Introduction

Abstract
In the continuous manufacturing of pharmaceuticals, in-line monitoring and control are essential. Many pharmaceutical manufacturing processes require pH adjustment. Here, an in-line pH neutralization system with both coarse and fine adjustments was designed, and promising results were obtained. In nonbuffered conditions, the proposed two-pump system was able to control the fluctuations within approximately 2 pH units near the equivalence point, for both aqueous solutions and organic–H2O mixtures with strong acid.