Particle size analysis microscopy

Chamberlain, E. K. 1996. Characterization of heated and thermally processed cross-linked waxy maize starch utilizing particle size analysis, microscopy and rheology. M. S. Thesis, Cornell University, Ithaca, NY. 

Analysis. Excellent reviews of phosphate analysis are available (28). SoHds characterization methods such as x-ray powder diffraction (xrd) and thermal gravimetric analysis (tga) are used for the identification of individual crystalline phosphates, either alone or in mixtures. These techniques, along with elemental analysis and phosphate species deterrnination, are used to identify unknown phosphates and their mixtures. Particle size analysis, surface area, microscopy, and other standard soHds characterizations are useful in relating soHds properties to performance. SoHd-state nmr is used with increasing frequency. 

Surface Area and Permeability or Porosity. Gas or solute adsorption is typicaUy used to evaluate surface area (74,75), and mercury porosimetry is used, ia coajuactioa with at least oae other particle-size analysis, eg, electron microscopy, to assess permeabUity (76). Experimental techniques and theoretical models have been developed to elucidate the nature and quantity of pores (74,77). These iaclude the kinetic approach to gas adsorptioa of Bmaauer, Emmett, and TeUer (78), known as the BET method and which is based on Langmuir s adsorption model (79), the potential theory of Polanyi (25,80) for gas adsorption, the experimental aspects of solute adsorption (25,81), and the principles of mercury porosimetry, based on the Young-Duprn expression (24,25). 

Triplicate aliquots were taken for particle size analysis and two of those aliquots were mixed for BET surface area analysis results are in Table III. The nine samples were individually sieved for size distribution. A chi-squared test was performed on each triplicate set in order to check the apparent efficiency of composite mixing. For all three composite samples, there was a 90 percent probability that each of the three replicates from each composite sample came from the same population. The A and C samples were combined and evaluated for surface area by nitrogen adsorption (BET). The B samples were then subjected to scanning electron microscopy (SEM) analysis. 

X-ray powder diffraction data may be helpful but are often hard to interpret for complex mixtures use of computer data file search programs (6) and microcamera methods for single particle analysis (7) may be useful for identification. Comparative sample identification is generally less often possible than for metals since the latter are manufactured while the nonmetallic inorganic solids are often unprocessed materials with large property variations. However, where applicable, the following are some examples of determinations which might be made (a) particle size by microscopy (b) microstructure and sub-microstructure characterization... 

In colloidal suspensions of anisotropic particles, the static structure factor plays a prominent role in particle size analysis. We have used transient electric birefringence (TEB) and electron microscopy, in addition to laser light scattering, to correlate our analysis of particle size distributions of bentonite suspensions. The complementary nature of TEB and photon correlation spectroscopy (PCS) in particle size analysis will be discussed. 

Data from a number of different particle size analysis instrumental methods including light scattering, field flow fractionation, hydrodynamic chromatography and microscopy were obtained for a series of polymethylmethacrylate latexes and were compared to DCP results (2). These and other comparative results have demonstrated the accuracy of the instrument and method. The reproducibility and precision of the instrument also were studied and are reported elsewhere ( 1 ). 

In developing an analysis of this type, it is desirable to establish correlation with a widely accepted technique. This was done by determining particle size during polymerization by the polymerization rate technique and submitting the final latex for particle size analysis by electron microscopy. 

Relevant national standards are available covering particle size analysis by microscopy. BS 3406 Part 4 [11] is the British Standard guide to optical microscopy. The American standard ASTM E20 was discontinued in 1994 [12]. ASTM 175-82 [13] is a standard defining terminology for microscope related applications. ASTM E766-98 [14] is a standard practice for calibrating the magnification of an SEM. NF XI1-661 [15] is the French standard for optical microscopy. NF XI1-696 [16] covers... 

These, and other techniques, may be applied in electron microscopy to permit chemical assay and particle size analysis to be run concurrently [179]. 

Sol-gel silica particles of four different sizes, viz. 0.2 pm, 0.5 pm, 1.0 pm and 1.5 pm were obtained from Geltech Corporation. Particle size analysis on the slurries was carried out using a Honeywell Microtrac UPA 150 particle size analyzer, which utilizes the dynamic light scattering technique. In addition. Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) was also used for determining particle size and shape. 

Following the progression of particle size analysis, so far we have gotten a perfect sample, uniquely characterized the particle size and done the statistical parameter estimates now we have the tools to look at actual data and methods of measurement. There are many methods for the characterization of particle size and shape however, in this section we will only include methods commonly used by researchers in tableting. The methods covered are microscopy, sieving, and laser diffraction. 

Particle size analysis should be carried out on all batches of salt candidates to establish suitable recrystallization procedures. A rapid assessment of both the particle size and crystal habit can be carried out by Scanning Electron Microscopy (SEM). Laser diffraction techniques can provide a rapid assessment of the particle size distribution using less than lOmg of material. It is also useful to retain a photomicrograph for each batch. 

The characterization of the physical properties of pharmaceutical compounds under development is often conducted using a variety of techniques including DSC, TGA, XRD, HSM, solid-state nuclear magnetic resonance (NMR), infrared (IR) and Raman spectroscopy, moisture uptake, particle size analysis, scanning electron microscopy (SEM), and micromeritic assays. A typical initial analysis of a pharmaceutical compound under development in a materials characterization group would include DSC, TGA, HSM, and XRD analyses. These four techniques are chosen because the data generated from them, when viewed collectively, comprise a relatively complete initial analysis of the physical properties of the compound. The DSC, TGA, and HSM assays... 

Washington (1992) has discussed the concepts and techniques of particle size analysis and its role in pharmaceutical sciences and other industries. There are many different methods available for particle size analysis. The techniques most readily available include sieving, optical microscopy in conjunction with image analysis, electron microscopy, the Coulter Counter and laser diffractometers. Size characterization is simple for spherical particles, but not for irregular particles where the assigned size will depend on the method of characterization used. Table 6.2 lists particle size measurement methods commonly used and the corresponding approximate useful size range (Mullin 1993). 

This section of the chapter is divided into two parts. The first part discusses the instruments and methods used to evaluate particle morphology. It pays particular attention to nomenclature since the words used in this field are often ambiguous. The second part deals with the details of particle size analysis by microscopy. It pays particular attention to sampling issues and to the use of image analysis. 

Sampling is by far the most important part of particle size analysis by microscopy (and probably all particle size techniques). A kilogram of drug substance will contain many millions of particles. Since, at most, the particle size analysis samples a few thousand particles, the measured particles must be selected with care. Allen [20] presents an extensive discussion of bulk sampling issues relevant to all particle size analysis, irrespective of the particular technique. Our interest, though, is primarily directed toward sampling as it relates to the specimen used for particle size analysis by microscopy. We will assume that the 50 mg or so of sample dehvered to the laboratory is truly representative of the bulk powder. 

This section has presented a few of the methods and applications of particle size analysis using microscopy and image analysis. The technique has gained... 

This chapter has presented a survey of some of the ways that microscopy can aid in the development of pharmaceuticals. Microscopy can make important contributions to the solid-state characterization of the drug substance, to particle size analysis, and to contaminant identification. It is often joked, though, that the most important instrument in microscopy lies just above the eyepieces - a skilled, well-trained microscopist. It is no joke that the techniques described in... 

Appropriate particle size analysis methods with very low shear stress (free settling with particle image velocity, field emission scanning electron microscopy, fluidized bed or vibrating sieve feeding with laser diffraction) have been tested for their reproducibility and minimal dispersion energy. 

Spectrometry Overview. Mercury. Microscopy Techniques Scanning Electron Microscopy X-Ray Microscopy. Particle Size Analysis. Polychlorinated Biphenyls. Polycyclic Aromatic Hydrocarbons Environmental Aj li-cations. Radiochemical Methods Overview. Sample Handling Sample Preservation. Sampling Theory. Surface Analysis Auger Electron Spectroscopy. Tin. X-Ray Absorption and Diffraction Overview. X-Ray Fluorescence and Emission Energy Dispersive X-Ray Ruores-cence Particle-Induced X-Ray Emission. 

See also-. Chiroptical Analysis. Microscopy Overview. Microscopy Techniques Specimen Preparation for Light. Optical Spectroscopy Refractometry and Reflectometry. Particle Size Analysis. 

Ultrafiltration. Microscopy Applications Environmental Light Microscopy Electron Microscopy Specimen Preparation for Electron Microscopy Scanning Electron Microscopy Atomic Force and Scanning Tunneling Microscopy. Particle Size Analysis. Sampling Theory. 

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