Where do particle defects come from --- extrinsic, intrinsic or inherent?

Particle defects are classified by source into three categories: extrinsic, intrinsic, and inherent contamination.

Extrinsic particles are foreign to the product and process --- hair, cloth and paper fibres, environmental dust, and skin --- and signal a breakdown in gowning or environmental control. Intrinsic particles come from the process and product-contact materials --- glass from vials, rubber from stoppers, metal from equipment, and silicone --- and point to the container, closure, or line. Inherent particles arise from the formulation itself, such as protein aggregates or crystallization, and are a product characteristic rather than a contaminant. A related concept is Technically Unavoidable Particle Profiles (TUPPs), which define the baseline particle load a process cannot entirely eliminate. Knowing the source category is the first step in any contamination investigation because it directs the corrective action.

FTI builds challenge sets that represent each source category and supports root-cause investigations through particle characterization and plant-specific contact and non-contact material library kits, which let a facility match a found particle back to its exact source material.