Physical Pharmacy 25 Liposome PL-PSDA (Polymer Lab: HDC mechanism) What is the volume average diameter? What is the polydispersity index?
Physical Pharmacy 26 Sieving POWDER can be separated into various size fractions by vibrating sieve loaded with sample to enable the particles of size less than that of the mesh openings to pass through and the over size to remain in the sieve. Dry sieving is adopted for free flowing powder samples of size range varying from e.g. 4mm down to 25μm.
Physical Pharmacy 27 Sieves A standard test sieve is generally made of a woven wire mesh cloth specified wire thickness with square openings Standard sieves are made according to recommended norms to maintain opening size interval between successive sieves. The ratio between successive sieves is kept as a constant such as and hence the sieve size varies in geometric progression. fixed to a rectangular or circular frame
Physical Pharmacy 28 Sieving procedure Sieves stacked pan a b c d e f g Wire mesh Minimum size Maximum size
Physical Pharmacy 29 Table of Sieve Results
Physical Pharmacy 210 Interpretation of Sieve Results From the % cumulative weight, the mean diameter can be obtained i.e. d(0.5) – the diameter at which 50% of the samples, based on weight falls below it. Weight (%) Cumulative weight (%)
Microscopy Microscopy Physical Pharmacy 211 To fly, moths must be light. A close-up of the Cecropia Moth scale shows that it is mostly air, adding very little weight to the moth The deer tick, is about the size of a freckle. The shells of radiolarians, single-celled animals.
Physical Pharmacy 212 Principles of Microscopy Principles of Microscopy
Physical Pharmacy 213 Using light microscopy equipped with graticule to determine size
Comparison of microscopes FeatureLightTEMSEM UsemorphologySmall particles, nm morphology Source of illumination Visible lightHigh speed electrons Best resolution200 nm0.2 nm3-6 nm Magnification X ,000X20-150,000X Depth of field nm mm Lens typeGlassElectromagneticElectromagnet Image ray- formation spot On eye by lenses On phosphorescent plate by lenses On cathode tube by scanning device Physical Pharmacy 214
Physical Pharmacy 215 Scanning Electron Microscope
Physical Pharmacy 216 SEM Technique
Inside the SEM Physical Pharmacy 217
Physical Pharmacy 218 Information given by SEM
Physical Pharmacy 219 References SL Flegler, JW Heckman, KL Klomparens, Scanning and transmission electron microscopy, Oxford, New York (1993) ghthome.html