Selecting Quantitative Filter Paper on Amazon.com
Quantitative filter paper is a type of laboratory filter made from cotton cellulose fibers and is typically used to clarify solutions or recover particulate for a broad range of laboratory and industrial filtration applications, including gravimetric analysis, particulate identification, and sample preparation. A quantitative filter is typically placed inside a filter funnel, Hirsch, or Büchner funnel to trap particles from liquid or gas within the fibers of the filter paper.
Filter paper is available in a range of grades that represent increasing levels of cellulose purity, surface hardness, and chemical resistance. Quantitative filter paper has minimal ash content for increased purity, and filters are labeled as either "ashless" or "low ash" with an ash content ranging from 0.006% to 0.015%. Some filters are acid-hardened, for wet strength and chemical resistance. Available in square or rectangular sheets or as discs, quantitative filter paper can be flat or pre-pleated. Circular filters are designed in a variety of standard sizes, and range in diameter from 12mm to 450mm. Other factors to consider when choosing quantitative filter paper include the flow rate, loading capacity, retention value, thickness, and strength.
A quantitative filter can be designed to allow a slow, medium, or fast flow rate during filtration. To increase the flow rate and loading capacity, pre-pleated filter paper has a greater surface area to trap particles while maintaining filtration speed. Retention values can range between 2 and 25μm, and represent the maximum size of particles in liquid that can be trapped in that filter. Thickness can range from 115 to 220μm; thicker paper provides greater mechanical strength than thinner paper.
Quantitative filter paper is commonly used in gravimetric laboratory applications because it has low ash content. Hardened quantitative filter paper is suitable for use with acidic or alkaline suspensions. Manufacturers include Whatman.