Generation using aerosol

The commonest form of sample introduction is by means of an aerosol generated using a pneumatic nebulizer. Several types of nebulizer can be used. All-glass concentric nebulizers (Fig. 4.7a) operate in a similar manner to those used for FAAS. Cross-flow nebulizers (Fig. 4.7b) operate by directing a high-velocity stream of gas across the mouth of a capillary... 

Experimental evaluation of various widely used commercial instruments has been undertaken by several investigators, including Liu et al. (1974), who used the vibrating orifice technique to generate spherical aerosols with narrow size distributions. Similarly, Pinnick and Auvermann (1979) generated droplets of a solution which were dried to make solid particles for evaluating the response of... 

Thermal decomposition—Thermal decomposition methods may be used to prepare metal oxide fumes. An aerosol of a precursor to the metal oxide (i.e., a substance that is readily decomposed, thermally, to yield the oxide) is first generated and then is heated by passing it through a heated tube to decompose it to the oxide. Metal formates, oxalates, and the like, which readily yield the oxides and do not produce objectionable side products, are commonly used precursors. In this program, fumes of iron oxide, vanadium oxide, and copper oxide were generated using this method. 

Lead, tellurium, and selenium aerosols in 0.01 to 1 micrometer size range could be generated using a condensation aerosol technique. The particle size is dependent on the generation temperature. The aerosol output is dependent on both the generation temperature and the carrier gas flow rate. 

This nozzle has been used to generate polydispersed aerosols of various organic liquids as the bulk phase. Particles in the size range of submicrometers to 20 pm were obtained. The concentration varied by less than 10% over several hours as long as the air pressure was well regulated. 

The technologies used to generate pharmaceutical aerosols are described in Section 10.5. 

Chlorine and bromine atoms were generated using UV and visible photolysis of molecular chlorine and bromine, respectively, in addition to UV (300 < k < 400 nm) photolysis of chloroacetyl chloride and dibromomethane. The reaction products were analyzed in the gas-phase, in suspended aerosols and on the wall of the reactor using MS, GC-MS and inductively coupled plasma mass spectrometry (ICP-MS). The major products identified were HgCb and HgBr2 adsorbed on the wall. Suspended aerosols, collected on the micron filters, contributed to less than... 

The size distribution of aerosols generated using most commercial nebulizers is typically highly variable with somewhat large mean diameters. This not only... 

Fleming, J.S. Nassim, M.A. Hashish, A.H. Bailey, A.G. Conway, J. Holgate, S. Halson, P. Moore, E. Martonen, T.B. Description of pulmonary deposition of radiolabeled aerosol by airway generation using a conceptional three dimensional model of lung morphology. J. Aerosol Med. 1995, 8 (4), 341-356. 

Aerosol Generation Liquid aerosols may be difficult to generate if they are extremely volatile, one may actually end up generating a vapor. Second, denser or more viscous liquids require greater energy to overcome surface tension and form droplets of the desired size. There are four widely used aerosol generation systems ... 

The ICP-OES nebulizers can aspirate up to 1-2% dissolved solids (a dry wine has 2-4% total extract). Some nebulizers, such as the Babington and cone-spray nebulizers, were studied to handle as much as 15-20% dissolved solids, but are not ideally conceived for use in ICP-MS. Pneumatic nebulizers are commonly used to generate an aerosol of samples with dissolved components below 0.2%. Pneumatic devices are made from glass or different kinds of polymers and use argon as nebulizer gas. The characteristics of some of the most popular pneumatic nebulizers are detailed below. 

Jet and ultrasonic nebulizers have been used to aerosolize antimicrobial therapy. Jet nebulizers used compressed air or oxygen passed through a liquid to produce an aerosol gas. With ultrasonic devices, a piezoelectric element vibrates to generate small aerosol particles. Both systems have advantages and limitations related to their components and technique of use. These are discussed in more detail elsewhere in this text (see Chs. 8, 12). 

The merits of liposome antibiotic therapy vs. antibiotic alone seem rarely to have been compared directly. Studies have shown benefit of using some liposome antifungals [92], but the formulations were either under development or were commercialized as a liposome product for administration by injection [93]. So the debate must continue. Although liposomal formulations can be generated and aerosolized and have proved effective in combination with various drugs, do the benefits ultimately outweigh the issues developing these kinds of formulations [94] ... 

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