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APACT 2004, 28 th April 2004

APACT 2004, 28 th April 2004. Comparison of Non-Invasive NIR and Raman Spectrometry and Broadband Acoustic Emission for the Monitoring of Powder Blending. L.J. Bellamy, J. Blasco Mata, A. Nordon, D. Littlejohn CPACT, University of Strathclyde, Glasgow, G1 1XL. Powder Blending Processes.

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APACT 2004, 28 th April 2004

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  1. APACT 2004, 28th April 2004 Comparison of Non-Invasive NIR and Raman Spectrometry and Broadband Acoustic Emission for the Monitoring of Powder Blending L.J. Bellamy, J. Blasco Mata, A. Nordon, D. Littlejohn CPACT, University of Strathclyde, Glasgow, G1 1XL

  2. Powder Blending Processes • Why Blend Powders? • Ensure unit homogeneity • Powders favour segregation (un-mixing) • Processing and Analysis • Often a short blending time • Crucial to other downstream processes • Analysis usually slow by comparison

  3. Incentives For PAT • Analytical Benefits • Real-time homogeneity determination • Potential for quantification of components • Quality Benefits • More consistent product • Tighter control of specification • Business Benefits • Increased quality and productivity • Fewer ‘wasted’ batches

  4. Non-Invasive Approach • Advantages • Removes errors associated with manual sampling • Reduced risk of contamination • Containment of dangerous materials • Disadvantages • Optical techniques require window • Number of sample points

  5. Instrumentation • Zeiss Corona 45 NIR Spectrometer • Kaiser PhATprobe Raman Spectrometer • Broadband Acoustic Emission System

  6. Instrumentation • Zeiss Corona 45 NIR Spectrometer • Non- invasive reflectance spectrometer • 128 element InGaAs array detector • 15 mm sample spot • Operated in absorbance mode • Spectra acquired every 0.5 s; average of 10 scans with 31 ms integration • Reflective white paper inside vessel

  7. Instrumentation • Kaiser PhATprobe • Non-invasive • 3 mm sample spot • 400 mW laser • 2 s spectral acquisition • Spectra acquired every 3 s

  8. Instrumentation • Broadband Acoustic Emission • Acoustic frequency spectrum up to 750 kHz • Agilient Oscilloscope • 2 MHz sample rate, 4000 points • Spectra acquired every 2 s

  9. Non-Invasive Monitoring

  10. Mixing Experiments • General Experimental Procedure • Major component loaded into vessel (microcrystalline cellulose or lactose) • Monitoring of single component before second component added to centre • Mixing is monitored for a further 10-15 minutes • Second components include: aspirin, citric acid, aspartame

  11. NIR Spectrum: Aspirin

  12. Raman Spectrum: Aspirin

  13. Acoustic Spectrum: Aspirin in Avicel

  14. Mixing Profile Generation • Near Infrared Spectrometry • First derivative (Savitsky-Golay, 5 pt second order polynomial) intensity against time - univariate • Raman Spectrometry • Second derivative (Savitsky-Golay, 23 pt second order polynomial) intensity against time - univariate • Acoustic Emission • Conversion to frequency domain power spectra • Plots of area under peaks in power spectra against time

  15. Mixing Profiles 30 g aspirin in 75 g Avicel PH-101 mixing at 50 rpm

  16. Investigations • Concentration of second component • Particle size effects on profile • Effect of particle shape • Multiple compound additions • Positioning of AE transducer

  17. NIR Mixing Profiles: 8956 cm-1

  18. NIR Calibration: Aspirin in Avicel Calibration at 8956 cm-1

  19. AE Calibration: Aspirin in Avicel Calibration for Area between 0 and 399.5 kHz

  20. PhATprobe Calibration: Aspirin in Avicel Calibration at 1604.7 cm-1

  21. Calibration Summary • Mixing profiles allow visualisation of progress • Univariate approach for optical data • Differences across spectral range • Multivariate techniques to be tested • Use of area for AE not ideal • Broad peaks in power spectra • Improvements in signal processing

  22. Influence of Particle Size • Important variable in blending processes • Size variations can effect blend stability • Problems caused in further processing • Validity of results • Potential applications in granulation end-point determination

  23. NIR Mixing Profiles

  24. NIR: Peak to Peak Noise at 8956 cm-1 Second overtone 7.5 g aspirin added to 75 g Avicel PH-101 800-900 s in profile

  25. PhATprobe: Mixing Particles Monitoring at 1607.4 cm-1

  26. 22.5 g citric acid added to 75 g Avicel PH-101 AE : Citric Acid in Avicel

  27. 22.5 g citric acid added to 75 g Avicel PH-101 0.5 – 53.2 kHz Sieve Range Mid-Point/ µm AE: Average Area (600-900 s)

  28. AE: Average Area (325-375 s) 22.5 g citric acid added to 75 g Avicel PH-101 0.5 – 53.2 kHz Sieve Range Mid-Point/ µm

  29. Particle Size Summary • Noise in profile shows increase with particle size for NIR and Raman, not AE • Effect observed for second overtone • Distribution of particles • AE signal magnitude increases with larger particles • Trend clearer just after addition

  30. Multi-Component Systems • NIR can be non-specific due to functional groups • Multivariate techniques required • Current AE data processing gives no species specific information • Indicates state of whole system • Raman can be used to monitor individual species • Large number of peaks available

  31. Raman Mixing Profiles Aspartame Peak 1005.6 cm-1 Aspirin Added Aspartame Added

  32. Instrumental Summary Table

  33. Instrumental Summary Table

  34. Conclusions • NIR and Raman spectrometry • Homogeneity, concentration and particle size information at low analyte levels • AE • Homogeneity determinations in multi-component systems and particle size • AE and Raman systems can be multiplexed

  35. Conclusions • AE monitoring would complement either NIR or Raman spectrometer • AE for multiple sample points • NIR/Raman for chemical information • Near-infrared monitoring being implemented at GSK Irvine • Trials in progress

  36. Future Plans • Particle Shape • Effects on trends already observed • Combinations of compounds • Determine if any particular types of compounds cause problems with mixing • Continuation of industrial trials at GSK • Pilot scale and plant implementation

  37. Acknowledgements • Dr Chris Killen, GSK • Gillian Millar and Ian Galloway, GSK • Clairet Scientific and Kaiser for the loan of the Raman PhATprobe spectrometer

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