Near-infrared spectroscopy and imaging for the monitoring of powder blend homogeneity

Arwa S. El-Hagrasy, Hannah R. Morris, Frank D'Amico, Robert A. Lodder, James K. Drennen

Research output: Contribution to journalArticlepeer-review

189 Scopus citations


In-process testing requirements for adequacy of mixing are established in 21 CFR 211.110(a)(3). Considering also, the U.S. Food and Drug Administration's draft guidance published in 1999 (Guidance for Industry, ANDAs: Blend Uniformity Analysis;, the importance of when and how to perform blend uniformity analysis is obvious. Near-infrared (NIR) spectroscopy was used noninvasively, in this study, to monitor powder blend homogeneity. Powder mixtures consisting of salicylic acid and Fast-Flo lactose were blended in an 8-qt. V-Blender. Optical ports installed at six positions on the blender allowed spectral collection using fiber optics. A traditional thief probe was used to collect powder samples for ultraviolet (UV) reference analysis. The blender was stopped at preselected time points for collection of NIR and UV data. Several algorithms and sampling protocols were studied to identify an optimum methodology for blend homogeneity determination. The blending process was also monitored with an InSb imaging camera for comparison with the traditional NIR spectroscopy and UV reference data. Data analysis indicates that multiple sampling points were essential for accurate and precise estimation of mixing and points. Moreover, multiple runs of identical blends often display homogeneity at unique and points, thus demonstrating the potential advantage of monitoring every blend.

Original languageEnglish
Article number50003805
Pages (from-to)1298-1307
Number of pages10
JournalJournal of Pharmaceutical Sciences
Issue number9
StatePublished - 2001


  • Blend uniformity analysis
  • Homogeneity
  • Imaging
  • NIR (near-infrared)
  • Process control

ASJC Scopus subject areas

  • Pharmaceutical Science


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