Whatman Grade 4 Qualitative Filter Papers (20-25 µm particle retention) are a standard grade, high flow rate filter paper. They are useful in qualitative analytical separations when fast flow is required and the collection of fine particles is not critical.
These cellulose filters are used in qualitative analytical techniques to determine and identify materials (e.g., in air pollution monitoring).
They are also available as pre-pleated filters, which give improved flow rate and increased loading capacity compared to equivalent flat filters.
- Extremely high flow rate
- Excellent retention: captures coarse particles and gelatinous precipitates such as ferric hydroxide and aluminum hydroxideFast filtration: useful for routine clean-up of biological fluids or organic extracts during analysis