| Abstract: | Characteristics are presented of various new filter materials of polyvinyl chloride--polyacrylonitrile, polyimide, polyaromatic, and of quartz fibers. These filters have been specifically developed for air sampling applications. Included in the presentation are comparative performance characteristics such as: infrared and ultraviolet spectra, inorganic and trace metals analyses, chemical compatibilities and reactivities with various liquids and gases, moisture pick-up, mass per unit area, mechanical properties (tensile strength and elongations), air flows/pressure drops, and particle retention efficiencies. Examples are presented of the increased acceptance of membrane filters in air analyses due to their simplifying tedious conventional procedures and their improvement of sensitivity, precision, and accuracies. Included are the ability of specific synthetic filters to impart optical transparency for analyses of asbestos and other fibers by transmission techniques using oil immersion or dispersion staining, the direct determination of silica on an acrylonitrile membrane by infrared, the direct determination of atmospheric particulate types and the concentrations of each. Other examples given are trace metal analyses by X-ray fluorescence, and gravimetric procedures and scanning electron microscopy techniques for analyses of suspended particulate matter. |
