Application of Molecular Filter Membranes to the Analysis of Aerosols

Journal/Book: Reprinted from AMERICAN JOURNAL OF PUBLIC HEALTH Vol. 43 No. 2 February 1953 Copyright by the American Public Health Association Inc. 1790 Broadway New York N. Y.. 1953;

Abstract: ALEXANDER GOETZ PH.D. Professor California Institute of Technology Pasadena Calif. * Presented before the Engineering Section of the American Public Health Association at the Eightieth Annual Meeting in Cleveland Ohio October 23 1952. Membrane fitters have been experimented with for many years but only very recently have they been perfected to permit their use in filtering air. Though this is a highly technical paper others than laboratory workers will also find it useful especially the last part dealing with microbiologic aerosols. THE use of molecular filter membranes (MF) in the field of public health has caused considerable interest during the last 18 months because of their application to bacteriological water tests where certain MF types specifically developed for this use promise to supplement or even in part replace present standard methods. Fairly well developed procedures for this purpose have been developed already.1-7 The utility of MF's is however not restricted to the analysis of liquids-in fact it appears from extended studies in the laboratory and the field that certain MF types originally developed by the author and his collaborators2 promise an even more diversified utility in the analysis of aerosols. The following discussion presents the first brief survey of the nature and the application of MF membranes to the assay of atmospheric environment for suspended particulate matter. The principal requirement for aerosol assays is the quantitative separation and the rapid concentration of suspended matter regardless of particle size in such a manner that the retained "concentrate" is subsequently available for analysis and study. It appears that the physical properties of MF material are uniquely capable of fulfilling these conditions. Their brief discussion thus appears indicated. THE PROPERTIES OF MOLECULAR FILTER MEMBRANES In contradistinction to air-screening devices such as fabrics wire screens etc. where the size of the retained particles is determined by the size of the more or less uniform interstices or to statistical conglomerates of fibers with undefined pore apertures (paper asbestos etc. filters) the molecular filter membranes represent dry gels of micellic structure the elements of which are of molecular order of magnitude and are held permanently without the use of binding agents by intermolecular forces. ... ___MH

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