Whatman® Quantitative Filter Papers

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For Consistent Accuracy in Analytical Applications

These filter grades combine the characteristics of low ash content with progressively increasing wet strength for a filter paper of consistent high quality. Hardened low ash grade is <\n>suitable for recovery of precipitate from the filter surface, as in Buchner filtrations, an intermediate between ashless and qualitative grades. Hardened ashless grade has high wet strength and chemical resistance. Ashless grades ensure low levels of ash for routine quantitative gravimetric techniques.
Specifications: For medium speed and retention, Grade 40 (8µm) filters are typically used for analysis of components in clays, cements, iron and steel products, or as a primary filter for separating solids from aqueous extracts in soil analysis, or to determine quantitative sediments in milk. Fastest ashless filter paper Grade 41 (20-25µm) is recommended for analysis of coarse particles or gelatinous precipitates (iron or aluminum hydroxides). Also useful as a rapid filter for routine cleanup of biological fluids or organic extracts during analysis. Use Grade 50 (2.7µm)filters (thinnest of Whatman papers) for qualitative or quantitative filtrations that require vacuum assistance on Buchner or 3-piece filter funnels. Slow flow rate. Use Grade 541 (20-25µm) filters for fast filtration of coarse particles and gelatinous precipitates in acid/alkali solutions during gravimetric analysis (fiber in animal foodstuffs, gelatin in milk and cream, chloride in cement, and chloride and phosphorous in coal and coke). Boxes of 100.