Raman Spectroscopy
Raman Spectroscopy provides a high level of chemical specificity required to identify components in a sample, even differentiating between alternative forms of the same compound. Coupled with automated static image analysis capable of measuring particle size and shape, this technology makes for a powerful high-resolution analytical tool when characterizing particles. Morphologically Directed Raman Spectroscopy (MDRS), is used in many applications including:
• Determining particle morphology and composition of a component in a mixture, such as API particle size in a pharmaceutical formulation, generic drug development or cement research. The ability to exclude particles based on their composition allows for population isolation of particle size data through speciation.
• Identifying contaminants or outlier particles in a failing batch of material. Determining the composition of the contaminants can then allow determination of the origin source.
• Investigating unknown particulate samples such as the mineral composition of geological samples.
When an analysis is performed on the sample material, particles are measured for size and shape, and then particle classes are created. A morphological description of each identified particle can then be generated in the form of size and shape distributions using the data from the image analysis measurement. If a specific component is of interest, particles with a distinct morphology such as size range or shape parameters can be targeted for chemical analysis using Raman spectroscopy. The location of individual particles on the sample slide is recorded during the image analysis measurement. The instrument can then return to collect the Raman spectra of individual particles for identification against a spectral library.
MDRS is particularly well-suited to a wide range of organic and inorganic materials. Some sample materials are unsuitable for this type of analysis including metals, very dark or black samples, and samples which fluoresce at the wavelength of the laser light used (785 nm).
This technology is offered utilizing one of our newest instruments, the Malvern Morphologi 4-ID that couples Raman spectroscopy speciation with image analysis. This combination of analytical techniques allows comprehensive results and solutions to complex characterization problems.
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.
