Term: filter
https://doi.org/10.1351/goldbook.F02384

Definition:
A porous material on which solid particles present in air or other fluid which flows through it are largely caught and retained. Filters are made with a variety of materials: cellulose and derivatives, glass fibre, ceramic, synthetic plastics and fibres. Filters may be naturally porous or be made so by mechanical or other means. membrane/ceramic filters are prepared with highly controlled pore size in a sheet of suitable material such as polyfluoroethylene, polycarbonate or cellulose esters. Nylon mesh is sometimes used for reinforcement. The pores constitute 80–85% of the filter volume commonly and several pore sizes are available for air sampling (0.45-0.8 µm are commonly employed).

Related Terms:
1) ceramic (http://doi.org/10.1351/goldbook.CT07540).
2) membrane (http://doi.org/10.1351/goldbook.MT06878).
3) esters (http://doi.org/10.1351/goldbook.E02219).

Source: PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2188 (https://doi.org/10.1351/pac199062112167)

Citation: 'filter' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.F02384

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