This Whatman 15.0cm, grade 4, cellulose filter paper is used in qualitative analytical techniques to determine and identify materials. It is extremely fast filtering. It provides excellent retention of coarse particles (20-25µm) and gelatinous precipitates such as ferric hydroxide and aluminium hydroxide. It is very useful as a rapid filter for routine cleanup of biological fluids or organic extracts during analysis. This filter paper is used when high flow rates in air pollution monitoring are required and the collection of fine particles is not critical. Retention: 20-25µm. Dimensions: 15.0cm. 100/Pack. Whatman #: 1004-150.