Laser diffraction methods

Iida Y, Ashokkumar M, Tuziuti T, Kozuka T, Yasui K, Towata A, Lee J (2010) Bubble population phenomena in sonochemical reactor I Estimation of bubble size distribution and its number density with pulsed sonocation - laser diffraction method. Ultrason Sonochem 17 473 179... 

Ultimately chemical images have the ability to show API adhering to other formulation excipients which is not possible by other sizing methods. Statistically, laser diffraction methods have less errors in the measurement as they measure millions of particle compared to the hundreds by Raman chemical imaging, but their lack of specificity means the whole sample is measured and not just the API. Ultimately the Raman method is still under development but provides the formulators of inhaled products an additional tool in understanding formulation properties and product. 

ISO 13320 Particle Size Analysis-Laser Diffraction Methods-Part 1 General... 

Sieves sieving and other sizing methods. In Draft of Standard Determination of Particle Size Distribution, Laser Diffraction Methods International Organization for Standardization (ISO) Berlin, Germany. 

Laser Diffraction Methods Over the past 30 years laser diffraction has developed into a leading principle for particle-size analysis of all kinds of aerosols, suspensions, emulsions, and sprays in laboratory and process environments. 

As indicated, Fraunhofer diffraction is a special case of Mie theory that can be used to obtain the volume of particles. The Malvern Instruments Model 2600c series of sizers (Malvern Instruments, Southborough, MA) use a laser diffraction method. The instruments are equipped with an IBM-compatible computer that controls the collection, manipulation, and presentation of data. The principle of operation is illustrated in Fig. 18. The instruments consist of a low-power laser transmitter and receiver detector units mounted 50 cm apart. Particles or spray... 

Provided that the emulsion does not undergo any flocculation, the coalescence rate can be measured simply by following the number of droplets or average diameter as a function of time. For this, a given volume of the emulsion is carefully diluted into the Isotone solution of the Coulter counter, and the number of droplets is measured. The average diameter can be obtained using laser diffraction methods (e.g., with the Master Sizer). By following this procedure at various time periods, the coalescence rate constant K can be obtained. 

The theory of Mie " is used also in the laser diffraction method for particle size analysis. r In this method, the light scattered by the particles is collected over a range of angles (usually between 1° and 20°) in the forward direction. The corresponding experimental setup is usually... 

Atkinson et al. (1992) have reported the use of a laser diffraction method to measure the particle size of drugs dispersed in ointments. In this study, they stressed the fact that a very small particle size was required to ensure efficacy of the drug. In addition, the size of the particles was especially important if the ointment was for ophthalmic use where particles must be less than 25 p,m. Whilst the particle size of the suspended particles can be assessed microscopically, laser diffraction offers a more rapid analysis. 

The laser diffraction method (e.g., Malvern analyzer) is among perhaps the most widely used technique for spray diagnostics. It is a line-of-sight method to measure the droplet size (Li, Nishida, and Hiroyasu 2004) by observing the diffracted light due to the presence of droplets in the laser probe (e.g., 10 mm diameter laser beam). 

Li, T., Nishida, K., and Hiroyasu, H. "Characterization of Initial Spray from a D.I. Gasoline Injector by Holography and Laser Diffraction Method." Atomization and Sprays 14, no. 5 (2004) 477-94. 

The particle size distribution of coarse abrasive materials (5 mm-50 pm) is determined by sieving. For particle sizes less than 50 pm, sedimentation and laser diffraction methods are used. 

BS ISO 13320 (2000) Particle size analysis - laser diffraction methods. British Standards Institution, London. 

The particle size distribution and mean particle size (dso) were determined by the laser diffraction method (FRITSCH Model ANALYSETTE 22, Idar-Obeistein, Germany). One gram of the sample was suspended with 10 ml bi-disdUed water, then the produced suspension (produced with hand shaking) was employed for measuring size analysis. The specific surface area (Sbet) as well as the pore volume of the powders was determined by BET method using a surface area analyzer (Autosoib-1, Quantachrome Instruments, USA). 

Particle size measurement techniques (Fig. 1) with various higher dispersion energies at very low (time-of-flight method) and at high silica aerosol concentrations (cascade impactor, laser diffraction method with air-jet injection) seem to be a powerful tool to investigate particle interactions. 

The ISO standard ISO 13320-1, Particle size analysis - Laser diffraction methods - Part 1 General principles, covers this method. 

Representation of results of particle size analysis - Part 1 Graphical representation Representation of results of particle size analysis - Part 2 Calculation of average particle sizes/ diameters and moments from particle size distributions Representation of results of particle size analysis - Part 3 Fitting of an experimental curve to a reference model (in preparation) Representation of results of particle size analysis - Part 4 Characterization of a classification process (in preparation) Representation of results of particle size analysis - Part 5 Validation of calculations relating to particle size analysis using logarithmic normal probability distribution (in preparation) Particle size analysis - Laser diffraction methods - Part 1 General principles... 

H. Pih and K. C. Liu, "Laser Diffraction Methods For High-Temperature Strain Measurements." was submitted to Experimental Mechanics for review and publication. 

In addition to the afore mentioned methods there are still special instrumental techniques applied such as the laser diffraction method for the determination of the particle size and the gas permeability method for the determination of the specific surface of a powder [17]. A further discussion of these methods is beyond the scope of this book. More information is available in textbooks [18]. 

The laser diffraction method [57] was employed to experimentally determine the crystal structure within the flbrillated columns by using a uniform glass microsphere/silicone oil system, and a bet structure was observed as predicted. The diffraction pattern is shown in Figure 7 for monodispersed glass beads of various sizes. The structure constants determined from the laser diffraction experiment were found to agree very well with the theoretical calculation based on dipolar interaction energy. Table 4 lists the experimentally determined and theoretically calculated structure constants for the bet structure formed by the silica spheres. The experimental data are consistent witli the proposed bet structure. 

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