Top 10 Dry Method Development Tips

  1. Design every method for maximum precision: repeatability and reproducibility.
  2. Study different sampling techniques to help minimize error. This is particularly important for materials with small outlier populations. 
  3. Dry measurements fall into two approaches: measurement everything on the chute or acquire multiple measurements from the same sampling. The former must be done when the material has a sampling bias. The latter may be used when the material does not exhibit a sampling bias. Know which approach is required for your material.
  4. Always use feedback control on the LA-960 PowderJet.
  5. Increase dispersion energy by using a smaller nozzle for the PowderJet.
  6. Choose a refractive index by studying references (i.e. CRC Handbook), applying known information about the material, or, if no information is available, by minimizing the R-parameter.  
  7. Refractive index (RI) affects the accuracy of the particle size distribution, but has a much smaller effect on the analyzer's ability to detect changes to that distribution. In practice, even an incorrect RI can be used to successfully monitor the quality of a material or process.
  8. Study the effect of air pressure on the material. Pay close attention to the coarsest and finest parts of the distribution to evaluate the extent of de-agglomeration and onset of particle breaking. 
  9. Evaluate the method's robustness by calculating the coefficient of variation for the D10, D50, and D90 values across a minimum of three measurement results. The LA-960 automatically makes these calculations.  
  10. Evaluate the method's suitability by confirming that "good" and "bad" lots of material show a difference in particle size distribution.

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