Whatman 1442-240 Filter Circles, 240mm Dia, Ashless Grade 42, 100/pk (PN:1442-240)

Whatman Grade 42 ashless filter circles are engineered for critical quantitative analysis, especially in gravimetric methods and sample preparation for instrumental analysis where accurate recovery of precipitates is required. Examples include calcium carbonate and barium sulfate filtration in environmental, cement, and materials testing workflows.

“Ashless” filter paper has very low residual ash content (≤ 0.007 %) after burning — meaning almost no inorganic residues remain after combustion. This is essential for gravimetric analysis because it ensures that the filter itself does not contribute to the final weight, improving accuracy in analytical results.

Grade 42 quantitative filter paper has a fine nominal particle retention of ~2.5 µm, allowing it to retain very fine precipitates while still providing a reasonable filtration speed — ideal for precise analytical separations.

This specific product features 240 mm diameter filter circles, a larger size suited for high-volume filtrations or large funnel setups, and is supplied as a pack of 100 discs, making it convenient for routine lab use.

Ashless Grade 42 is preferred when precise quantitative results are required, such as trace element analysis, soil particle separation, environmental filtrations, and any procedure where combustion or ashing occurs. The low ash and high purity reduce contamination and unwanted weight biases.