Scanning Electron Microscopy (SEM)

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Popularly used for:

  • Determination of number particle size distribution of small particles
  • Statistical evaluation of Particle shape, e.g. aspect ratio (ratio between breadth and length), gives valuable extra information complementary to laser diffraction about particle characteristics.
  • Observation and identification of foreign particles in the sample (pollution). USe elemental analysis by EDX to confirm Suspicion of corruption by foreign particles
  • Cryo SEM for globule size
  • Search evidence of crystallisation in amorphous materials
  • Reverse engineering
  • Observe surfaces, pores, and other small features of submicron- and nanostructure of particles
  • Obtain elemental mapping of the sample; this can help identify particles of API in the matrix of excipients.                 

For Material Experts: Instrument and measuring principle

Particle Analytical applies a Scanning Electron Microscope equipped with detectors for Secondary Electrons and Backscatter Electrons. The backscatter detector designed to analyse for differences in molecular density. With the backscatter detector, it is possible to visualise, e.g. compositional density differences in a granule or tablet. 

InstrumentScanning Electron Microscope
USP/Ph. Eur.USP 1181/ Ph.Eur. 2.9.52 (non-GMP)
Sample requirementThe substance or the object must be coated with conducting material (e.g. Au or C) to conduct electrons (sputter-coating). The sample must be dry.
Sample amountA few mg
ResultImages of the compound at different magnifications

Consult our Experts

Dr. Wenbo Wang
QC Chemist

Dr. Anna Shevchenko
Principal Scientist

Literature

Carlton RA (2011) Pharmaceutical Microscopy. Springer Science & Business Media

Cheney B (2007) Introduction to scanning electron microscopy. Materials Engineering Department San Jose State University. 2007.

McMullan D (1995) Scanning electron microscopy 1928–1965. Scanning 17(3):175-85.

Vernon-Parry KD (2000) Scanning electron microscopy: an introduction. III-Vs Rev 13(4):40-4. 

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