Whatman 1442-125 Filter Circles, 125mm Dia, Ashless Grade 42, 100/pk (PN:1442-125)

Whatman Ashless Grade 42 filter circles are high-purity, quantitative filter papers designed for precision gravimetric analysis and analytical filtration, where accurate collection and weighing of precipitates are required. They’re commonly used in environmental, industrial, and research labs for sample preparation and analysis.

“Ashless” means the filter paper leaves very little residue (≤ 0.007%) after combustion, which is critical in gravimetric analysis because any leftover ash could affect the measured weight of your sample. This makes Grade 42 ideal for applications where accuracy in weight after ashing is essential.

Grade 42 filter paper has a nominal particle retention of ~2.5 µm, meaning it efficiently captures fine particulates while allowing liquid to pass through more slowly and consistently — a key trait for high-precision filtration tasks.

This product includes 100 filter circles, each with a 125 mm diameter — a size commonly used with larger funnels and filtration setups in lab workflows requiring substantial filtration surface area.

Grade 42 is ideal for critical analytical tasks such as filtering fine precipitates (like calcium carbonate or barium sulfate) in environmental analysis, soil testing, cement analysis, and sample prep for instrumental analysis. Its high purity and fine retention make it suitable anytime low background contamination is crucial.