Aqueous Filter Extractables: Detection and Elution from Process Filters

Abstract

Many filters release particles and water-soluble materials when eluted with distilled water. Some filters tend to shed a proportion of the filter matrix (media migration ); membrane filters not previously rinsed sometimes shed a small amount of matrix, often cutting debris. Most membrane filters contain a nonionic detergent as a wetting agent, a plaslicizer such as glycerol, and a small amount of inorganic electrolyte (often calcium salts). The water-soluble organic solutes can be detected by reverse-phase thin layer chromatography and by isocratic reverse-phase high performance liquid chromatography. Solutes isolated by these two procedures are partially identified by UV or IR absorbance. Inorganic solutes are quantitated by atomic absorbance spectroscopy. With the possible exception of fibers released from depth filters, the extractables are harmless to mice and guinea pigs, but can interfere with analyses.