Whatman No. 42 Quantitative Ashless Circles 55mm

Whatman No. 42 is the standard slow-flow quantitative ashless filter paper for fine precipitate collection, with 2.5µm retention and less than 0.007% ash content. Used in gravimetric methods requiring ignition of the filter - including determination of barium sulphate, calcium oxalate, and silica - across environmental, mineral analysis, food chemistry, and pharmaceutical quality-control workflows. Complies with standard gravimetric methods cited in ASTM, ISO, and equivalent procedures.