Whatman quantitative filters are designed for gravimetric analysis and the preparation of samples for instrumental analysis. They are available in three formats designed to meet your specific needs.
Ashless: 0.007% ash maximum for Grades 40 to 44 and a maximum of 0.01% for the 589 Grades-very pure filters suitable for a wide range of critical analytical filtration procedures.
Hardened low ash: 0.015% ash maximum-treated with a strong acid to remove trace metals and produce high wet strength and chemical resistance. These filters are particularly suitable for Büchner filtration where the tough smooth surface of the filter makes it easy to recover precipitates.
Hardened ashless: 0.006% ash maximum-acid hardened to give high wet strength and chemical resistance with extremely low ash content. The tough surface makes these filters suitable for a wide range of critical filtration procedures.
Grade 589/1 ½ : 12-25 μm (fast filter paper)
Prepleated ′Black Ribbon Filter′, the established standard in quantitative analysis for the filtration of coarse precipitates (class 2a acc. to DIN 53 135). Ashless filter paper with very high flow rate. Used for many quantitative standard methods, especially for gravimetric applications (e.g., determination of the ash content in foodstuffs), or for the Blaine test in the cement industry.