Aerosol principles

Mercer, T.T. (1981). Production of therapeutic aerosols principles and techniques. Chest 80 (Suppl. 6) 813-818. 

The metered solution inhaler (MSI), under development by Sheffield Pharmaceuticals, uses the same aerosolization principle as the AeroDose. The MSI is a portable, hand-held drug delivery device, as shown in Fig. 13. Using a motorized pump, drug solution is delivered to the surface of a ultrasonic horn powered... 

To examine a sample by inductively coupled plasma mass spectrometry (ICP/MS) or inductively coupled plasma atomic-emission spectroscopy (ICP/AES), it must be transported into the flame of a plasma torch. Once in the flame, sample molecules are literally ripped apart to form ions of their constituent elements. These fragmentation and ionization processes are described in Chapters 6 and 14. To introduce samples into the center of the plasma flame, they must be transported there as gases or finely dispersed droplets of a solution or as fine particulate matter (aerosol). The various methods of sample introduction are described here in three parts — A, B, and C Chapters 15, 16, and 17 — to cover gases, solutions (liquids), and solids. Some types of sample inlets are multipurpose and can be used with gases and liquids or with liquids and solids, but others have been designed specifically for only one kind of analysis. However, the principles governing the operation of inlet systems fall into a small number of categories. This chapter deals specifically with substances that are normally solids at ambient temperatures. 

Nebulizers are used to introduce analyte solutions as an aerosol spray into a mass spectrometer. For use with plasma torches, it is necessary to produce a fine spray and to remove as much solvent as possible before the aerosol reaches the flame of the torch. Various designs of nebulizer are available, but most work on the principle of interacting gas and liquid streams or the use of ultrasonic devices to cause droplet formation. For nebulization applications in thermospray, APCI, and electrospray, see Chapters 8 and 11. 

Aerosol-Based Direct Fluorination. A technology that works on Hter and half-Hter quantities has been introduced (40—42). This new aerosol technique, which functions on principles similar to LaMar direct fluorination (Fig. 5), uses fine aerosol particle surfaces rather than copper filings to maintain a high surface area for direct fluorination. The aerosol direct fluorination technique has been shown to be effective for the synthesis of bicycHc perfluorocarbon such as perfluoroadamantane, perfluoroketones, perfluoroethers, and highly branched perfluorocarbons. 

Willeke, K., and Baron, P. A., "Aerosol Measurement—Principles, Techniques, and Applications." Van Nostrand Reinhold, New York, 1993... 

Several separating systems are used for particulate sampling. All rely on some principle of separating the aerosol from the gas stream. Many of the actual systems use more than one type of particulate collection device in series. If a size analysis is to be made on the collected material, it must be remembered that multiple collection devices in series will collect different size fractions. Therefore, size analyses must be made at each device and mathematically combined to obtain the size of the actual particulate in the effluent stream. In any system the probe itself removes some particulate before the carrying gas reaches the first separating device, so the probe must be cleaned and the weight of material added to that collected in the remainder of the train. 

Air contaminants in solid or liquid state (aerosols), e.g., wood dust, welding smoke, or oil mist, are all in principle directly visible. The dispersion of those contaminants and the airflow patterns around the source may therefore be studied without any special tools. It is, however, not always possible to see the contaminant if, for example, the concentration in the air is low, the size of the particles is small, or the lighting is poor. The fact that the contaminant can t be seen may stem from the acceptable low level of the concentration but that can of course not be used to conclude that the control is acceptable. That conclusion depends not only on the contaminant s toxicological qualities but on how visible it is iit air. The ability to see the particles directly is also, as said above, a function of their size. Small particles, able to be transported deep into the thinner airways of the lungs, are many times also difficult to see directly. 

Two other principles that have been made commercially available are (11 rhe reaction between pyrosulfuric acid (H2S2O7) and water (water vapor in air) to form sulfuric acid aerosol and (2) rhe reaction between ritaiJium tetrachloride (TiCl4) and water to form titanium dioxide (TiO,) and hydrogen chloride il Id), higure 12.5 shows two different hand-held, disposable smoke emitters. 

Field protection The principles applied to the nerve agents apply equally as well to the incapacitating agents. It is possible that such agents will be disseminated by smoke-producing munitions or aerosols, using the respiratory tract as a route of entry. The use of protective mask, therefore, is essential. The skin is usually a much less effective route. 

The principle of inertial impaction is employed to sample aerosols aerodynamically for characterization of particle size and will be dealt with theoretically later in this chapter. 

Particulate diffusion does not play a significant role in the deposition of pharmaceutical aerosols. However, it is worth noting the mechanism by which diffusion of particles occurs in the lungs. The principle of Brownian motion is responsible for particle deposition under the influence of impaction with gas molecules in the airways. The amplitude of particle displacement is given by the following equation ... 

The basic principle for 210Pb dating is that gaseous 222Rn is emitted to the atmosphere from the lithosphere, surface waters and airborne dust and there decays to 210Pb. After formation in the troposphere, 2l0Pb becomes attached to aerosol particles which reside in the atmosphere for only 30 days or less depending on season, latitude, frequency of rainfall, size and altitude of the aerosols, Nevissi et al., [17]1, Schell [26], and Poet et al., [19]. — —... 

A colloid is a broad category of mixtures, and is defined as one phase suspended in another. A perfume spray is made up of a liquid (the perfume) dispersed in a gas (the air). The principle underlying the perfume atomizer is the same as the nozzle on a can of polish, and the jets within the carburettor in the internal combustion engine. In each case, the colloid formed is an aerosol. 

Upper respiratory tract irritation can occur from inhalation of a medicinal gas, vapor, or aerosol. For assessing the potential of an inhalant to cause URT irritation, the mouse body plethysmographic technique (Alarie, 1966, 1981a, b) has proven to be extremely usefid. This technique operates on the principle that respiratory irritants stimulate the sensory nerve endings located at the surface of the respiratory tract from the nose to the alveolar region. The nerve endings in turn stimulate a variety of reflex responses (Alarie, 1973 Widdicombe, 1974) that result in characteristic changes in inspiratory and expiratory patterns and, most prominently, depression of respiratory rate. Both the potency of irritation and the concentration of... 

It is the purpose of this chapter to summarize knowledge dealing with the role of electrostatic phenomena in particulate systems, especially in aerosols. A relatively comprehensive annotated bibliography by Blake and Lapple (BIO) has surveyed the bulk of the literature through 1965. This chapter cites and summarizes the results of the more important or directly relevant work in this field.1 However, before considering specific phenomena, it is desirable to review some of the fundamental principles in the field of electrostatics. 

A further proof of principle was conducted by Cooney et al. who demonstrated the feasibility of the Andersen cascade impactor as a cell compatible deposition device [90], Permeability coefficients of fluorescent isothiocyanate-labeled dextrans after impaction as aerosols on Calu-3 cells were calculated. Deposition did not negatively affect the cell monolayer integrity. 

Assuming that some of the physical and chemical mechanisms just reviewed are predominant in the formation of organic aerosol, various schemes can be derived that permit a more quantitative description of the time evolution of atmospheric organic aerosol. For example, a kinetic scheme has been proposed recently (Grosjean and Friedlander, unpublished data) for aerosol formation from ole ic precursors that may be applied in principle to other hydrocarbon classes. Starting with this system. 

The analytic principles that have been applied to accumulate air quality data are colorimetry, amperometry, chemiluminescence, and ultraviolet absorption. Calorimetric and amperometric continuous analyzers that use wet chemical techniques (reagent solutions) have been in use as ambient-air monitors for many years. Chemiluminescent analyzers, which measure the amount of chemiluminescence produced when ozone reacts with a gas or solid, were developed to provide a specific and sensitive analysis for ozone and have also been field-tested. Ultraviolet-absorption analyzers are based on a physical detection principle, the absorption of ultraviolet radiation by a substance. They do not use chemical reagents, gases, or solids in their operation and have only recently been field-tested. Ultraviolet-absorption analyzers are ideal as transfer standards, but, as discussed earlier, they have limitations as air monitors, because aerosols, mercury vapor, and some hydrocarbons could, interfere with the accuracy of ozone measurements made in polluted air. 

Newman SP, Pavia D, In Aerosols in Medicine Principles, Diagnosis and Therapy (Eds Moren F, Newhouse MT, Dolovich MB), pp. 193-218. Elsevier Scientific Publishers, Biomedical Division, London, 1985. 

---