Laser Diffraction Particle Size Analysis (PSA)

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Two identical batches of catalysts (numbered 3 and 4) were placed in a reactor for differing lengths of time (Batch 4 had the longer reactor time). The laser-diffraction PSA size distribution from both batches are overlaid to show increased prevalence of smaller particles (0.1 - 10 micron equivalent spherical diameter) in Batch 4.

Laser Diffraction particle size analysis (PSA) is an indirect, optical technique that measures particle size distributions – by equivalent spherical diameter (D10, D50, D90) – in liquid and solid samples.

Strengths

Particle size measurement is not impacted by flow behavior
Rapid measurement
Minimal sample preparation

Limitations

Accurate interpretation requires some up-front understanding of particles’ morphology
Semi-quantitative
Not able to determine particle shape

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Example Outputs Instruments Used How PSA Works

Laser Diffraction Particle Size Analysis Services

Laser Diffraction Particle Size Analysis

Laser Diffraction particle size analysis (PSA) is an indirect, optical technique that measures particle size distributions – by equivalent spherical diameter (D10, D50, D90) – in liquid and solid samples.

Sample Requirements

Maximum Particle Diameter: 2500 µm
Minimum Particle Diameter (Dry): 0.1 µm
Minimum Particle Diameter (Wet): 0.04 µm

Example Outputs

Two identical batches of catalysts (numbered 3 and 4) were placed in a reactor for differing lengths of time (Batch 4 had the longer reactor time). The laser-diffraction PSA size distribution from both batches are overlaid to show increased prevalence of smaller particles (0.1 – 10 micron equivalent spherical diameter) in Batch 4.

From: Anton Paar

Instruments Used

Anton Paar LD-1100

Particle Size Measuring Range: 0.1 µm to 2500 µm
Repeatability: < 1%
Particle Size Accuracy: < 3%
Dry Jet Dispersion (DJD) technology to prevent agglomerate formation and improve accuracy

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How PSA Works

In a PSA measurement, an incoming laser beam is cast upon particles suspended in solution, each of which diffract photons from the incident beam. Interferences in the diffracted light generate a pattern detected with an optical sensor. This diffraction pattern can be generated within one second; making raw data collection extremely fast.

Once the pattern is recorded, it can then be analyzed using Fraunhofer or Mie theories of optics, which correlate measured intensity of the diffracted light to particle size: bigger particles produce narrower diffraction rings. This correlation allows analysts to deconstruct a dataset of 2D laser diffraction patterns into 1D intensity curves plotted as a function of particle size, yielding a volume-based size distribution for all particles in the sample.