Troubleshooting Laser Diffraction Particle Size Data

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Troubleshooting Laser Diffraction Particle Size Data

  1. 1. Troubleshooting Laser Diffraction Particle Size Data Ian Treviranus ian.treviranus@horiba.com www.horiba.com/us/particle© 2011 HORIBA, Ltd. All rights reserved.
  2. 2. Plan of Attack  Typical workflow  Calculation optimization  Hardware optimization  LA-950 data analysis tools  Q&A© 2011 HORIBA, Ltd. All rights reserved.
  3. 3. Typical Workflow Compatible technologies? YES  Compare Conditions NO  How are they different Compare Conditions SAME  Investigate scattering pattern DIFFERENT  Are differences relevant for this material? – YES  Re-test with new conditions – NO  Investigate scattering pattern When you hit a wall  Ask the experts!© 2011 HORIBA, Ltd. All rights reserved.
  4. 4. Compatible Technologies Different technologies measure different material properties Ideally the comparison is apples to apples – Different instruments of same technology are close enough (Gala to Fuji) Diffraction to SEM (or similar) is like apple to oranges and must be approached differently – Different technologies gives you more information, not necessarily bad© 2011 HORIBA, Ltd. All rights reserved.
  5. 5. SEM Image© 2011 HORIBA, Ltd. All rights reserved.
  6. 6. LA-950 Result SEM data alone makes us think this is the size range© 2011 HORIBA, Ltd. All rights reserved.
  7. 7. Plan of Attack  Typical workflow  Calculation optimization  Hardware optimization  LA-950 data analysis tools  Q&A© 2011 HORIBA, Ltd. All rights reserved.
  8. 8. Compare Conditions First, check calculation conditions Refractive Index: real and imaginary Distribution Base: volume is best Iterations: wide or narrow size range Second, check hardware conditions Concentration: transmittance Particle support: pumping Dispersion: US for wet, air pressure for dry Duration: wide distributions© 2011 HORIBA, Ltd. All rights reserved.
  9. 9. Refractive Index Seemingly minor differences calculate different distributions© 2011 HORIBA, Ltd. All rights reserved.
  10. 10. Distribution Base Volume basis by default Excellent for mass balancing Number basis recalc  significant error Number Volume Area© 2011 HORIBA, Ltd. All rights reserved.
  11. 11. Plan of Attack  Typical workflow  Calculation optimization  Hardware optimization  LA-950 data analysis tools  Q&A© 2011 HORIBA, Ltd. All rights reserved.
  12. 12. Compare Conditions First, check calculation conditions Refractive Index: real and imaginary Distribution Base: volume is best Iterations Second, check hardware conditions Concentration: transmittance Particle support: pumping Dispersion: US for wet, air pressure for dry Duration: wide distributions© 2011 HORIBA, Ltd. All rights reserved.
  13. 13. Concentration High enough for good S/N ratio Low enough to avoid multiple scattering Typically 95 – 80 %T Measure at different T%, look at Chi Square calculation d50 Chi2 © 2011 HORIBA, Ltd. All rights reserved.
  14. 14. Pump & Stirrer Must be high enough to suspend Exp # 1 Agitation Circulation 1 1 Dmean (nm) 187.03 D10 (nm) 137.5 D90 (nm) 245.7 & circulate heavy particles 2 1 3 184.23 135.9 242.1 Not so high that bubbles are 3 3 1 187.28 137.8 245.8 4 3 3 184.61 136.1 242.5 introduced 5 6 1 1 1 3 185.32 184.04 136.3 135.8 243.7 241.8 Adding energy – can disperse 7 3 1 184.13 135.8 241.9 8 3 3 184.98 136.4 242.9 loose agglomerates Parameters Selected: Agitation: 2 Circulation: 2 Measure at several settings & select optimum Can be automated in software (see right) © 2011 HORIBA, Ltd. All rights reserved.
  15. 15. Ultrasonic Dispersion Adding energy to break up agglomerates – disperse to primary particles, without breaking particles Similar to changing air pressure on dry powder feeder Typically set to 100% energy, vary time (sec) on Investigate tails of distribution  High end to see if agglomerates removed  Small end to see if new, smaller particles appear (breakage) Test reproducibility, consider robustness Note:  Do not use on emulsions  Can cause thermal mixing trouble w/solvents - wait  Use external probe if t> 2-5 minutes© 2011 HORIBA, Ltd. All rights reserved.
  16. 16. Measurement Duration Long enough for reproducibility Typically 5 sec, up to several minutes Longer time for large, broad distributions Can be automated in software© 2011 HORIBA, Ltd. All rights reserved.
  17. 17. Examples© 2011 HORIBA, Ltd. All rights reserved.
  18. 18. Plan of Attack  Typical workflow  Calculation optimization  Hardware optimization  LA-950 data analysis tools  Q&A© 2011 HORIBA, Ltd. All rights reserved.
  19. 19. LA-950 Method Expert© 2011 HORIBA, Ltd. All rights reserved.
  20. 20. Method Expert Hardware There are four important tests… Circulation Concentration Dispersion Duration© 2011 HORIBA, Ltd. All rights reserved.
  21. 21. Method Expert Calculation There are two important tests… Real RI Imaginary RI© 2011 HORIBA, Ltd. All rights reserved.
  22. 22. LA-950 Method Expert Why is the test important? What does the test do? How will the results be displayed? What is the best value? User selects up to 5 values for testing© 2011 HORIBA, Ltd. All rights reserved.
  23. 23. LA-950 Method Expert Method Expert guides user to prepare the LA-950 for each test Results displayed in multiple formats: PSD, D50, R-parameter© 2011 HORIBA, Ltd. All rights reserved.
  24. 24. LA-950 Method Expert© 2011 HORIBA, Ltd. All rights reserved.
  25. 25. LA-950 Method Expert© 2011 HORIBA, Ltd. All rights reserved.
  26. 26. Intensity Graph Diffraction analyzer measures light scattering pattern, algorithm transforms this into a particle size distribution© 2011 HORIBA, Ltd. All rights reserved.
  27. 27. Size affects intensity  LARGE PARTICLE:  Low angle scatter  Large signal Wide Pattern - Low intensity  SMALL PARTICLE: Narrow Pattern - High intensity  High Angle Scatter  Small Signal© 2011 HORIBA, Ltd. All rights reserved.
  28. 28. Intensity Graph© 2011 HORIBA, Ltd. All rights reserved.
  29. 29. For More Information Visit www.horiba.com/us/particle Previously recorded webinars: -- LA-950 Method Expert Software -- Understanding and Interpreting Your PSA Results -- Setting Attainable Size Specifications -- “Boot Camp” Laser Diffraction 6-part Training Course Many application and technical notes Ask a question at labinfo@horiba.com Keep reading the monthly HORIBA Particle e-mail newsletter! Visit the Download Center to find the video from this webinar.© 2011 HORIBA, Ltd. All rights reserved.
  30. 30. Plan of Attack  Typical workflow  Calculation optimization  Hardware optimization  LA-950 data analysis tools  Q&A© 2011 HORIBA, Ltd. All rights reserved.

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