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Identification of a mixed microparticle by combined microspectroscopic techniques: a real forensic case study in the
Xiaolin Cao1, Peter Masatani, Gianpiero Torraca
1Department of Formulation & Analytical Resources, Amgen Inc., Thousand Oaks, California 91320, USA. xiaolinc@amgen.com
Abstract:
Identification of foreign microparticles in drug products is one of the first steps in evaluating the nature of particle contamination and its consequences for product quality. To characterize various foreign particles, we use spectral database search methods as well as a number of microscopic and microspectroscopic techniques. Here, we report a case study involving the identification and root-cause investigation of a microparticle consisting of four compounds. Foreign microparticles consisting of mixtures pose unique challenges for identification as their spectra are difficult to interpret and general database searches usually return unsatisfactory results. Moreover, sample separation through purification and other manipulations is time consuming and often difficult for these microparticles due to their small sizes and the limited quantities of the components. Here we demonstrate an applicable methodology that combines multiple microscopic and microspectroscopic techniques to identify a heterogeneous microparticle without the need for sample purification or chemical separation. This methodology primarily combines Raman, infrared, and energy dispersive X-ray microspectroscopic techniques to obtain complementary spectral information for the identification of heterogeneous particles. With this methodology, the mixed microparticle investigated in this study was determined to consist of polyisobutylene, hydrated magnesium silicate, titanium dioxide, and silica, likely originating from the vial stopper material.
Insights
Foreign microparticle analysis in drug products is crucial for quality control. A new method identifies mixed-compound particles using combined Raman, infrared, and X-ray microspectroscopy without sample purification.
Area of Science:
- Pharmaceutical Science
- Analytical Chemistry
- Materials Science
Background:
- Foreign microparticle identification is critical for drug product quality assessment.
- Characterizing mixed-compound microparticles presents significant analytical challenges due to complex spectra and difficulties in sample preparation.
- Existing spectral database methods often yield unsatisfactory results for heterogeneous particles.
Purpose of the Study:
- To present a novel methodology for identifying heterogeneous microparticles in drug products without prior purification.
- To demonstrate the combined use of multiple microspectroscopic techniques for comprehensive particle analysis.
- To investigate the root cause of a specific microparticle contamination event.
Main Methods:
- Utilized a combination of Raman microspectroscopy, infrared microspectroscopy, and energy dispersive X-ray microspectroscopy (EDX).
- Applied these techniques to analyze a heterogeneous microparticle directly, without chemical separation or purification.
- Employed spectral database search methods in conjunction with the complementary data from multiple techniques.
Main Results:
- Successfully identified a microparticle composed of four distinct compounds: polyisobutylene, hydrated magnesium silicate, titanium dioxide, and silica.
- The methodology enabled identification of the mixed particle components by integrating spectral data from Raman, IR, and EDX.
- The identified compounds suggest the microparticle originated from the vial stopper material.
Conclusions:
- The developed methodology effectively identifies heterogeneous microparticles by combining complementary microspectroscopic techniques.
- This approach overcomes limitations of traditional methods, particularly for small, mixed-component particles.
- The findings provide a root cause for a specific contamination issue, aiding in pharmaceutical quality improvement.
