Visibility, particulates

Instruments that measure scattered light, such as the Photo-Nephelometer (Coleman Instruments, Oak Brook, IL), are used to evaluate and set clarity standards for parenteral preparations. It is not possible to establish an overall standard value for all products (e.g., 30 ne-phelos) because the value itself is relative and influenced by many factors, including concentration, aging, stopper extracts, and the solubility characteristics of the raw materials. Nephelometer readings are insensitive to contamination by large (visible) particulates. 

Reconstitution. Times required for reconstitution and the appearance of the constituted solution are also of importance. The nature of the dried material as a result of lyophilization often yields a product that is highly hygroscopic. Reconstitution is often instantaneous on addition of the diluent. For ease of use in a clinical setting, reconstitution times are often less than 2 min. Whatever time is required to resolubilize that material, the constituted solution should be clear and free of any visible particulates or insoluble materials, meeting the compendial requirements such as those outlined within the USP [31]. 

Particulate matter is viewed as unacceptable contamination in parenteral solutions. It is recognized that subvisible particulate matter will exist in certain amounts, but the USP now has limits for acceptable levels of particulate matter for SVIs (no more than 6000 particles per container >0.5 pm no more than 600 particles per container >25 pm). The USP is the only compendium in the world that contains limits for subvisible particulates in SVIs. All worldwide compendia have subvisible particle limits (particles per milliliter) for large-volume injections. SVI solutions with visible particulate matter should not used. Particulate matter creates problems in product quality and clinical safety. The primary sources of particulate matter are the container-closure systems and personnel. 

Decreased particulate matter, which reduces the number of units rejected for visible particulate matter... 

Particulate matter testing. Particulate matter testing will normally include limits for visible particulates and/or clarity of solution, as well as for subvisible particles. 

Visual appearance of the product (color and opacity for solutions and suspensions color, texture, and dissolution time for powders), visible particulates in solutions or after the reconstitution of... 

If the nodularisation off-gas is not captured, this could result in the melting shop filling-up with a white smoke, and MgO dust drop out. Exhausting without filtration can result in a visible emission from the foundry. A large volume of visible particulate can be generated in a relatively short period of time, but usually only lasts for a short duration (5 to 10 minutes for each batch treated). 

Membrane and filtration processes have historically been utilized for the treatment and purification of drinking water. For this application, filtration is used to remove a wide variety of constituents, ranging from visible particulates (sand filters, refer to Chapter 5) to ionic species (reverse osmosis, refer to Chapter 4). From these conventional applications, new uses of membrane separations have recently been applied to the treatment of hazardous waste streams. 

A third type of regional problem is that of visibility. Visibility may be reduced by specific plumes or by the regional levels of particulate matter that produce various intensities of haze. The fine sulfate and nitrate particulates just discussed are largely responsible for reduction of visibility (see Chapter 10). This problem is of concern in locations of natural beauty, where it is desirable to keep scenic vistas as free of obstructions to the view as possible. 

Airborne particulates include dust, fume and aerosols. Many such particles are invisible to the naked eye under normal lighting but are rendered visible, by reflection, when illuminated with a strong beam of light. This is the Tyndall effect and use of a dust lamp provides a simple technique for the rapid assessment of whether a dust is present, its flow pattern, leak sources, the effects of ventilation, etc. More sophisticated approaches are needed for quantitative data. Whether personal, spot or static sampling is adopted will depend upon the nature of the information required. 

Atmospheric chemistry influences human health, climate, food production, and through its impact on visibility, our view of the world. Chemicals in the air affect us with each breath we take. Suspended particulate matter that form from gas-phase reactions affect the amount of solar energy reaching the earth s surface. 

Particulate emissions have their greatest impact on terrestrial ecosystems in the vicinity of emissions sources. Ecological alterations may be the result of particulate emissions that include toxic elements. Furthermore, the presence of fine particulates may cause light scattering, known as atmospheric haze, reducing visibility and adversely affecting transport safety, property values, and aesthetics. 

Particulate material consists of solid or liquid substances that may be visible or invisible. The particles affect visibility and can be transported over long distances by wind. The small particles, less than PM, are particularly dangerous to human health as they can pass through nostril hairs (cilia) and enter the lungs. 

Haze The presence of particulate matter in the air, reducing visibility. 

Plume Effluent discharged from a chimney or exhaust duct, composed of gases alone or gases and particulate matter. The plume shape depends on temperature difference and turbulence. The flow of visible hot gases or vapor from an outlet. 

Acid deposition and the associated particulate nitrates and sulfates are implicated in the deterioration of certain sensitive ecosystems, decreased visibility, negative human health effects, and increased degradation of certain stone building materials and cultural resources, especially those made of limestone and marble. Fine particulate nitrate and sulfate particles... 

White P, either in bulk or in soln, is a good example of the burning type of smoke generator. The resulting colloidal suspension of P pentoxide is quickly hydrolyzed by moisture to become phosphoric acid droplets which are the actual visible constituent of the smoke. Various other burning type smoke generators exist such as those used for signaling purposes and which use red P, metallic phosphides, or P trichloride as the source of the particulate cloud... 

Particulates Chemical processes Fuel combustion Construction Incineration processes Motor vehicles Nuisance Adverse health effects Reduced visibility Deposition on buildings... 

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