor H binding protein and Neisseria adhesin A, in the final formulation. Conventionally, the proteins quantitation is carried out by dye-binding assays. Analytical Target Profile was defined as the accurate determination of amounts of the Bexsero antigens. The Critical Method Parameters were chosen by means of the cause-effect matrix. A Face Centered Design was used to select the experiments to investigate the process and finally a Method Operable Design Region with a risk of failure of 5% was defined. The selected working point for routine use was: hydrolysis time, 17 hrs; temperature, 112 °C; 6 M HCl volume, 300 µl; antioxidant 90% phenol volume, 5 µl.