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:

• Acid-treated for high wet-strength
• Extremely low ash content (0.006% ash maximum)
• Nominal particle retention of 8 µm
• Medium flow rate (Herzberg filtration speed 200 s)
• High chemical resistance to strong acid and alkali suspensions

Hardened low ash grades: 0.015% ash maximum – treated with a strong acid to remove trace metals. The maximum ash content of these grades is intermediate between ashless and qualitative. They are particularly suitable for Büchner filtrations where it is desirable to recover the precipitate from the filter surface after filtration. Other characteristics include high wet strength and chemical resistance which are similar to the acid hardened ashless filter papers.

Hardened ashless grades: Quantitative filter papers with 0.006% ash maximum featuring high wet strength and chemical resistance. These papers are acid hardened, which reduces ash to an extremely low level. Their tough surfaces make them suitable for a wide range of critical analytical filtration operations. Each grade offers a convenient combination of filtration speed and particle retention.