An unexpected particle found in a pharmaceutical product can compromise the product quality and threaten patient safety.
Identifying unexpected foreign particles in pharmaceutical products is essential for conducting thorough quality deviation investigations and executing effective root-cause analyses. Relying on visual appearance alone is insufficient; accurate chemical and physical characterization is required to pinpoint contamination sources, protect product quality, and satisfy regulatory mandates. Recent FDA recalls and warning letters underscore this necessity, citing diverse particulate materials such as cellulose, fiberglass, stainless steel, and rubber container-closure fragments etc.
What can foreign particle investigation tell us?
Foreign particles can have different compositions and origins. They may be associated with raw materials, manufacturing equipment, packaging components, the production environment or other sources. In some cases, particles may also originate from the product itself or form through interactions between formulation components and packaging materials.
Their appearance alone rarely provides a definitive answer. A particle that looks like a fiber, a metallic fragment, or a small piece of glass, still needs to be characterized before its identity can be established reliably. In past 2025 and 2026, the FDA has issued more and more warning letters and 483 observation forms related to non-complete foreign matter investigation in production, demonstrating that this topic has also become critical for authorities. Understanding their composition can help teams assess potential contamination sources, investigate deviations and determine what additional evidence may be needed.
This distinction matters because the material’s identity can help narrow down potential sources and guide further investigation.
- Product vs. Environment: Distinguishes whether the particle originated from raw materials, equipment wear, packaging elements, environmental exposure, or formulation-packaging interactions.
- Targeted Inquiries: Identifying a polymer prompts a different investigation path than discovering a metallic fragment or mineral contaminant.
For example, identifying a polymeric particle may prompt a different line of investigation than finding a metallic fragment or an inorganic particle.
Why is foreign particle identification challenging?
The analysis is not always straightforward. Particles can be very small, present in limited quantities or difficult to isolate from the surrounding product matrix. Their composition may also be complex, and different materials can have similar visual characteristics.
No single analytical technique necessarily answers every question. Microscopy can provide information about a particle’s morphology, but visual examination alone may not establish its chemical composition. Spectroscopic techniques can provide molecular information, while elemental analysis can help characterize inorganic materials.
The choice of analytical approach depends on the particle and the question being investigated. Combining complementary techniques can provide a more complete characterization than relying on a single observation or measurement.
Sample handling also matters. When only a small amount of material is available, the analytical strategy needs to make effective use of the sample while preserving the information required for subsequent investigations.
Which analytical techniques can identify foreign particles?
A combination of microscopy, spectroscopy and elemental analysis can help characterize foreign particles in pharmaceutical products. Each technique provides different information.
Optical and polarized light microscopy
Microscopy is often an important starting point. It allows analysts to examine a particle’s size, shape, color and other morphological characteristics. Polarized light microscopy (PLM) can provide additional information about optical properties, helping characterize the material and guide the next analytical steps.
Raman microscopy
Raman spectroscopy provides molecular fingerprint information that can help identify a material by its characteristic vibrational signals. When applied microscopically, it can be useful for analyzing individual particles and identifying many organic and certain inorganic materials, depending on their properties and the measurement conditions. Any suspicious reference/source material can also be analyzed by Raman to establish customized reference database for investigation.
Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX)
SEM provides high-resolution images of a particle’s surface and morphology. When combined with energy-dispersive X-ray spectroscopy, it also provides information about elemental composition. This can help characterize inorganic particles and investigate materials such as metals, glass and mineral contaminants.
These methods are complementary rather than interchangeable. A microscopy image, molecular spectrum and elemental profile each contribute different evidence. Their combined interpretation can help establish what a particle is and whether its characteristics are consistent with a suspected material or source.
How does particle identification support root-cause investigations?
Identifying a particle is an important step, but it does not automatically establish how or when the particle entered a product. That conclusion may require additional evidence, including information about manufacturing processes, equipment, raw materials and packaging components.
Analytical characterization can nevertheless help make an investigation more focused.
For example, when an unexpected particle is found during routine quality control, its composition may help determine which potential sources deserve further examination. When a deviation or out-of-specification (OOS) result requires investigation, particle identification can provide additional evidence to support the assessment.
Supplier changes can also prompt further investigation when unexpected findings are found. When a pharmaceutical company changes its API, excipient or other raw material supplier, differences in material properties may require additional characterization. If an unexplained particle is detected, its composition and possible origin may need to be investigated to determine whether it could be related to the new material, its handling or another part of the manufacturing process. Comparing the particle’s characteristics with those of potential source materials may help assess whether the supplier change is relevant to the issue.
Similarly, if packaging or manufacturing equipment is suspected, comparing the particle’s characteristics with those of candidate materials may help evaluate possible explanations.
This information can support root-cause investigations, deviation assessments and the definition of appropriate corrective and preventive actions (CAPAs). The value lies in replacing assumptions based on appearance with analytical evidence that can be evaluated alongside other investigation findings.
Foreign particle identification may therefore be relevant even when the initial observation seems limited or isolated. The need for specialist analysis often becomes apparent only after the particle has been detected and its identity remains uncertain.
When should pharmaceutical companies consider specialist particle analysis?
Specialist foreign particle identification is always required and necessary when:
- An unexpected visible or subvisible particle is detected in a pharmaceutical product.
- Initial examination does not establish the particle’s identity.
- A deviation, OOS result or suspected contamination event requires further investigation.
- A supplier change is followed by an unexpected finding that requires investigation, particularly when a particle has been detected.
- A potential source involving raw materials, equipment, packaging or the production environment needs to be assessed.
- Additional chemical or elemental characterization is required to support a quality investigation.
These situations can appear across a wide range of pharmaceutical products and materials. Having access to specialized analytical techniques and experienced scientists can be particularly valuable when particles are difficult to isolate, their composition is unclear or the available sample is limited.
Foreign particle identification at Kymos Denmark
At Kymos Group’s Danish site, our team brings more than 20 years of experience in particle analysis, working with a broad range of pharmaceutical samples and materials.
Our GMP-compliant foreign particle identification service eliminates guesswork by delivering a comprehensive “morphological, chemical, and elemental” characterization workflow. We isolate and analyze trace contaminants to protect your product quality, defend your OOS investigations, and secure patient safety.
Every sample presents a unique challenge. Our technical specialists do not use a one-size-fits-all approach; instead, they carefully select the most appropriate orthogonal testing sequence based on your specific sample matrix and investigation goals. This deep regulatory and analytical expertise supports pharmaceutical companies across the entire product lifecycle for:
- Unexpected Particle Investigations: Rapidly dissecting sudden contamination events or anomalous particles discovered on the production floor or during packaging.
- Contamination Source Mapping & Root-Cause Analysis: Replacing visual assumptions with empirical data to trace contaminants back to mechanical wear, raw materials, or environmental sources, empowering your team to close Out-of-Specification (OOS) deviations and build effective CAPA plans.
Looking for specialized particle analysis support?
Whether you need ongoing analytical support or help characterizing an unexpected particle, our team can discuss your requirements and identify an appropriate analytical approach.
Learn more about Kymos Group’s Foreign Particle Identification service.
