Particle Size and Shape Analysis/Image Analysis
Image analysis is a powerful analytical technique that provides particle shape information in addition to a sample’s standard particle size distribution. This technique captures digital images of dispersed particles utilizing an appropriate objective/magnification and CCD camera.
Instrument software assigns a greyscale value to the pixels within the digital images and the operator evaluates the images to differentiate between particles and background. This process is known as “thresholding” and based on the value set by the operator, the pixel is turned on or off. Each digital image is then processed by the software, and, once complete, results are available on a variety of size and shape parameters such as Equivalent Circular Area (ECA) Diameter, Length, Width, Aspect Ratio, Circularity, Convexity.
Static imaging systems offer versatility in that various sample states can be analyzed: dry powders, liquid suspensions, particulate captured on filters or films, in addition to creams and lotions. Particle size and shape using this technique is also supported by several standards and guidance agencies including ISO and USP, making it useful to a broad range of industries.
Advantages
- Provides shape distributions along with commonly reported number and volume-weighted particle distributions
- Captures images of particles allowing for visualization
- In some cases, different particle types within a sample can be assessed individually
- Non-spherical, elongated particles can be reported with more appropriate outputs
Considerations
- Long analysis times are typically required to provide representative results
- Not recommended for samples with excessively low particle concentrations
- Some sample optical properties may not be suitable for this technique
Sample Requirements
Ideal sample amount is 1 gram for solid samples and 20 mL for liquid samples.
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
Typically, particulate from approximately 0.5 microns to up to 1000 microns can be imaged. Actual range of detection may differ. The most appropriate objective is selected for each sample resulting in smaller or larger minimum and maximum detection sizes.
Data Reported
A comprehensive summary including particle size distribution histograms on both a CE Diameter number and volume-weighted basis will be provided. Default shape outputs include histograms for aspect ratio and circularity. Commonly requested distribution statistics (means, 10th, 50th, 90th percentiles, etc.) are summarized. Each sample also receives a particle image report, providing a “snapshot” of the particles detected.
Information on specific populations, size ranges, and other parameters may be possible which can be reported on request.
Instrumentation
Particle Technology Labs uses the Malvern Morphologi 4-ID for our image analysis testing.
Malvern Morphologi 4-ID
