Raman Spectroscopy
Raman spectroscopy is a technique where a material interacts with a laser scattering light. Less than a percent of the scattered light will produce variance based on the molecular bonds’ vibrations within the material. With the spectrum obtained, caused by the variance in the scattered light, comparisons can be made between observed chemical structures and known structures for identification/confirmation of materials. In some cases, the spectral differences can even be used to compare polymorphism.
Raman spectroscopy is recognized by numerous standards and guidance agencies, including the ISO, ASTM, USP, and EP. This technique can analyze material on a dry or suspension/liquid basis. This technique has proven useful to various industries due to its ability to identify/compare materials.
A wide variety of sample types can be analyzed by Raman Spectroscopy, including active pharmaceuticals (APIs), excipients, contaminants, polymers, and polymorphs. Common applications include out-of-specification (OOS) investigations, generic formulation, contaminant investigation, finished product confirmation (specificity), and comparative studies.
Due to the complex nature studies relating to identification, PTL recommends reaching out to discuss your testing needs to evaluate the suitability of this analysis for your material.
Advantages
- Ability to potentially speciate particle size distribution within a mixture
- Targeted identification of contaminants or outlier particles
Considerations
- Particulate must be ~2 µm or larger in size, and scatter in the Raman spectra
- Not appropriate for metallic substances, or very dark or black materials
- This technique does not offer full chemical composition analysis
- Lower counts than image analysis
Sample Requirements
Ideal sample amount is up to 1 gram for solid samples.
For liquid samples, the preferred amount is 20 mL.
The above sample quantities are preferred. If sample availability is further limited, please contact us to share specifics about your sample and options for suitable sample quantities.
Detection Range
Particulate must be approximately 2 micrometers (µm) up to approximately 1300 µm in size to obtain Raman Spectroscopy results. Appropriate size range is dependent on Raman scatter of a material. The 2 µm minimum size threshold is based on high scattering materials.
Data Reported
A typical Raman Spectroscopy analysis will include the Raman spectra analysis of representative particles, comparison to the known spectra, and discussion about the results.
For MDRS, the particle size distribution analysis will be reported, counting at max 1,000 particles, based on suitability, as well.
Please contact us to learn more about the various reporting options.
Instrumentation
Particle Technology Labs uses the Malvern Morphologi 4-ID for our image analysis and Raman Spectroscopy testing.
