Grade 589/3 Quantitative Filter Paper Ashless (Ash 0.01%), circles. These are very pure filters suitable for a wide range of critical analytical filtration procedures. Whatman quantitative filters from GE Healthcare are designed for gravimetric analysis and the preparation of samples for instrumental analysis. They are available in three formats designed to meet specific needs. "Blue Ribbon Filter": Ashless standard filter paper for very fine precipitates (class 2d acc. to DIN 53 135). Slow filter paper with highest efficiency for collecting very small particles. Also used for many routine analytical methods in different industries (e.g., determination of the amount of insoluble contaminants in animal and vegetable fats and oils). Also available prepleated as Grade 589/3 ½. Grade 589/3: 2 µm