Automated Particle Location and Chemical ID
- Fig. 1: Particle spectrum (green) obtained from Particlefinder analysis of injectable drug contaminants isolated on a nitrocellulose filter. This spectrum provides a match with a reference dolomite spectrum (red), a widely used industrial material, and a likely contaminant from structural concrete materials.
- Fig. 2: Optical image (left) and particle chemical classification (right) of pharmaceutical crystals on glass slide. Particles are classified as being 4-acetylsalicylic acid (red), 4-acetaminophen (green) and dust contaminant (blue).
In recent years Raman spectroscopy has seen a surge in popularity within many varied application fields. This is in no small part due to increased affordability and ease of use, coupled with growing awareness of the analytical advantages that Raman can offer against other comparable methods, such as FTIR and NIR. Non-destructive chemical specificity, tolerance to water and diffraction limited spatial resolution (for analysis of individual particles/features in the 0.5-1 µm size regime) are just some of the benefits.
Compact bench top systems are becoming increasingly common in laboratories, offering fast, targeted results across many application areas. A barrier to acceptance has been the relative complexity of the spectrometer, but maturation of the technique has been accompanied by significant improvements. Instruments are now truly multi-user friendly, with intelligent automation, and advanced user access control to present targeted functionality to users. Where Raman was domain of specialized research groups, now it is routinely applied by laboratories needing reliable answers fast.
Raman‘s molecular characterization can be easily applied to material identification, chemical characterization, and stability studies (with respect to time, temperature and humidity). Combination with the microscope opens up additional capabilities, allowing microscopic particles to be discretely targeted (e.g., contaminant identification, and more general troubleshooting), and micro/macro areas to be imaged for high contrast, chemical visualization of the sample. Their confocal performance allows sub-surface features to be analyzed in isolation e.g. identification of gas/liquid phase inclusions in minerals/glasses, and embedded particulates in resins and plastics.
The analysis of particulates has been long established within laboratories, whether to understand the physical structure of powders, or to assess particulate contaminant levels - the latter is particularly important in the pharmaceutical industry, where stringent requirements and protocols exist to qualify and quantify microscopic particles in injectable (parenteral) drugs. Such particle characterization techniques provide fast, reliable information about the count and morphology (shape/size) of particles.
However, what is missing in this is the question - what is the particle?
The new Particlefinder module combines reliable particle counting and morphological assessment with the fast chemical identification offered by Raman spectroscopy. On a single platform it is possible to automatically locate the presented particles, quantify them, characterize their morphology, and acquire Raman spectra from each one.
Troubleshooting within production plants can see significant time saving by employing particle-Raman analysis, identifying contamination sources robustly and quickly. Furthermore, particulate materials (such as powdered precursor chemical reagents, pharmaceutical drugs/excipients, and food stuffs) can be assessed, whether for reasons of quality assurance, or more fundamental research and development.
Such technology is seeing significant uptake in a number of fields, including pharmaceutical sciences, mining and geological exploration, and environmental assessments. Without doubt, growth of this new technology will continue, as laboratories embrace the unique capabilities it offers, above all, answering the analyst's question as quickly and simply as possible.