Optical microscopy has long been used to characterise particulates present in biotherapeutic formulations, providing their size, shape and transparency characteristics. These can be used to group particulates into distinct classes such as aggregates, silicone oil and sundry contaminants.

However, the ability of a microscope to provide explicit identification is limited to the two-dimensional images it collects.

The addition of Raman spectroscopy to an automated microscopy system provides a robust primary identification method for the verification of particle chemistry and together the techniques offer the potential to enumerate, characterise and identify particulates in native formulations, as well as those immobilised on a filter substrate.