Laser Diffraction
Laser Diffraction (also known as Static Light Scattering) is one of the most widely used particle sizing distribution techniques. Samples, which can be analyzed either as a liquid suspension or a dry dispersion, are passed through a laser beam, scattering the light. Detectors placed at fixed angles measure the intensity of light scattered at each position, and a mathematical model (Mie or Fraunhofer Theory) is then applied to generate a particle size distribution. The final result is reported on an Equivalent Spherical Diameter Volume basis.
Particle Size by Laser Diffraction is recognized by numerous standards and guidance agencies, including the ISO, ASTM, USP, EP and JP. This technique’s ability to perform dry or liquid dispersion analyses make it a good choice for general particle sizing applications, and its broad dynamic range (submicron to millimeters) has proven useful to industries including environmental, pharmaceutical, food, health, and beauty industries.
A wide variety of sample types can be analyzed by Laser Diffraction, including active pharmaceuticals (APIs), excipients, flyash, turbid wastewater, and environmental emission samples. Common applications include QA/QC batch testing, general survey screening measurements, and comparative studies.
Advantages
- Widely used particle sizing distribution technique
- Analyzed as liquid suspension or a dry suspension
- Broad Dynamic Range; submicron to millimeters
- Several laser diffractors onsite by multiple manufacturer to ensure best fit for material
Considerations
- Low resolution technique not a fit for analyzing low quantity outlier population
- Not suitable for elongated or fiber-like material
- Concentration dependent
- Heterogenous material cannot be distinguished
Sample Requirements
Sample amount is not an easy question to answer, since it depends on the particle size, morphology, and general nature of the material, as well as the technique that will be used. Ideal sample amount is 5-10 grams for solid samples especially for new material to allow for determination of an adequate preparation and instrument settings. For liquid samples the preferred amount is 250 mL if the sample is to be analyzed as-received.
We are often able to analyze very small amounts of sample material. Questions on sample needs please contact us to share specifics about your sample and options for suitable sample quantities.
Detection Range
PTL’s Laser Diffraction Department can measure particulate from approximately 0.02 micrometers (um) up to 3500 micrometers (um) depending on the instrument model used. Detection range also varies with the dispersion method. The wide analytical range allows for laser diffraction to be a popular option for general particle size determination.
Data Reported
While each data output may cosmetically look a little different, the general content of the reports is all the same. A comprehensive summary including the general graphical particle size distribution on a volume-weighted basis will be provided, as well as the most commonly requested parameters (10th, 50th and 90th percentiles, etc.). Information on specific sizes can be reported on request.
Instrumentation
Particle Technology Labs has some of the top players in the industry, such as Malvern Panalytical, Beckman Coulter, and Sympatec to ensure we find the correct instrumentation for your material. This method has been used extensively in many industries including pharmaceutical, environmental, food, health, beauty and others. Sample material is passed through a laser beam resulting in the laser light scattered at a wide range of angles. Detectors measure the intensity of light scattered at that position. A mathematical model (Mie or Fraunhofer Theory) is applied to generate a particle size distribution. The final result is reported on an Equivalent Spherical Diameter Volume basis.
Malvern Panalytical Mastersizer 3000
Sympatec Helos
