Advanced raman spectroscopy in FDA forensic chemistry
Raman spectroscopy has become an indispensable analytical tool in the U.S. Food and Drug Administration’s (FDA’s) Forensic Chemistry Centre (FCC), where chemists such as Dr Mark Witkowski apply vibrational spectroscopy to identify adulterated, counterfeit, or contaminated pharmaceuticals, dietary supplements, and food products. As part of the Trace Examination Section, Witkowski’s work focuses on rapid, molecular-level characterisation of unknown substances submitted from criminal investigations conducted by the FDA’s Office of Criminal Investigations (OCI). His analyses play a central role in protecting consumers from fraudulent or hazardous materials circulating through domestic and international supply chains.
Counterfeit pharmaceuticals are a large proportion of the laboratory’s workload. High-value drugs, including PDE5 inhibitors, statins and clinically essential agents, are often replicated due to their economic value. Illicit manufacturers may substitute subtherapeutic or incorrect APIs, use atypical excipients, or even incorporate industrial fillers undetectable by visual inspection. Dietary supplements marketed for weight loss or sexual enhancement often contain undeclared APIs rather than botanical constituents.
Witkowski notes that some high-cost items, such as infant formula, have been fraudulently repackaged and replaced with lower-value substances; this has also been observed for over-the-counter pharmaceuticals. These incidents need accurate, non-destructive analytical workflows capable of detecting small-scale compositional deviations.
The Trace Examination Section specialises in the characterisation of unknown materials in pharmaceuticals, injectables, supplements, and adulterated food products. Because samples may serve as legal evidence, non-destructive methods and microscale chemical identification are essential. Raman spectroscopy is particularly suited to this task due to its ability to generate molecular vibrational fingerprints from intact solids, liquids, and microscopic particles without altering sample integrity.
Witkowski’s team employs Horiba‘s LabRAM IR2, a hybrid Raman/IR microspectroscopy platform that provides complementary vibrational information. Raman spectroscopy is sensitive to symmetric vibrational modes of nonpolar functional groups, while infrared spectroscopy enhances detection of polar groups and heteroatom-containing structures. The paired modalities enable analysts to reconstruct entire tablet formulations, identify excipient differences between suspect and authentic products, and find noncomforming materials indicative of illicit manufacturing.
For heterogeneous samples containing numerous discrete particulates, such as powders, injectables, and packaging residues, the lab uses a Horiba XploRA Plus equipped with the ParticleFinder automation module. This system automates the traditionally labour-intensive process of Raman particle-by-particle examination. ParticleFinder rapidly surveys large fields of view, isolates particles based on morphological criteria, and acquires Raman spectra selectively from those features. This significantly increases throughput and enables quantitative analyses of particle distributions that would be impractical with manual Raman microscopy.
Raman’s spatial resolution is particularly advantageous for analysing microscopic particulates, trace residues, and heterogeneous counterfeit matrices. When suspect tablets contain multiple unknown fillers, Raman microanalysis can isolate and identify individual components on the order of a few microns, capabilities not feasible with bulk analytical methods. This is critical when reconstructing counterfeit formulations or verifying whether a sample matches the compositional “fingerprint” of a legitimate manufacturer.
Following spectral acquisition and chemometric interpretation, the Trace Examination Section compiles detailed forensic reports that document material identity, ingredient composition, and deviations from authenticated reference products. These technical findings are integrated with supply-chain documentation and investigative evidence gathered by OCI. The analytical work performed by Witkowski and his colleagues frequently contributes to regulatory enforcement actions and federal criminal cases.
By applying advanced Raman spectroscopy and automated microanalytical tools, the FDA’s Forensic Chemistry Centre provides high-confidence molecular evidence essential to protecting the integrity of the nation’s food and drug supply. The combination of non-destructive analysis, microscale resolution, and dual Raman/IR capability positions these techniques as central components of modern forensic chemistry and regulatory science.
Contributed by Horiba
