CYTIVA WHATMAN

Qualitative filter papers are used for general filtration and clarification, where the ash content is not critical. They are available in grades with different porosities, such as Grade 1, 2, 3, 4, 5, and 6, and are typically used for routine separations. Quantitative filter papers, such as Grade 40, 42, and 54, are designed for gravimetric analysis and have low ash content to minimize interference with weighing. They are often acid-hardened or ashless, and their ash content is specified to ensure accurate results. Quantitative papers are also available in different porosities and diameters to match specific retention requirements.

Cytiva Whatman cellulose nitrate membrane filters are available in pore sizes ranging from 0.2 µm to 5 µm. Common pore sizes include 0.2 µm, 0.45 µm, 0.8 µm, 1.2 µm, and 5 µm. These filters are used for particle retention, sterilization, and sample preparation. The choice of pore size depends on the application; for example, 0.2 µm is used for sterile filtration, while 5 µm is suitable for retaining larger particles. Membrane filters come in various diameters, such as 47 mm, and can be sterile or non-sterile.

Hardened low ash filter papers are treated to increase their wet strength and reduce ash content. The hardening process involves exposing the paper to a chemical treatment that makes it more resistant to disintegration when wet, allowing it to be used in vacuum filtration and with strong acids or alkalis. Low ash content means that the paper leaves minimal residue after burning, which is critical for gravimetric analysis where the weight of the precipitate is measured. Cytiva Whatman Grade 54 is an example of a hardened low ash filter paper with a minimum pore size of 20 µm and a thickness of 0.185 mm.

Yes, Cytiva Whatman filter papers are used in various industrial applications, including environmental testing, food and beverage analysis, and quality control. For example, qualitative filter papers are used for clarifying liquids and separating particles in process streams. Quantitative filter papers are used in gravimetric analysis for determining solid content in industrial samples. The papers are available in large diameters, such as 32 cm, to accommodate different filtration setups. Their consistent performance and range of porosities make them suitable for both laboratory and industrial filtration tasks.

Cytiva Whatman filter papers do not have a specific shelf life when stored properly. They should be kept in a dry, clean environment away from direct sunlight and contaminants. The packaging is designed to protect the papers from moisture and dust. As long as the papers remain dry and free from physical damage, they can be used over an extended period. However, it is good practice to check for any signs of deterioration, such as discoloration or brittleness, before use. For critical applications, always refer to the manufacturer's recommendations.

Selection depends on the retention required, flow rate, and whether the filtrate or the residue is of interest. For general filtration with medium retention and fast flow, Grade 1 or Grade 2 qualitative papers are common. For finer retention, Grade 5 is used. For gravimetric analysis, quantitative grades like 40, 42, or 54 are appropriate, with 54 offering coarse porosity and high wet strength. Consider the diameter to fit your filtration apparatus, and the thickness for mechanical strength. If you need low ash content, choose quantitative grades. For sterile filtration, use membrane filters with the appropriate pore size.