Protein molecules in solution can form proteinaceous particles by a variety of aggregation processes. The size and concentration of these particles is an important quality attribute for therapeutic MAb solutions. In this chapter, we describe the techniques commonly used to determine size and count of particles in solution for the size range 1 µm to 100 µm. After first discussing general principles of particle formation and properties, we present general guidance on sample handling and particle measurement, and then give detailed guidance on the application of the two most common techniques: light obscuration and flow imaging. The chapter concludes with a description of advanced techniques suitable for measurement of these particles.
State-of-the-Art and Emerging Technologies for Therapeutic Monoclonal Antibody Characterization Volume 2. Biopharmaceutical Characterization: The NISTmAb Case Study