Calibration aerosols, generation

The DOP aerosol generator is compressed-air operated, equipped with Laskin-type nozzles. The aerosol photometer is a light-scattering type with a threshold sensitivity of at least 10 mg/1, capable of measuring concentrations in the range of 80 to 120 mg/1, and with air sample flow rate of 1 ft + 10% per min. This instrument is to be calibrated per manufacturer recommendation. 

The DMA was originally intended to be used as a monodisperse aerosol generator to produce submicrometer-sized aerosols for testing and calibration. However, it is used more commonly to measure particle size distribution with high resolution in the submicrometer size range. By monitoring the exit aerosol stream with a CNC (see Section 13.6), the number concentration in a narrow range of mobilities, and thus the particle size, can be determined. The entire submicrometer particle size dis-... 

Calibration of these single-particle counters is usually carried out using monodisperse polystyrene latex or polyvinyl latex spheres, which are available in sizes from 0.1 to 3 /im and have a refractive index of 1.6 alternatively, aerosols with lower refractive indices may be generated from liquids such as dioctyl phthalate (m = 1.49). Whitby and Willeke (1979) discuss the... 

Calibration of the instruments to measure the size distribution and chemical composition requires methods of generating aerosols of well-defined sizes and known composition. Generating aerosols of known... 

Marple VA, Olson BA, Santhanakrishnan K, et al. Next generation pharmaceutical impactor a new impactor for pharmaceutical inhaler testing. Part HI. Extension of archival calibration to 15 IVmin. J Aerosol Med 2004 17 335-343. 

Much effort and ingenuity have gone into the development of generators capable of producing monodisperse aerosols, and several are discussed at the end of this chapter. These are used for the testing of gas-cleaning equipment, the calibration of si .e measurement devices, and basic studies of aerosol behavior. 

Ultrasonic devices have been extensively used to process sol-gel precursor solutions, e.g. precursor dispersion in liquid solution. Besides, several works report on the fabrication of calibrated powders from ultrasonically sprayed sol-gel precursors (process D, according to classification by Vigui6 and Spitz). The sol-gel fabrication of micro-lenses from a drop-on-demand ultrasonic nozzle (ink-jet type) was also studied in details (Biehl, 1998 Danzebrink, 1999, 2001). However, in this latter case, no aerosol was formed. When considering the use of an ultrasonically generated aerosol, it appears that very few works... 

Figure 6.17. Typical data generated by the Amherst Process Instruments Inc. Aerosizer for aerosol systems, and powders aerosolized prior to characterization smdies. a) Calibration using aerosols of standard latex spheres of known size, b) Characterization of a mixture standard of polystyrene latex spheres, c) Characterization of a sample of 5 micron silica microspheres mixed with a small number of 10 micron microspheres. D) Glass spheres used in reflective paint (ballotini). E) Two oil mists diatacterized by direct injection into the Aerosizer .

Applications of microparticles can be found in medicine, biochemistry, colloid chemistry, and aerosol research [48]. Some uses include separation media for chromatographic application, high surface area substrates for immobilized enzymes, standards for calibration, spacers in optical cavities and liquid crystal displays, and three-dimensional microenvironments for cell encapsulation. It should be stressed that even a scaled-up MF synthesis enables generation of a relatively small amount of particles, in comparison with conventional emulsion, dispersions, or suspension polymerizations. Thus, most practical applications of such microbeads should utilize their high-value unique properties, for example, a uniform distribution of sizes and control of morphology, structure, and shape. Therefore, some of the demonstrated applications of polymer microbeads are still in the proof-of-concept stage. 

---